bridge inspection manual version 19

Bridge Inspection Field ManualVersion 1.9 - November, 2011

Minnesota Department of Transportation

MnDOT Bridge Office - Bridge Inspection Contacts

Title/Unit Name Phone EmailState Bridge Engineer Nancy Daubenberger (651) 366-4501 [email protected]

Bridge Construction &Maintenance Engineer(Insp. Program Manager)

Tom Styrbicki (651) 366-4507 [email protected]

Bridge StructuralEvaluation Engineer

Jihshya Lin (651) 366-4490 [email protected]

Bridge Inspection &Fabrication Engineer

Todd Niemann (651) 366-4567 [email protected]

Bridge Inspection(Fracture Critical Bridge

Inspection, Non-DestructiveTesting, NBIS Reviews, and

Inspector Certification)Fax: (651) 366-4566

Jennifer Zink (651) 366-4573 [email protected] Fishbein (651) 366-4537 [email protected]

David Hedeen (651) 366-4528 [email protected] Wilson (651) 366-4574 [email protected] Nelson (651) 366-4575 [email protected] Rand (651) 366-4576 [email protected]

Scott Theisen (651) 366-4475 [email protected] Potter (651) 366-4471 [email protected]

Bridge Management(Bridge data entry & reports)

Thomas Martin (651) 366-4555 [email protected] Hartfiel (651) 366-4557 [email protected]

Bridge Load Ratings(Load Ratings and Load

Postings)

Yihong Gao (651) 366-4492 [email protected] Pierce (651) 366-4555 [email protected]

Moises Dimaculangan (651) 366-4522 [email protected]

Bridge Hydraulics(Scour Analysis & Scour

Action Plans)

Petra DeWall (651) 366-4473 [email protected]

Andrea Hendrickson (651) 366-4466 [email protected]

Nicole Danielson-Bartlett

(651) 366-4474nicole.danielson-

[email protected]

State Aid Bridge(Plan Review & Funding

Eligibility)

Dave Conkel (651) 366-4493 [email protected]

Steve Brown (651) 366-4495 [email protected]

State Aid(County/Local Underwater

Bridge Inspections)Paul Stine (651) 366-3830 [email protected]

Bridge Inspection Field Manual(Version 1.9 - November, 2011)

MnDOT Bridge Office3485 Hadley Avenue North

Oakdale, MN 55128-3307

mailto:[email protected]













































MnDOT BRIDGE INSPECTION MANUAL3

Table of Contents

SECTION 1: INTRODUCTION............................................................................................. 6

SECTION 2: NBI CONDITION RATINGS.......................................................................... 7

2.1 NBI BRIDGE CONDITION RATINGS .................................................................................. 72.1.1 NBI Deck Condition Rating (FHWA Item #58) .......................................................... 82.1.2 NBI Superstructure Condition Rating (FHWA Item #59)........................................... 92.1.3 NBI Substructure Condition Rating (FHWA Item #60) ............................................ 102.1.4 NBI Channel/Channel Protection Condition Rating (FHWA Item #61) .................. 112.1.5 NBI Culvert Condition Rating (FHWA Item #62)..................................................... 12

2.2 BRIDGE APPRAISAL RATINGS & OTHER ITEMS .............................................................. 132.2.1 Waterway Adequacy Appraisal Rating (FHWA Item #71) ....................................... 132.2.2 Approach Roadway Alignment Appraisal Rating (FHWA Item #72) ....................... 142.2.3 Bridge Deficiency Status........................................................................................... 152.2.4 Bridge Sufficiency Rating ......................................................................................... 152.2.5 MnDOT Scour Codes and Channel Cross-Sections ................................................. 162.2.6 Structure Open, Posted, or Closed to Traffic (FHWA Item #41).............................. 192.2.7 Bridge Signage (Required) ....................................................................................... 202.2.8 Roadway Area & Unsound Wearing Surface Percentage ........................................ 242.2.9 Painted Area & Unsound Paint Percentage............................................................. 24

SECTION 3: STRUCTURAL ELEMENT CONDITION RATINGS .............................. 25

3.1 INTRODUCTION TO STRUCTURAL ELEMENT CONDITION RATINGS ................................. 253.1.1 Background of Structural Element Condition Ratings ............................................. 253.1.2 Structural Element Types.......................................................................................... 253.1.3 Structural Element Quantities & Ratings ................................................................. 263.1.4 Structural Element Display (Bridge Inspection Reports) ......................................... 263.1.5 Structure Units .......................................................................................................... 26

3.2 MNDOT STRUCTURAL ELEMENT LIST .......................................................................... 273.3 DECK & SLAB STRUCTURAL ELEMENTS ........................................................................ 31

3.3.1 Rating Procedures for Concrete Decks & Slabs....................................................... 313.3.2 Concrete Decks & Slabs (Without Overlays)............................................................ 323.3.3 Concrete Decks & Slabs (Low Slump Overlays) ...................................................... 323.3.4 Concrete Decks & Slabs (Latex or Epoxy Overlays)................................................ 333.3.5 Concrete Decks & Slabs (Bituminous Overlays) ...................................................... 333.3.6 Timber Decks & Slabs .............................................................................................. 343.3.7 Other Deck Types...................................................................................................... 353.3.8 Deck Joints................................................................................................................ 373.3.9 Roadway Approach Elements ................................................................................... 413.3.10 Bridge Railing Elements ....................................................................................... 42

3.4 STRUCTURAL ELEMENTS (GROUPED BY MATERIAL TYPE) ............................................ 443.4.1 Painted Steel Elements.............................................................................................. 443.4.1a Painted Steel Beam Ends (Element #422) ........................................................... 453.4.2 Weathering Steel Elements ....................................................................................... 463.4.3 Reinforced Concrete Elements.................................................................................. 473.4.4 Prestressed/Post-Tensioned Concrete Elements....................................................... 483.4.5 Timber Elements ....................................................................................................... 493.4.6 Masonry, Other, or Combination Material Elements............................................... 50

3.5 OTHER STRUCTURAL ELEMENTS.................................................................................... 51


3.5.1 Bearings .................................................................................................................... 513.5.2 Pin & Hanger (or Fixed Pin) Assemblies ................................................................. 593.5.3 Hinge Bearing Assemblies ........................................................................................ 613.5.4 Steel Cables............................................................................................................... 653.5.5 Secondary Structural Elements................................................................................. 663.5.6 Cast-in-Place (CIP) Piling ....................................................................................... 673.5.7 Tunnels...................................................................................................................... 67

3.6 CULVERT STRUCTURAL ELEMENTS................................................................................ 683.6.1 Inspection Procedures for Culverts .......................................................................... 683.6.2 Condition Rating Guidelines for Culverts ................................................................ 703.6.3 Steel Culvert (Element #240) .................................................................................... 713.6.4 Concrete Culvert (Element #241) ............................................................................. 713.6.5 Timber Culvert (Element #242) ................................................................................ 723.6.6 Masonry, Other, or Combination Material Culvert (Element #243)........................ 723.6.7 Culvert End Treatment (Element #388).................................................................... 733.6.8 Culvert Footing (Element #421) ............................................................................... 73

3.7 SMART FLAG ELEMENTS ................................................................................................ 743.7.1 Fatigue Cracking Smart Flag (Element #356) ......................................................... 743.7.2 Pack Rust Smart Flag (Element #357)...................................................................... 753.7.3 Concrete Deck Cracking Smart Flag (Element #358).............................................. 753.7.4 Underside of Concrete Deck Smart Flag (Element #359) ........................................ 763.7.5 Substructure Settlement & Movement Smart Flag (Element #360).......................... 763.7.6 Scour Smart Flag (Element #361) ............................................................................ 773.7.7 Traffic Impact Smart Flag (Element #362)............................................................... 773.7.8 Section Loss Smart Flag (Element #363).................................................................. 783.7.9 Critical Finding Smart Flag (Element #964)............................................................ 783.7.10 Concrete Shear Cracking Smart Flag (Element #965)......................................... 793.7.11 Fracture Critical Smart Flag (Element #966) ...................................................... 793.7.12 Gusset Plate Distortion Smart Flag (Element #967)............................................ 80

3.8 OTHER BRIDGE ELEMENTS ............................................................................................ 813.8.1 Signing (Element #981)............................................................................................. 813.8.2 Approach Guardrail (Element #982)........................................................................ 813.8.3 Plowstraps (Element #983)....................................................................................... 813.8.4 Deck & Approach Drainage (Element #984) ........................................................... 823.8.5 Slopes & Slope Protection (Element #985) ............................................................... 823.8.6 Curb & Sidewalk (Element #986)............................................................................. 823.8.7 Roadway over Culvert (Element #987)..................................................................... 833.8.8 Miscellaneous Items (Element #988) ........................................................................ 83

APPENDIX A: BRIDGE COMPONENTS & STRUCTURE TYPES ............................. 84

A.1 SUBSTRUCTURE COMPONENTS....................................................................................... 84A.1.1 Condition Rating Procedures for Abutments........................................................ 84A.1.2 Condition Rating Procedures for Piers ................................................................ 88

A.2 SUPERSTRUCTURE COMPONENTS ................................................................................... 92A.2.1 Condition Rating Procedures for Truss Connection Elements............................. 92A.2.2 Measuring and Documenting Section Loss on Steel Members............................. 93

APPENDIX B: BRIDGE LOAD CAPACITY RATINGS................................................. 96

B.1 GENERAL LOAD RATING INFORMATION ........................................................................ 96


B.1.1 Load Ratings - Basic Requirements...................................................................... 96B.1.2 General Re-rating Guidelines............................................................................... 96

B.2 ROLE OF THE BRIDGE INSPECTOR (LOAD RATINGS)....................................................... 96B.2.1 Documenting the Condition of Primary Structural Elements............................... 97B.2.2 Identifying and Reporting Additional Dead Loads............................................... 97B.2.3 Verification of Load Posting Signage................................................................... 98B.2.4 Verification of Member Sizes and Steel Type ....................................................... 98

B.3 ROLE OF THE INSPECTION PROGRAM ADMINISTRATOR (LOAD RATINGS) ...................... 99B.3.1 MnDOT District Program Administrators............................................................ 99B.3.2 County/Local Program Administrators ................................................................ 99

B.4 LOAD RATING REVIEW - BRIDGE CONDITION RATINGS ............................................... 100B.4.1 Changes in NBI Condition Ratings..................................................................... 100B.4.2 Changes in Structural Element Condition Ratings............................................. 100

B.5 LOAD RATING REVIEW - STRUCTURE INVENTORY ITEMS ............................................ 101B.5.1 Load Rating Date................................................................................................ 101B.5.2 Wearing Surface Type, Depth and Year of Installation...................................... 101B.5.3 Posting ................................................................................................................ 101B.5.4 Operating Rating (FHWA Item #64)................................................................... 102B.5.5 Inventory Rating (FHWA Item #66).................................................................... 102B.5.6 Design Load (FHWA Item #31) .......................................................................... 102B.5.7 MnDOT Permit Codes (Trunk Highway Only)................................................... 103

B.6 LOAD RATING RESPONSIBILITY ................................................................................... 103B.6.1 Procedures and Qualifications ........................................................................... 103B.6.2 Responsibility for Performing Load Ratings ...................................................... 103B.6.3 Load Rating Responsibilities of the MnDOT Bridge Office ............................... 104

B.7 LOAD RATING METHODS & FORMS ............................................................................. 104B.7.1 Load Ratings Methods (FHWA Items #63 & 65)................................................ 104B.7.2 MnDOT Bridge Load Rating Forms ................................................................... 105

B.8 LOAD RATING REFERENCES AND LAWS....................................................................... 107

APPENDIX C: SAFETY FEATURES (FHWA ITEM #36)............................................ 108

C.1 FHWA ITEM #36 (TRAFFIC SAFETY FEATURES).......................................................... 108C.2 FHWA ITEM #36A: BRIDGE RAILING.......................................................................... 109

C.2.1 MnDOT Railing Type Codes & Diagrams.......................................................... 110C.3 GUARDRAIL REQUIREMENTS (ROADWAY OVER BRIDGE OR CULVERT) ....................... 127

C.3.1 Approach Guardrail Requirements for Bridges ................................................. 127C.3.2 Guardrail Requirements for Culverts ................................................................. 128

C.4 FHWA ITEM #36B: GUARDRAIL TRANSITIONS ........................................................... 129C.4.1 Guardrail Transition Checklist........................................................................... 130C.4.2 Guardrail Transition Details .............................................................................. 130

C.5 FHWA ITEM #36C: APPROACH GUARDRAIL ............................................................... 134C.5.1 Bridge Approach Guardrail Layouts & Length Requirements........................... 135C.5.2 Structural Plate-Beam (“W-Beam”) Guardrail ................................................. 137

C.6 FHWA ITEM #36D: APPROACH GUARDRAIL ENDS ..................................................... 138C.6.1 Twisted End Treatments...................................................................................... 138C.6.2 Guardrail Terminals and Crash Cushions (Selection Flow Charts) .................. 139C.6.3 Guardrail Terminals and Crash Cushions (Identification Table) ...................... 141


Section 1: Introduction

This manual is intended to serve as a field guide for the inspection and condition rating of in-servicebridges and culverts in Minnesota. This manual includes the NBI condition ratings, structural elementcondition ratings, and other inventory items displayed on the MnDOT Bridge Inspection Report.

A bridge inspection includes examining the structure, evaluating the physical condition of the structure,and reporting the observations and evaluations on the bridge inspection report. MnDOT currently usestwo separate condition rating systems for bridges and culverts - the NBI condition ratings and thestructural element condition ratings…

The NBI condition ratings describe the general overall condition of a bridge (see Section 2). Thisrating system was developed by the Federal Highway Administration (FHWA), and is outlined inthe “FHWA Recording and Coding Guide for the Structure Inventory and Appraisal of theNation’s Bridges”. The NBI condition ratings are used to calculate the Bridge Sufficiency Rating,which determines funding eligibility and priority for bridge replacement and rehabilitation

Structural element condition ratings divide a bridge into separate components which are thenrated individually based upon the severity and extent of deterioration (see Section 3). This ratingsystem was developed by the American Association of State Highway and TransportationOfficials (AASHTO), and is outlined in the “AASHTO Guide for Commonly Recognized (CoRe)Structural Elements”. Structural element condition ratings provide input data for a BridgeManagement System (BMS) which can be used to identify present maintenance needs, and isintended to provide cost-effective options for long-range bridge maintenance and improvementprograms (using computer projections of future deterioration).

This manual was developed by the MnDOT Bridge Office - a PDF version can be downloaded online onthe MnDOT Bridge Office Web site: http://www.dot.state.mn.us/bridge/ - it is listed under “Manuals”.For questions, comments, or corrections, please contact Pete Wilson at (615) 366-4574 or via e-mail [email protected]

http://www.dot.state.mn.us/bridge/



Section 2: NBI Condition Ratings

2.1 NBI Bridge Condition Ratings

The NBI condition ratings describe the general overall condition of a bridge (or culvert) - these ratings aredisplayed on the MnDOT Bridge Inspection Report, and must be reviewed during each inspection. TheNBI ratings are a key component of the “Bridge Sufficiency Rating”, which is used to establish fundingeligibility and priority for bridge replacement and rehabilitation. There are 5 NBI condition ratings - theyare rated on a numerical scale of 1 to 9 (with 9 being “new” condition).

NBI Deck Condition Rating (FHWA Item #58) NBI Superstructure Condition Rating (FHWA Item #59) NBI Substructure Condition Rating (FHWA Item #60) NBI Channel & Channel Protection Condition Rating (FHWA Item #61) NBI Culvert Condition Rating (FHWA Item #62)

A bridge is typically rated in three components (deck, superstructure, and substructure) - if the bridgespans over a waterway, the channel (FHWA Item #61) must also be rated. For filled spandrel arch bridgesor roadway tunnels, the NBI superstructure and substructure items should be rated, but the NBI deckrating may be entered as “N”.

FHWA Item #58 describes the general overall condition of the deck (or slab) - this includes theunderside of the deck and the wearing surface. The railings, curbs, sidewalks, expansion joints,and deck drains should typically not be considered in this rating.

FHWA Item #59 describes the general overall condition of the superstructure - this includes allstructural components (slabs, arches, trusses, girders, or beams) located above (and including) thebearings. This rating should consider any deterioration, misalignment, or collision damage.

FHWA Item #60 describes the general overall condition of the substructure - this includes allstructural components (piers, abutments, pilings, or footings) located below the bearings. Thisrating should consider any settlement, tipping, misalignment, undermining, or scour. Wingwallsor retaining walls (up to the first expansion or construction joint) may be considered in this rating.

Culverts are rated as a single component (FHWA Item #62) - if water flows through a culvert, the channel(FHWA Item #61) must also be rated. FHWA Item #62 describes the general overall condition of theculvert. This rating should consider the condition of the culvert barrel, joints and seams, as well as anydeflection, distortion, misalignment, settlement, scour, or voiding of backfill. Headwalls, wingwalls oraprons (up to the first construction joint) should be included in this rating.

The following general guidelines apply to the NBI Condition Ratings…

New bridges (or culverts) will be assigned an initial NBI rating of “9” (excellent condition). Bridge components that have been repaired should typically not be rated higher than “7” (good

condition). An NBI rating of “5” (fair condition) or less implies that repairs are recommended - NBI ratings

of condition “5” or less will also reduce the bridge sufficiency rating. An NBI rating of “4” (poor condition) or less may impact the required inspection frequency. An NBI rating of “3” (serious condition) or less implies that immediate repairs (or a new load

rating) may be necessary. An NBI rating of “2” (critical condition) typically indicates a critical finding. MnDOT Technical

Memorandum TM-05-02-B-02 outlines reporting and follow-up procedures for a critical finding. Temporary supports (shoring, bracing, or underpinning) should not improve the NBI rating. The load carrying capacity should not be considered when determining the NBI condition ratings.


2.1.1 NBI Deck Condition Rating (FHWA Item #58)

This rating should reflect the overall general condition of the deck (or slab) - this includes the undersideof the deck as well as the wearing surface. The condition of railings, sidewalks, curbs, expansion jointsand deck drains should not be considered in this rating.

Code NBI Deck Condition DescriptionN Not Applicable: Use for culverts, roadway tunnels, or filled spandrel arch bridges.

9 Excellent Condition: Deck is in new condition (recently constructed).

8

Very Good Condition: Deck has very minor (and isolated) deterioration. Concrete: minor cracking, leaching, scale, or wear (no delamination or spalling). Timber: minor weathering - isolated (minor) splitting. Steel: no corrosion (paint/protection system remains sound).

7

Good Condition: Deck has minor (or isolated) deterioration. Concrete: minor cracking, leaching, scale, or wear (isolated delamination, spalling, or

temporary patches). Timber: minor weathering or splitting (no decay or crushing) - all planks are secure. Steel: minor paint failure or corrosion (no section loss) - all connections are secure.

6

Satisfactory Condition: Deck has minor to moderate deterioration (no repairs are necessary). Concrete: moderate cracking, leaching, scale, or wear (minor delamination or spalling). Timber: moderate weathering or splitting (isolated decay or crushing) - some planks

may be slightly loose. Steel: moderate paint failure and/or surface corrosion (minor section loss) - some

connections may have worked loose.

5

Fair Condition: Deck has moderate deterioration (repairs may be necessary). Concrete: extensive cracking, leaching, scale, or wear (moderate delamination or

spalling). Timber: extensive weathering or splitting (moderate decay or crushing) - some planks

may be loose, broken, or require replacement. Steel: extensive paint failure and/or surface corrosion (moderate section loss) - several

connections may be loose or missing, but all deck components remain secure.

4

Poor Condition: Deck has advanced deterioration (replacement or overlay should be planned). Concrete: advanced cracking, leaching, scale, or wear (extensive delamination or

spalling) - isolated full-depth failures may be imminent. Timber: advanced weathering, splitting, or decay - numerous planks may be loose,

broken, or require replacement. Steel: advanced corrosion (significant section loss) - deck components may be loose or

slightly out of alignment.

3

Serious Condition: Deck has severe deterioration - immediate repairs may be necessary. Concrete: severe cracking, leaching, delamination, or spalling - full-depth failures may

be present. Timber: severe splitting, crushing or decay - majority of planks may need replacement. Steel: severe and section loss - deck components may be severely out of alignment.

2Critical Condition: Deck has failed - it may be necessary to close the bridge until repairs arecompleted.

1"Imminent" Failure Condition: Bridge is closed - corrective action is required to open torestricted service.

0 Failed Condition: Bridge is closed - deck replacement is necessary.


2.1.2 NBI Superstructure Condition Rating (FHWA Item #59)

This rating should reflect the overall general condition of the superstructure - this includes all structuralcomponents located above (and including) the bearings.

Code NBI Superstructure Condition DescriptionN Not Applicable: Use for culverts.

9 Excellent Condition: Superstructure is in new condition (recently constructed).

8 Very Good Condition: Superstructure has very minor (and isolated) deterioration.

7

Good Condition: Superstructure has minor (or isolated) deterioration. Steel: minor corrosion, little or no section loss. Concrete: minor scaling or non-structural cracking (isolated delamination or spalling). Timber: minor weathering or splitting (no decay or crushing). Masonry: minor weathering or cracking (joints have little or no deterioration).

6

Satisfactory Condition: Superstructure has minor to moderate deterioration. Members may beslightly bent or misaligned - connections may have minor distress.

Steel: moderate corrosion (section loss or fatigue cracks in non-critical areas). Concrete: moderate scaling or non-structural cracking (minor delamination or spalling). Timber: moderate weathering or splitting (minor decay or crushing). Masonry: moderate weathering or cracking (joints may have minor deterioration).

5

Fair Condition: Superstructure has moderate deterioration. Members may be bent, bowed, ormisaligned. Bolts, rivets, or connectors may be loose or missing, but connections remain intact.

Steel: extensive corrosion (initial section loss in critical stress areas). Fatigue cracks (ifpresent) have been arrested or are not likely to propagate into critical stress areas.

Concrete: extensive scaling or cracking (structural cracks may be present), moderatespalling or delamination (reinforcement may have some section loss).

Timber: extensive weathering or splitting (moderate decay or crushing). Masonry: extensive weathering or cracking (joints may have slight separation or offset).

4

Poor Condition: Superstructure has advanced deterioration. Members may be significantly bentor misaligned. Connection failure may be imminent. Bearings may be severely restricted.

Steel: significant section loss in critical stress areas. Un-arrested fatigue cracks exist thatmay likely propagate into critical stress areas.

Concrete: advanced scaling, cracking, or spalling (significant structural cracks may bepresent - exposed reinforcement may have significant section loss).

Timber: advanced splitting (extensive decay or significant crushing). Masonry: advanced weathering or cracking (joints may have separation or offset).

3

Serious Condition: Superstructure has severe deterioration - immediate repairs or structuralevaluation may be required. Members may be severely bent or misaligned - connections orbearings may have failed.

Steel: severe section loss or fatigue cracks in critical stress areas. Concrete: severe structural cracking or spalling. Timber: severe splitting, decay, or crushing. Masonry: severe cracking, offset or misalignment.

2Critical Condition: Superstructure has critical deterioration - primary structural elements mayhave failed (severed, detached or critically misaligned). Immediate repairs may be required toprevent collapse or closure.

1"Imminent" Failure Condition: Bridge is closed - superstructure in no longer stable (correctiveaction might return the structure to restricted service).

0 Failed Condition - Bridge is closed - superstructure is beyond the point of corrective action.


2.1.3 NBI Substructure Condition Rating (FHWA Item #60)

This rating should reflect the overall general condition of the substructure - this includes all structuralcomponents located below the bearings.

Code NBI Substructure Condition DescriptionN Not Applicable: Use for culverts.

9 Excellent Condition: Substructure is in new condition (recently constructed).

8 Very Good Condition: Substructure has very minor (and isolated) deterioration.

7

Good Condition: Substructure has minor (or isolated) deterioration. Concrete: minor cracking, leaching, or scale (isolated delaminations or spalls). Steel: minor paint failure and/or surface corrosion (little or no section loss). Timber: minor weathering or splitting (no decay or crushing). Masonry: minor weathering or cracking (joints have little or no deterioration).

6

Satisfactory Condition: Substructure has minor to moderate deterioration. Scour or erosion (ifpresent) is minor and isolated. There may be slight movement or misalignment.

Concrete: moderate scaling, cracking, or leaching (minor delamination or spalling). Steel: moderate paint failure and/or surface corrosion (minor section loss). Timber: moderate weathering or splitting (minor decay or crushing). Masonry: moderate weathering or cracking (joints may have minor deterioration).

5

Fair Condition: Substructure has moderate deterioration - repairs may be necessary. There maybe moderate scour, erosion, or undermining. There may be minor settlement, movement,misalignment, or loss of bearing area.

Concrete: extensive scaling, cracking or leaching (isolated structural cracks may bepresent) - there may be moderate delamination or spalling.

Steel: extensive paint failure and/or surface corrosion (moderate section loss). Timber: extensive weathering or splitting (moderate decay or crushing). Masonry: extensive weathering or cracking (joints may have slight separation or offset).

4

Poor Condition: Substructure has advanced deterioration - repairs may be necessary to maintainstability. There may be extensive scour, erosion, or undermining. There may be significantsettlement, movement, misalignment, or loss of bearing area.

Concrete: advanced scaling, cracking, or leaching (significant structural cracks may bepresent) - there may be extensive delamination or spalling.

Steel: advanced corrosion (significant section loss). Timber: advanced splitting (significant decay or crushing). Masonry: advanced weathering or cracking (joints may have separation or offset).

3

Serious Condition: Substructure has severe deterioration. Immediate corrective action may berequired. Scour, erosion, or undermining may have resulted in severe settlement, movement,misalignment, or loss of bearing area.

Concrete: severe spalling or structural cracking. Steel: severe section loss. Timber: severe decay or crushing. Masonry: severe cracking, offset or misalignment.

2Critical Condition: Substructure has critical damage or deterioration (near the point of collapse)- it may be necessary to close the bridge until corrective action is completed. Scour may haveremoved substructure support.

1Imminent Failure Condition: Bridge is closed to traffic due to substructure failure - correctiveaction may restore the bridge to light service.

0Failed Condition: Bridge is closed due to substructure failure - beyond corrective action(replacement required).


2.1.4 NBI Channel/Channel Protection Condition Rating (FHWA Item #61)

This rating should reflect the overall general condition of the waterway flowing below the bridge (orrunning through the culvert) - even if the channel is occasionally dry. This rating can be based uponfindings from routine visual inspections, soundings, or underwater inspections.

This rating includes the channel and banks below the bridge, as well as immediately upstream anddownstream of the bridge (typically those areas visible from the bridge). Changes in the channel - such asaggradation (rising of the channel due to sedimentation), degradation (lowering of the channel due toerosion), or lateral stream migration that might adversely affect the bridge should be considered in thisrating. The presence drift in the channel, debris lodged against the bridge, or sediment inside culvertbarrels should also be considered in this rating. Note: if the bridge is over a navigable waterway (FHWAItem #38 coded as “1”), the condition of substructure protection devices (such as dolphins, fenders, andshear walls) must be rated using FHWA Item #111.

Code NBI Channel Condition DescriptionN Not Applicable: Bridge is not over a waterway.

9 Excellent Condition: There are no noticeable or noteworthy deficiencies.

8Very Good Condition: Channel banks are protected (or well vegetated) - there is little or noerosion. Control structures and protection devices (if present) have little or no deterioration. Anydrift or debris in the channel is incidental. Culvert barrel has little or no sediment.

7

Good Condition: Channel has no notable aggradation, degradation, or lateral movement. There isno notable scour around the bridge substructure. The banks may have minor erosion - bankprotection (if any) may have minor deterioration. Control structures and/or protection devicesmay have minor deterioration. There may be minor drift or debris in the channel. Culvert barrelmay have minor sediment.

6

Satisfactory Condition: Channel may have minor aggradation, degradation, or lateral movement.The channel banks may have moderate erosion or slumping - bank protection may have moderatedeterioration. Control structures and/or protection devices may have moderate deterioration. Driftor debris in the channel may be slightly restricting the channel. Culvert barrel may have moderatesediment.

5

Fair Condition: Channel may have moderate aggradation, degradation, or lateral movement, butthe bridge and approaches have not yet been adversely affected. The channel banks may haveextensive erosion - the bank protection may have extensive deterioration. Control structuresand/or protection devices may have extensive deterioration, but are functioning as intended.Debris in the channel (or sediment in the culvert barrel) is restricting the channel and should beremoved.

4

Poor Condition: Aggradation, degradation, or lateral movement of the channel may be adverselyaffecting the bridge and/or approaches. Channel banks may have severe erosion - the bankprotection may have severe deterioration. Control structures and/or protection devices may bedeteriorated to the extent that they are no longer functioning as intended. Large accumulations ofdebris or sediment are severely restricting the channel, and should be removed immediately.

3Serious Condition: Aggradation, degradation, or lateral movement has altered the channel to theextent that the bridge (or approach roadway) is threatened. Bank protection has failed. Controlstructures and/or protection devices have been destroyed.

2Critical Condition: Aggradation, degradation, or lateral movement has altered the channel to theextent that the bridge is near a state of collapse. It may be necessary to close the bridge untilcorrective action is completed.

1 Bridge closed due to channel failure: Corrective action may restore bridge to light service.

0 Bridge closed due to channel failure: Replacement necessary.


2.1.5 NBI Culvert Condition Rating (FHWA Item #62)

This rating should reflect the overall general condition of the culvert. If a structure is classified as a“culvert”, the NBI condition ratings for deck, superstructure, and substructure must all be rated as “N”.

Code NBI Culvert Condition DescriptionN Not Applicable: Structure is not a culvert.

9 Excellent Condition: Culvert is new condition (recently constructed).

8 Very Good Condition: Culvert has very minor (and isolated) deterioration.

7

Good Condition: Culvert has minor (or isolated) deterioration. Joints are sound and properlyaligned (no leakage or backfill infiltration). Footings have no undermining.

Concrete/Masonry: minor weathering/scaling, cracking, or leaching (isolated spalling) Steel: minor corrosion (little or no section loss) - barrel has no distortion. Timber: minor splitting (no decay, crushing, or sagging).

6

Satisfactory Condition: Culvert has minor to moderate deterioration. Joints may have minorseparation or misalignment (slight leakage or backfill infiltration).

Concrete/Masonry: moderate weathering/scaling, cracking, or leaching (minor spalling). Steel: moderate corrosion (minor section loss) - barrel may have minor distortion (seams

may have minor distress, but no cracking). Timber: moderate splitting (minor decay, crushing, or sagging).

5

Fair Condition: Culvert has moderate deterioration - repairs may be required, but the culvert isstructurally sound and functioning as intended. Joints may have separation or misalignment(moderate leakage or backfill infiltration). Footings may be partially undermined (minorsettlement). Embankments remain intact (roadway has no notable settlement).

Concrete/Masonry: extensive weathering/scaling, cracking, or leaching (moderatespalling).

Steel: extensive corrosion (any significant section loss is isolated) - barrel may havemoderate distortion (seams may have missing bolts or isolated cracking).

Timber: extensive splitting (moderate decay, crushing, or sagging).

4

Poor Condition: Culvert has advanced deterioration - structural evaluation or repairs may benecessary (the structural integrity and/or functional capacity of the culvert may be slightlyreduced). Footings may have significant undermining or settlement. Loss of backfill may haveresulted in slight settlement of the roadway or embankment.

Concrete/Masonry: advanced weathering, cracking, leaching, or scaling (significantspalling). Joints may have significant separation, misalignment, or leakage.

Steel: advanced corrosion (significant section loss) - barrel may have significantdistortion (seams may have extensive cracking or isolated failures).

Timber: advanced splitting (significant decay, crushing, or sagging).

3

Serious Condition: Culvert has serious deterioration - immediate repairs or corrective action maybe required (the structural integrity and/or functional capacity of the culvert may be significantlyreduced). Joints may have severe deterioration, misalignment, offset, separation, or leakage. Lossof backfill may have resulted in significant settlement or undermining of the roadway orembankment. Footings may have severe undermining or settlement.

Concrete/Masonry: severe weathering, cracking, or spalling. Steel: severe section loss - barrel may have severe distortion (seams may have failed). Timber: severe decay, crushing, or sagging.

2Critical Condition: Culvert has critically advanced deterioration (near the point of collapse) - itmay be necessary to close the roadway until corrective action is completed.

1 "Imminent" Failure Condition: Culvert is closed - corrective action may restore to light service

0 Failed Condition: Culvert is closed - replacement is necessary.


2.2 Bridge Appraisal Ratings & Other Items

The MnDOT Bridge Inspection Report displays two of the NBI Bridge Appraisal Ratings, as well assome additional structure inventory items. This section includes explanations of some of these items -they should be periodically reviewed for accuracy.

2.2.1 Waterway Adequacy Appraisal Rating (FHWA Item #71)

This rating is a general assessment of the waterway opening with respect to the passage of flow throughthe bridge. This rating is based upon the frequency of “overtopping” of the bridge and approach (and theresultant traffic delays). The functional class of the roadway is also taken into consideration. Siteconditions may warrant somewhat higher or lower ratings than indicated by the table (e.g. flooding of anurban area due to a restricted bridge opening). Note: when a new bridge or culvert is added to theMnDOT bridge database, this item will initially be coded as “9” - as this coding may not be appropriate,this item should always be reviewed for new bridges.

The descriptions given in the table mean the following…

Chances of Overtopping Traffic DelaysRemote: greater than 100 years Insignificant: Minor inconvenience (impassable for a few hours)Slight: 11 to 100 years Significant: Traffic delays of up to several daysOccasional: 3 to 10 years Severe: Long-term traffic delays with resulting hardshipFrequent: less than 3 years

“Freeboard” is defined as the distance from the bottom of the superstructure to the water surface (at thewater level of the 50-year frequency design storm).

Waterway Adequacy Appraisal Rating (FHWA Item #71)Functional Classification

DescriptionPrincipal Arterials

- Interstates,Freeways, orExpressways

Other Principal andMinor Arterial andMajor Collectors

Minor Collectorsand Local Roads

N N N Bridge not over a waterway.

9 9 9Bridge deck and roadway approaches above floodwater

elevations (high water). Chance of overtopping is remote.

8 8 8Bridge deck above roadway approaches. Slight chance of

overtopping roadway approaches. Greater than 3 ft. offreeboard.

6 6 7Bridge deck above roadway approaches. Slight chance of

overtopping bridge deck and roadway approaches. 2 to 3 ft. offreeboard.

4 4 6Bridge deck above roadway approaches. Occasional

overtopping of roadway approaches with insignificant trafficdelays. 1 to 2 ft. of freeboard.

3 4 5Bridge deck above roadway approaches. Occasional

overtopping of roadway approaches with significant trafficdelays. Less than 1 ft. of freeboard.

2 3 4Occasional overtopping of bridge deck and roadway

approaches with significant traffic delays.

2 2 3Frequent overtopping of bridge deck and roadway approaches

with significant traffic delays.

2 2 2Occasional or frequent overtopping of bridge deck and

roadway approaches with severe traffic delays.

0 0 0 Bridge closed.


2.2.2 Approach Roadway Alignment Appraisal Rating (FHWA Item #72)

FHWA Item #72 is a general assessment of the approach roadway alignment - this item identifies thosebridges that do not function properly or adequately due to the approach alignment. While this rating willtypically remain constant, it should be reviewed if the bridge approaches have been reconstructed. Thisrating only applies to the roadway passing over the bridge (not the roadway passing below the bridge).

Railroad or pedestrian bridges crossing over a roadway should be coded as “N”.

Note: when a new bridge or culvert is added to the MnDOT bridge database, this item will initially becoded as “9” - an appropriate coding should be determined for any structure currently coded as “9”.

This rating is based upon the speed reduction required (due to the vertical or horizontal approachalignment) by a typical vehicle using the roadway. Note: Speed reductions necessary due to structurewidth shall not be considered when evaluating this item.

Approach Roadway Alignment Appraisal Rating (FHWA Item #72)

Code Description

N Not Applicable (use for railroad or pedestrian bridges)

9 New Structure - an appropriate rating code should be determined

8 No speed reduction required

7 Minor sight distance problems with no speed reduction required

6 Very minor speed reduction required (0-3 MPH for a typical vehicle using the roadway)

5 Minor speed reduction required (3-5 MPH for a typical vehicle using the roadway)

4 Significant speed reduction required (5-10 MPH for a typical vehicle using the roadway)

3 Intolerable alignment requiring a substantial reduction in the operating speed (10-20MPH for a typical vehicle using the roadway)

2Severe vertical or horizontal alignment problems, such as a sharp vertical or horizontalcurve immediately adjacent to the bridge (Speed reduction of 20 MPH or greater for a

typical vehicle using the roadway)

1 This rating code should not be used

0 Bridge Closed


2.2.3 Bridge Deficiency Status

If a bridge or culvert has been designated as Structurally Deficient or Functionally Obsolete, this will bedisplayed on the MnDOT Bridge Inspection Report. These two items should be automatically calculated -any discrepancies should be reported to the MnDOT Bridge Office Bridge Management Unit.

The FHWA designates a bridge as “Structurally Deficient” if it meets one of the following conditions:

1. An NBI condition rating of “4” or less for the Deck (FHWA Item #58), Superstructure (FHWAItem #59), Substructure (FHWA Item #60), or Culvert (FHWA Item #62); or

2. A rating of “2” or less for the Structural Evaluation Appraisal Rating* (FHWA Item #67); or3. A rating of “2” or less for the Waterway Adequacy Appraisal Rating (FHWA Item #71)

*The Structural Evaluation Appraisal Rating (FHWA Item #67) is automatically calculated. A newbridge load capacity rating that significantly reduces the inventory load rating (FHWA Item #66)may result in a bridge being designated as “structurally deficient”.

Note: the FHWA recently established a "10-year rule" that prevents bridges from remaining classified as“structurally deficient” after a major reconstruction project. Bridges with a “Year Built” date (FHWAItem #27) or “Year Reconstructed” date (FHWA Item #106) within the past 10 years will not beconsidered to be a deficient bridge, and will not be eligible for Federal Highway Bridge Replacement andRehabilitation Program funds.

The FHWA designates a bridge as “Functionally Obsolete” if it meets one of the following conditions:

1. A rating of “3” or less for the Deck Geometry Appraisal Rating (FHWA Item #68); or2. A rating of “3” or less for the Underclearance Appraisal Rating (FHWA Item #69); or3. A rating of “3” or less for the Approach Alignment Appraisal Rating (FHWA Item #72); or4. A rating of “3” for the Structural Evaluation Appraisal Rating (FHWA Item #67); or5. A rating of “3” for the Waterway Adequacy Appraisal Rating (FHWA Item #71)

Note: a bridge designated as “structurally deficient” is excluded from consideration as being“functionally obsolete”. As the many of the bridge appraisal ratings are automatically calculated basedupon existing structure inventory items, inventory coding errors could result in a bridge being incorrectlydesignated as “functionally obsolete”.

2.2.4 Bridge Sufficiency Rating

The bridge sufficiency rating is a based upon a percentage scale of 0%-100% (with 100% being an entirelysufficient bridge). The bridge sufficiency rating is used to establish funding eligibility and priority forbridge replacement and rehabilitation. As a general rule, a sufficiency rating of 80% or less is required tobe eligible for bridge rehabilitation, and a sufficiency rating of 50% or less is required to be eligible forbridge replacement.

The bridge sufficiency rating takes into consideration the structural adequacy, functional capacity, andessentiality for public use of the bridge (the formula is explained in detail in Appendix B of the FHWARecording & Coding Guide). While the NBI condition ratings are a key component of the bridgesufficiency rating, only NBI superstructure, substructure, or culvert condition ratings of “5” or less willsignificantly reduce the bridge sufficiency rating. Other factors used to calculate the bridge sufficiencyrating include the inventory load-carrying capacity, the NBI appraisal ratings, the average daily traffic(ADT), FHWA Item #36 (safety features), and the detour length.

Note: The bridge sufficiency rating should be automatically calculated for bridges (or culverts) that carryvehicular traffic - any discrepancies should be reported to the MnDOT Bridge Office Bridge ManagementUnit. The bridge sufficiency rating is not calculated for railroad or pedestrian bridges.


2.2.5 MnDOT Scour Codes and Channel Cross-Sections

The MnDOT scour code indicates the bridge’s vulnerably to scour - the scour code (along with anabbreviated description) is displayed on MnDOT Inspection Report. The MnDOT scour codes, along withthe corresponding rating for FHWA Item #113 (Scour Critical Bridges), are shown below…

MnDOT Scour Code Descriptions(corresponding coding for FHWA Item #113 shown at right)

MnDOTScourCode

DescriptionFHWA

Item#113

A Bridge is not over a waterway. N

GScour calculation, evaluation and/or screening have not been made. Bridge on

unknown foundations. U

H Bridge foundations (including piles) are well above flood water elevations. 9

E Culvert structure: Scour calculation, evaluation, and/or screening have not been made.

8I Bridge screened, determined to be low risk for failure due to scour.

MBridge foundations determined to be stable for calculated scour conditions; calculated

scour depth from the scour prediction equations is above top of footing.

P

Countermeasures have been installed to correct a previously existing problem withscour. Bridge is no longer scour critical. Scour countermeasures should be inspected

during routine inspections (when above water of accessible by wading), duringunderwater inspections, after major flows, or as recommended in the Scour Action

Plan. Report any changes that have occurred to countermeasures.

7

CBridge is closed to traffic for reasons other than scour. Prior to reopening, the bridge

must be evaluated for scour and the scour code must be updated.

6K

Bridge screened, determined to be of limited risk to public, monitor in lieu ofevaluation and close if necessary.

F Bridge structure: Scour calculation, evaluation, and/or screening have not been made.

JBridge screened - determined to be scour susceptible (further evaluation must be

completed). All substructure foundations are known.

L Scour evaluation complete, bridge judged to be low risk for failure due to scour.

5N

Bridge foundations determined to be stable for calculated scour conditions; calculatedscour depth from the scour prediction equations is within limits of footing or piles.

OBridge foundations determined to be stable for predicted scour conditions; Scour

Action Plan requires additional action. 4

RBridge has been evaluated and is scour critical. Scour Action Plan recommends

monitoring the bridge during high flows and closing if necessary. 3

DBridge is scour critical; field review indicates that extensive scour has occurred at

bridge foundations. Immediate action is required to provide scourcountermeasures. Note: this scour code is equivalent to a critical finding.

2

UBridge has been evaluated and is scour critical. Scour Action Plan recommends this

bridge as a priority for installation of countermeasures. Until countermeasures areinstalled, monitor bridge during high flows and close if necessary.

BBridge is closed to traffic; field review indicates that failure of piers and/or abutments

due to scour is imminent or has occurred. 1


MnDOT Scour Evaluation Process

The FHWA requires that all vehicular bridges over water with a total length greater than 20 feet bereviewed for scour. In Minnesota, this process consists of a primary and secondary scour screening - andif necessary, a more thorough scour evaluation. The “Bridge Scour Evaluation Procedure forMinnesota Bridges” can be downloaded on the MnDOT Bridge Office web site - this outlines the scourscreening and evaluation process, and includes templates for developing “Scour Plans of Action”.

If the MnDOT scour code is “F, G, or J” (and the total structure length exceeds 20 ft.) - additionalscour analysis (and re-coding) is required.

If the MnDOT scour code is “G, K, O, P, R, or U”, a “Scour Plan of Action” must be establishedto outline procedures for monitoring or closing the bridge during high water events. Each agencyshould maintain a file or notebook containing all of their Scour Plans of Action that is readilyavailable for review during a high water or flood event.

During the scour screening and evaluation process, bridges were coded as low risk based upon theassumption that there were no existing scour problems (or history of scour), and that abutment slopeswere adequately protected. If scour or channel problems develop on a bridge coded as “low risk” or“limited risk”, the scour coding should be revised.

It is the responsibility of the agency with inspection jurisdiction for a bridge to perform scour screeningsand evaluations, and to determine the appropriate MnDOT scour code. If a MnDOT scour code is revised,the MnDOT Bridge Office Bridge Management Unit should be notified so that the code (and year ofscour evaluation) can be properly updated. The agency with inspection jurisdiction should retain alldocumentation pertaining to scour screenings, evaluation, and coding. Note: FWHA Item #113 (ScourCritical Bridges) is not currently displayed on the Mn//DOT Bridge Inspection Report or the StructureInventory Report - FHWA #113 is automatically calculated from the MnDOT Scour code.

Channel Cross-Sections

A channel cross-section is a series of channel bottom elevation measurements taken across the channel(perpendicular to the direction of flow) - these are typically taken along the edge of the bridge deck.Channel cross-sections are useful tools for identifying scour problems or long-term changes in thechannel, such as aggradation, degradation, or channel migration. The AASHTO Manual for BridgeEvaluation (Section 2.4.1) recommends that bridge files contain information relating to the channelcross-sections…

Channel cross-sections should be taken and a sketch developed to become part of the bridge record.The sketch should show the foundation of the structure and, where available, a description of materialupon which footings are founded, the elevation of the pile tips, the footings of piers and abutment, orany combination thereof. This information is valuable for reference in anticipating possible scourproblems through periodic observation and is especially useful to detect serious conditions duringperiods of heavy flow. The use of aerial photography, when used to monitor channel movement, shouldalso become part of the bridge record.

Channel cross-sections from current and past inspections should be plotted on a common plot toobserve waterway instability such as scour, lateral migration, aggradation, or degradation. Verticalmeasurements should be made or referenced to a part of the structure such as the top of curb or top ofrailing that is readily accessible during high water.

Soundings and multiple cross-sections may be necessary to provide adequate information on waterwayinstability and how the structure may be affected. Such requirements will vary with the stream velocityand general channel stability. The necessity of additional soundings must be determined by theEngineer. These soundings will normally be limited to an area within a radius of 100 feet from a pier.


MnDOT Criteria and Minimum Frequencies for Performing Channel Cross-Sections

While a routine bridge inspection will include examining piers and abutments for scour (by probing thosesubstructure units that are accessible by wading), channel cross-sections are not necessarily performedduring routine inspections. MnDOT has developed the following criteria for determining which bridgesrequire channel cross-sections, and establishing a minimum frequency for performing channel cross-sections. More frequent channel cross-sections (or supplemental soundings) may be needed if significantscour problems exist, or if specified in the Scour Plan of Action. Channel cross-sections arerecommended during or immediately after high water events, or if a significant change in the streambed isobserved.

Channel cross-sections are required for the following vehicular bridges…

1. Bridges classified as “Scour Critical” (MnDOT scour codes “D”, R” or “U”).2. Bridges with an NBI Channel Condition Rating (FHWA Item #61) of “3”.

If channel cross-sections are required according to the criteria above, they should be performed at aminimum frequency of 5 years.

Note: Any bridge included with a state-wide underwater inspection contract will have a channelcross-section performed as part of the contract, regardless of the MnDOT Scour Code. The agencywith inspection jurisdiction is responsible for performing all required channel cross-sections forthose bridges not included in a state-wide underwater bridge inspection contract.

Channel cross-sections are recommended for the following bridges…

1. Bridges over 20 ft. in length with a MnDOT scour code of “G” (unknown foundations)2. Bridges over 20 ft. in length with a MnDOT scour code of “J” (scour susceptible).3. Any bridge with an NBI Channel Condition Rating (FHWA Item #61) of “4”.4. Any bridge with a Scour Smart Flag rating (structure element #361) of condition “2” or “3”.5. If cross-section measurements are recommended in the Scour Plan of Action.

If channel cross-sections are recommended (according to the criteria above), the agency withinspection jurisdiction should establish an appropriate frequency - this will vary depending upon suchfactors as the stream volume and velocity, structure type and site conditions.

Channel Cross-section Procedures, Equipment and Documentation

At a minimum, a channel cross-section shall be taken along the upstream and/or downstream face of thebridge. Channel bottom elevation measurements should be taken at a sufficient number of locations alongthe bridge to obtain a representative channel cross-section which can be compared to past and futurecross-sections. At a minimum, this shall include channel bottom elevation measurements at eachsubstructure unit and at the center of each span. On longer spans, establishing specific measurementlocations along the bridge can speed up data collection and will make it easier to compare to past andfuture measurements.

Channel bottom elevation measurements may be obtained by using a sounding rod, weight, sonar, orsurvey equipment. The type of equipment used will often be dictated by the water depth and velocity(sonar readings may not be possible in turbulent water). A benchmark elevation should be clearly markedon the curb or railing (or another easily accessible location on the bridge), so that channel bottomelevations can be easily determined from depth readings. Elevation measurements are generally recordedto the nearest tenth of a foot.

Channel cross-section measurements shall be documented in the bridge file so that past data can bereadily accessed and compared to present measurements. For large bridges, or bridges over large rivers,lakes, or streams - a cross-section diagram (a graphical display of the actual streambed elevation) isrecommended. A reference cross-section diagram should be established showing the original (plan)


channel cross-section - this should include the substructure foundation elevations. For smaller bridges, orbridges over smaller streams with a relatively stable history - channel cross-section measurements may bedocumented in a table. If only a few measurement locations are required, they can be included in thebridge inspection notes (general notes section).

This channel cross-section diagram shows how the main channel of the Minnesota River shifted dramaticallyduring flooding in 1965, severely undermining the second pier from the left.

Follow-up Actions for Channel Cross-Sections

By performing channel cross-section measurements on regular intervals (and during floods), scour orchannel problems can be identified and corrected before they threaten the structural integrity of the bridgeor approach fill. Problems which might not be obvious during an inspection may be more apparent whencomparing past and present cross-section measurements

Any significant scour or channel problems discovered during an inspection, or determined through thecomparison of channel cross-sections should be promptly reported to the Bridge Inspection ProgramAdministrator. This includes streambed elevations below the substructure footings or seals (or below thecritical scour depth specified in the Scour Plan of Action), undermined footings, exposed foundationpiling, failure of scour countermeasures or slope protection, loss of abutment backfill, or notable shiftingor lowering of the channel.

Note: to ensure that channel cross-sections are performed at the required (or recommended) frequency,the date of the most recent channel cross-section measurements should be noted in the bridge inspectionreport (general notes section).

2.2.6 Structure Open, Posted, or Closed to Traffic (FHWA Item #41)

FHWA Item #41 describes the current operational status of the structure (opened, posted, or closed totraffic). The inspector should verify that this item correctly coded - the item is coded as follows (anabbreviated description will be displayed on the MnDOT Inspection Report).

Code DescriptionA Bridge is open to traffic (no load restrictions) - this includes pedestrian or railroad bridges.

BBridge is open to traffic - load posting is recommended but has not been legally implemented

(all signs not in place).

D Bridge is open to traffic, but would be posted or closed without temporary shoring or supports.

EBridge is open to traffic, but is a temporary structure intended to carry legal loads until the

original structure is rehabilitated (or a new structure is constructed).

G New structure - not yet open to traffic.

K Bridge is closed to all traffic.

PBridge is posted with a load restriction. This includes bridges with more than one restriction,

or temporary bridges with a load restriction.

RBridge is posted with other load-capacity restrictions (such as speed, number of vehicles on

bridge, etc.).

MnDOT BRID20

2.2.7 Bridge Signage (Required)

The bridge inspection report displays any signage (load posting, traffic control, horizontal control, orvertical clearance) required at the bridge site. This is based upon current structure inventory information -it is the responsibly of the agency with inspection jurisdiction to verify these signing requirements. Signstandards and guidelines are outlined in the MnDOT Traffic Engineering Manual and the MinnesotaManual on Uniform Traffic Control Devices. Any signage item listed as “unknown” should be revised.

Load Posting Signs: Minnesota Administrative Rule 8810.9600 requires that a bridge must be posted ifthe “maximum legal load under state law exceeds the load permitted on the structure under the operatingstress level”. If a load rating determines that a weight restriction is required on a bridge or culvert, thetype of load posting sign (as well as the specific posting limits) will be displayed on the header of theMnDOT Bridge Inspection Report - the actual posting should be the same as that displayed on theinspection report. Note: see Appendix B for more information on load capacity ratings. The load postingsign types are coded and displayed as follows…

Load Posting Signage (Required)Code Description Display

0 No Load Posting Signs are Required NOT REQUIRED1 Vehicle Limit Only (type R12-1A) VEHICLE ONLY2 Vehicle and Semi-Trailer Limits (type R12-5) VEHICLE & SEMI3 Bridge Closed (type R11-2A) BRIDGE CLOSED4 Permit Weight Limit (type R12-X11) PERMIT5 Specialized Hauling Vehicle Weight Limit (type R12-5A) SHV

Load posting signs (R12-1A, R12-5, R12-X11 or R12-5A) must be placed either on or immediately infront of the bridge. Advanced signs (R12-5 Supplement or R12-X2) should be placed at the nearestintersecting road (or a wide point in the road) at which an overweight vehicle can detour or turn around.

R12-X1136” x 36”

30” x 36”

24” x 26”

R12-5Supplements

30” x 9”

R12-5A24” x 24”30” x 30”

R12-5

R12-1A

GE INSPECTION MANUAL

36” x 36”

R12-X260” x 36”


Traffic Control Signs: Some bridges require regulatory traffic control signs that may or may not berelated to weight restrictions. Requirements for traffic control signs are coded and displayed as follows…

Traffic Control Signage (Required)Code Description Display

0 No Traffic Restriction Signs Required NOT REQUIRED

1 Bridge Speed Limit (Type R2-X5) SPEED LIMIT

2 Lane Restriction (Trucks/Vehicles Must Not Meet on Bridge) ONLY 1 TRUCK

3 Combination of 1 & 2 SPEED LIMIT & 1 TRUCK

If it is determined that a “Bridge Speed Limit” sign (type R2-X5) is required, they shall be placed 100 ft.from each end of the structure (see Minnesota Statute 169.16 and Section 2B.13.1 of the MinnesotaManual on Uniform Traffic Control Devices).

As outlined in Section 2B.49 of the Minnesota Manual on Uniform Traffic Control Devices), a“Trucks Must Not Meet on Bridge” sign (type R12-X3) should be installed in advance of bridgescarrying 2-way traffic if…

1. The bridge roadway width is more than 18 ft. and less than 20 ft., the approach alignment is poor,and the structure type is such that commercial vehicles cannot pass safely on the bridge, or

2. Where a restriction on the meeting or passing of commercial vehicles would increase the loadcapacity of the structure.

As outlined in Section 2B.49 of the Minnesota Manual on Uniform Traffic Control Devices), a“Vehicles Must Not Meet on Bridge” sign (type R12-X3A) should be installed in advance of bridgescarrying 2-way traffic if the bridge roadway width is 18 ft. or and less.

R2-X524” x 36”

R12-X336” x 24”

R12-X3A42” x 24”

Horizontal Control Signs: Horizontal control signs are coded and displayed as follows…

Horizontal Clearance Signage (Required)Code Description Display

0 No Horizontal Clearance Signs Required NOT REQUIRED1 Type 3 Object Markers(Hazard Markers) OBJECT MARKERS2 Width Restrictions (Narrow Bridge or One Lane Bridge) WIDTH RESTRICTION3 Combination of 1 & 2 OBJECT MARKERS & WIDTH

Obstructions such as abutments, piers, trusses, or railings located within the width of the approachshoulders should be delineated by Object Markers (see Section 3C.3 of the Minnesota Manual onUniform Traffic Control Devices).Type 3 Object Markers (OM-3L, OM-3C, or OM-3R) are typicallyused for bridges - these signs have alternating black & yellow stripes sloping downward toward the sideof the obstruction on which traffic is to pass. The inside edge of the object marker should be in line withthe inner edge of the obstruction.

As outlined in Sectio“Narrow Bridge” si

1. The structurewidth is less

2. The roadwayapproach sho

As outlined in SectioLane Bridge” sign (the bridge deck clear

OM-3L

(12” x 36”)

W5-2(36” x 36”)

n 2C.16 of the Mgn (type W5-2 o

carries 2-way tthan the approacclearance on thulder width is n

n 2C.17 of the MW5-3) should beance width is les

OM-3C

22

innesota Manual onr W5-2A) should be pl

raffic, has a bridge dech roadway width, or

e bridge deck is less thot included)

innesota Manual onplaced in advance of bs than 18 ft.

OM-3R

Type 3 Object Markers

MnDOT BRIDGE INSPECTION MANUAL

Uniform Traffic Control Devices), aaced in advance of a bridge (or culvert) if…

k width greater than 18 ft, but the bridge deck

an the width of the approach travel lanes (the

Uniform Traffic Control Devices), a “Oneridges (or culverts) carrying 2-way traffic if

W5-3(36” x 36”)


Vertical Clearance Signs: Requirements for vertical clearance signs are coded and displayed asfollows…

Vertical Clearance Signage (Required)Code Description Display

N Not Applicable (no vertical restrictions) NOT APPLICABLE

0 No Vertical Clearance Signs Required (14’-6” or greater) NOT REQUIRED

1Vertical Clearance Restriction on Roadway

(type W12-2 or W12-2p)ROADWAY RESTRICTION

2Vertical Clearance Restriction on Shoulder

(Arch Bridges - type W12-X2)SHOULDER RESTRICTION

The maximum vehicle height in the state of Minnesota is 13’-6”. Based upon Section 2C.22 of theMinnesota Manual on Uniform Traffic Control Devices, the “Low Clearance” (W12-2) sign shall beinstalled if vertical clearance under a bridge is less than 14’-6”. Low clearance signs may be installed onor in advance of the structure - if the sign is mounted on the bridge, it must rectangular (W12-2p). If thevertical clearance is less than the legal maximum vehicle height (13’-6”), advanced warning signs (W12-2with a supplemental distance plaque) should be placed at the nearest intersecting road (or wide point inthe road) at which an over height vehicle can detour or turn around.

Low clearance signs should display the vertical clearance to the nearest 1” (not exceeding the actualclearance). In areas where roadways are subjected to frost heave, an allowance of up 3” may be reflectedin the signing. For example, if the actual clearance is 13’-9”, the signs might read 13’-6”.

Bridge clearance measurements should be performed periodically, especially if the roadway has beenresurfaced. The posted clearance should be noted on the inspection report to verify that it correlates withthe structure inventory.

On arch bridges (or when the underclearance varies greatly), the W12-X-2 Vertical Clearance sign shallbe used (the arrow indicates the location of the height specified on the sign).

W12-236” x 36”

W12-2P84” x 24”

W12-X248” x 24”


2.2.8 Roadway Area & Unsound Wearing Surface Percentage

The MnDOT Bridge Inspection Report header displays the roadway area on the bridge deck (“Rdwy.Area”), followed by the percentage of unsound wearing surface (“Pct. Unsnd”).

The “Roadway Area” quantity is only displayed for bridges (not culverts or tunnels). It is expressedin square feet, and is determined by multiplying the curb-to curb (or rail-to-rail) width on thebridge (excluding median) by the total bridge length. On highway bridges with sidewalks, thesidewalk is not included in this quantity. This quantity may also be displayed for pedestrianbridges (sidewalk width multiplied by the bridge length).

The “Unsound Wearing Surface Percentage” indicates the amount of unsound (deteriorated) wearingsurface, expressed as a percentage of the total deck area. This item applies only to concrete decks andslabs, and should correlate with the concrete deck (or slab) structural element rating.

“Unsound” wearing surface includes areas with delamination, spalling, potholes, severe scale, or othersignificant deterioration. Temporary patches should be considered to be “unsound”. Higher quality (long-term) patches should not necessarily be considered “unsound” until they have begun to deteriorate. Thisquantity may be estimated from field observations, or calculated from a deck condition survey (such aschaining or ground penetrating radar).

2.2.9 Painted Area & Unsound Paint Percentage

The MnDOT Bridge Inspection Report header displays the total surface area of painted structural steel(“Paint Area”), followed by the percentage of unsound paint (“Pct. Unsnd”).

The “Painted Area” quantity is only displayed for bridges with a painted steel superstructure. It isexpressed in square feet, and includes steel structural members such as beams, trusses, arches, andsecondary bracing (bridge railings are not included). Note: on bridges constructed of unpaintedweathering steel, only the “high corrosion areas” (typically those areas within 7 ft. of a deck joint)should be considered when determining the total painted area.

The “Unsound Paint Percentage” indicates the estimated quantity of “unsound” (deteriorated) paint,expressed as a percentage of the total painted area. “Unsound” paint includes areas with complete paintsystem failure (exposed and rusted metal), or areas with finish coat deterioration (flaking, cracking, orblistering).


Section 3: Structural Element Condition Ratings

3.1 Introduction to Structural Element Condition Ratings

3.1.1 Background of Structural Element Condition Ratings

Structural element condition ratings provide a detailed condition evaluation of the bridge by dividing thebridge into separate elements, which are then rated individually based upon the severity and extent of anydeterioration. This rating system was developed by the American Association of State Highway andTransportation Officials (AASHTO), and is outlined in the “AASHTO Guide for Commonly Recognized(CoRe) Structural Elements”.

Structural element condition ratings provide input data for a Bridge Management System (BMS) whichallows computer projections of deterioration rates, providing cost-effective options for bridgemaintenance, rehabilitation, or replacement. Bridge Management Systems are intended to be a source ofinformation (and qualitative backing) for engineers and managers responsible for long-range bridgeimprovement programs. MnDOT adopted an element based bridge inspection format in 1994 to complywith the 1991 Inter-Modal Surface Transportation Efficiency Act (ISTEA), which mandated that all statesdevelop and implement a Bridge Management System (BMS) by October of 1998.

An “element” refers to structural members (beams, pier columns, decks, etc.), or any other components(railings, expansion joints, approach panels, etc.) commonly found on a bridge. This manual includesapproximately 150 elements - this includes the AASHTO CoRe (commonly recognized) elements, as wellas elements added by MnDOT to better represent the bridge types and components found in Minnesota.

3.1.2 Structural Element Types

Structural elements are divided into five groups, depending upon their structural function…

Deck Elements (decks, slabs, railings, and expansion joints) Superstructure Elements (girders, beams, arches, trusses, and bearings) Substructure Elements (abutments, wingwalls, pilings, columns, pier caps and pier walls) Culvert Elements (culverts and culvert headwalls/wingwalls) Miscellaneous Elements (“smart flags” and miscellaneous bridge elements)

Structural elements are also divided into six material groups - the condition rating descriptions (and ratingscales) will vary according to the material type.

Painted Steel Unpainted Weathering Steel Reinforced Concrete Pre-stressed (or Post-Tensioned) Concrete Timber Masonry, Other Material, or Combination of Materials

Note: “Smart Flag” elements identify conditions or problems present on a bridge that are not adequatelyaddressed by the conventional structural elements. Some smart flags refer to specific problems that maywarrant special attention or follow-up action, while some smart flags provide detailed information aboutthe condition of specific bridge elements or materials.


3.1.3 Structural Element Quantities & Ratings

Structural element quantities may be expressed in two ways…

Linear Feet (LF) elements display the total length of the element present on the bridge. Forexample, on a 100 ft. long bridge with five beam lines, the beam quantity would be 500 LF.

Each (EA) elements display the total quantity of the element present on the bridge. For example,on a bridge with three piers (and three columns on each pier), the column quantity would be “9”.

Structural elements are rated on a scale of 1-3, 1-4, or 1-5 (depending upon the element type andmaterial). In all cases, condition state 1 is the best condition, with condition state 3, 4, or 5 being theworst condition (this is the reverse of the NBI condition ratings).

If the severity of deterioration varies within a particular element, it may be rated using more than onecondition state. For example, on a bridge with 500 LF of beams, 250 LF could be rated as condition state1, 150 LF could be rated as condition state 2, and 100 LF could be rated as condition state 3. Elementsexpressed as an “Each” (EA) quantity can also be rated using more than one condition state (but only ifthe total quantity is greater than one). For example, on a bridge with 9 columns, five could be rated ascondition state 1, three could be rated as condition state 2, and one could be rated as condition state 3.Note: while deck elements are displayed as a “SF” quantity, the entire quantity must be rated as onecondition state.

3.1.4 Structural Element Display (Bridge Inspection Reports)

Only the structural elements that have been entered for a bridge will be displayed on the MnDOT BridgeInspection Report. The display order is determined by the element structural type - deck elements will bedisplayed first, followed by superstructure elements, substructure elements, culvert elements and thenmiscellaneous elements. The element condition ratings for the current inspection (as well as the previousinspection) will be displayed on the inspection report (in “LF” or “Each quantity). Inspection notespertaining to each element are displayed directly below each element.

3.1.5 Structure Units

Large or complex bridges that incorporate more than one structure type can be divided into structure units(a structure unit may consist of an individual span or a group of spans with the same structure type). Note:if you wish to divide a bridge into structure units, please contact the MnDOT Bridge Data Office.


3.2 MnDOT Structural Element List

This element list is arranged in groups based upon the element type and/or material. Each structuralelement is assigned a number - AASHTO CoRe deck elements are numbered between 1 and 99,AASHTO CoRe superstructure elements are numbered between 100 and 199, and AASHTO CoResubstructure elements are numbered between 200 and 299. Smart Flag elements and elements added byMnDOT are numbered between 300 and 999 (elements higher than 370 were added by MnDOT).

MnDOT Structural Element List# Element Description Element Type Units Scale Page

Concrete Decks12 Top of Concrete Deck with Uncoated Rebar (No Overlay) Deck Each 1-5 3213 Bituminous Overlay (Concrete Deck) Deck Each 1-5 3314 Bituminous Overlay with Membrane (Concrete Deck) Deck Each 1-5 3318 Latex, Epoxy, or Thin Overlay (Concrete Deck) Deck Each 1-5 3322 Low Slump Overlay (Concrete Deck with Uncoated Rebar) Deck Each 1-5 3226 Top of Concrete Deck with Epoxy Reinforcement (No Overlay) Deck Each 1-5 3227 Top of Concrete Deck with Cathodic Protection System Deck Each 1-5 32

377 Low Slump Overlay (Concrete Deck with Epoxy Rebar) Deck Each 1-5 32429 Top of Conc. Deck w/Epoxy Rebar top mat only (No Overlay) Deck Each 1-5 32430 Low Slump Overlay (Conc. Deck w/Epoxy Rebar top mat only) Deck Each 1-5 32

Concrete Slabs38 Top of Concrete Slab with Uncoated Rebar (No Overlay) Deck Each 1-5 3239 Bituminous Overlay (Concrete Slab) Deck Each 1-5 3340 Bituminous Overlay with Membrane (Concrete Slab) Deck Each 1-5 3344 Latex, Epoxy, or Thin Overlay (Concrete Slab) Deck Each 1-5 3348 Low Slump Overlay (Concrete Slab with Uncoated Rebar) Deck Each 1-5 3252 Top of Concrete Slab with Epoxy Reinforcement (No Overlay) Deck Each 1-5 3253 Top of Concrete Slab with Cathodic Protection System Deck Each 1-5 32

378 Low Slump Overlay (Concrete Slab with Epoxy Rebar) Deck Each 1-5 32405 Top of CIP Concrete Voided Slab (No Overlay) Deck Each 1-5 32406 Low Slump Overlay (CIP Concrete Voided Slab) Deck Each 1-5 32431 Top of Conc. Slab w/Epoxy Rebar top mat only (No Overlay) Deck Each 1-5 32432 Low Slump Overlay (Conc. Slab w/Epoxy Rebar top mat only) Deck Each 1-5 32

Timber Decks & Slabs31 Timber Deck (No Overlay) Deck Each 1-4 3432 Timber Deck with Bituminous (AC) Overlay Deck Each 1-4 3454 Timber Slab (No Overlay) Deck Each 1-4 3455 Timber Slab with Bituminous (AC) Overlay Deck Each 1-4 34

Other Deck Types28 Steel Grid Deck - Open Deck Each 1-5 3529 Steel Grid Deck - Concrete Filled Deck Each 1-5 3530 Corrugated, Orthotropic, Exodermic, or Other Deck Deck Each 1-5 35

401 Steel Ballast Plate Deck (Railroad Bridges) Deck Each 1-5 36

Deck Joints300 Strip Seal Deck Joint Deck LF 1-3 37301 Poured Deck Joint Deck LF 1-3 37302 Compression Seal Deck Joint Deck LF 1-3 38303 Assembly Deck Joint (with or without seal) Deck LF 1-3 38304 Open Deck Joint Deck LF 1-3 39410 Modular Deck Joint Deck LF 1-3 39411 Finger Deck Joint Deck LF 1-3 40412 Approach Relief Joint Deck LF 1-3 40



Roadway Approaches320 Concrete Approach Slab (Bituminous Wearing Surface) Deck Each 1-4 41321 Concrete Approach Slab (Concrete Wearing Surface) Deck Each 1-4 41407 Bituminous Approach Roadway Deck Each 1-4 41408 Gravel Approach Roadway Deck Each 1-4 41

Bridge Railings330 Metal Bridge Railing (Uncoated or Unpainted) Deck LF 1-4 42331 Reinforced Concrete Bridge Railing Deck LF 1-4 42332 Timber Bridge Railing Deck LF 1-3 42333 Masonry, Other, or Combination Material Bridge Railing Deck LF 1-3 43334 Metal Bridge Railing (Coated or Painted) Deck LF 1-5 43409 Chain Link Fence Deck LF 1-5 43

Painted Steel Elements102 Painted Steel Box Girder Superstructure LF 1-5 44107 Painted Steel Girder or Beam Superstructure LF 1-5 44113 Painted Steel Stringer Superstructure LF 1-5 44121 Painted Steel Through Truss - Bottom Chord Superstructure LF 1-5 44126 Painted Steel Through Truss - Upper Members Superstructure LF 1-5 44131 Painted Steel Deck Truss Superstructure LF 1-5 44141 Painted Steel Arch Superstructure LF 1-5 44152 Painted Steel Floorbeam Superstructure LF 1-5 44202 Painted Steel Column Substructure Each 1-5 44231 Painted Steel Pier Cap/Bearing Cap Substructure LF 1-5 44384 Painted Steel Arch Spandrel Column Superstructure Each 1-5 44419 Painted Steel Piling Substructure Each 1-5 44422 Painted Steel Beam Ends Superstructure Each 1-5 45423 Painted Steel Gusset Plate Truss Connection Superstructure Each 1-5 44425 Painted Steel Pinned Truss Connection Superstructure Each 1-5 44427 Painted Steel Pier Cap (Superstructure) Superstructure LF 1-5 44

Weathering Steel Elements101 Weathering Steel Box Girder Superstructure LF 1-4 46106 Weathering Steel Girder or Beam Superstructure LF 1-4 46112 Weathering Steel Stringer Superstructure LF 1-4 46120 Weathering Steel Through Truss - Bottom Chord Superstructure LF 1-4 46125 Weathering Steel Through Truss - Upper Members Superstructure LF 1-4 46130 Weathering Steel Deck Truss Superstructure LF 1-4 46140 Weathering Steel Arch Superstructure LF 1-4 46151 Weathering Steel Floorbeam Superstructure LF 1-4 46201 Weathering Steel Column Substructure Each 1-4 46225 Weathering Steel Piling Substructure Each 1-4 46230 Weathering Steel Pier Cap/Bearing Cap Substructure LF 1-4 46413 Weathering Steel Arch Spandrel Column Superstructure Each 1-4 46424 Weathering Steel Gusset Plate Truss Connection Superstructure Each 1-4 46426 Weathering Steel Pinned Truss Connection Superstructure Each 1-4 46428 Weathering Steel Pier Cap (Superstructure) Superstructure LF 1-4 46

Reinforced Concrete Elements105 Reinforced Concrete Box Girder Superstructure LF 1-4 47110 Reinforced Concrete Girder or Beam Superstructure LF 1-4 47116 Reinforced Concrete Stringer Superstructure LF 1-4 47144 Reinforced Concrete Arch Superstructure LF 1-4 47155 Reinforced Concrete Floorbeam Superstructure LF 1-4 47205 Reinforced Concrete Column Substructure Each 1-4 47210 Reinforced Concrete Pier Wall Substructure LF 1-4 47



215 Reinforced Concrete Abutment Substructure LF 1-4 47220 Reinforced Concrete Footing Substructure Each 1-4 47227 Reinforced Concrete Piling Substructure Each 1-4 47234 Reinforced Concrete Pier Cap/Bearing Cap Substructure LF 1-4 47375 Precast Concrete Channels Superstructure LF 1-4 47385 Reinforced Concrete Arch Spandrel Column Superstructure Each 1-4 47387 Reinforced Concrete Wingwall Substructure Each 1-4 47414 Reinforced Concrete Arch Spandrel Wall Superstructure LF 1-4 47

Prestressed or Post-Tensioned Concrete Elements104 Prestressed Concrete Box Girder Superstructure LF 1-4 48109 Prestressed Concrete Girder or Beam Superstructure LF 1-4 48115 Prestressed Concrete Stringer Superstructure LF 1-4 48143 Prestressed Concrete Arch Superstructure LF 1-4 48154 Prestressed Concrete Floorbeam Substructure LF 1-4 48204 Prestressed Concrete Column Substructure Each 1-4 48226 Prestressed Concrete Piling Substructure Each 1-4 48233 Prestressed Concrete Pier Cap/Bearing Cap Substructure LF 1-4 48374 Prestressed Concrete Double, Quad, Bulb, or Inverted Tees Superstructure LF 1-4 48402 Prestressed Concrete Voided Slab Panels Superstructure LF 1-4 48

Timber Elements111 Timber Girder or Beam Superstructure LF 1-4 49117 Timber Stringer Superstructure LF 1-4 49135 Timber Arch or Truss Superstructure LF 1-4 49156 Timber Floorbeam Superstructure LF 1-4 49206 Timber Column Substructure Each 1-4 49216 Timber Abutment Substructure LF 1-4 49228 Timber Piling Substructure Each 1-4 49235 Timber Pier Cap/Bearing Cap Substructure LF 1-4 49386 Timber Wingwall Substructure Each 1-4 49415 Timber Transverse Stiffener Beam (Timber Slabs) Deck LF 1-4 49

Masonry, Other, or Combination Material Elements145 Masonry, Other, or Combination Material Arch Superstructure LF 1-4 50211 Masonry, Other, or Combination Material Pier Wall Substructure LF 1-4 50217 Masonry, Other, or Combination Material Abutment Substructure LF 1-4 50416 Masonry, Other, or Combination Material Pier Cap/Bearing Cap Substructure LF 1-4 50417 Masonry, Other, or Combination Material Column Substructure Each 1-4 50418 Masonry, Other, or Combination Material Wingwall Substructure Each 1-4 50420 Masonry, Other, or Combination Material Arch Spandrel Wall Superstructure LF 1-4 50

Other Structural Elements310 Elastomeric (Expansion) Bearing Superstructure Each 1-3 54311 Expansion Bearing Superstructure Each 1-3 55312 Enclosed/Concealed Bearing Superstructure Each 1-3 57313 Fixed Bearing Superstructure Each 1-3 57314 Pot Bearing Superstructure Each 1-3 58315 Disk Bearing Superstructure Each 1-3 58161 Pin & Hanger (or Hinge Pin) Assembly - Painted Superstructure Each 1-5 60373 Steel Hinge Assembly Superstructure Each 1-5 63379 Concrete Hinge Assembly Superstructure Each 1-4 64146 Steel Cable (Bare) Superstructure Each 1-4 65147 Steel Cable (Coated or Encased) Superstructure Each 1-5 65380 Secondary Structural Elements Superstructure Each 1-4 66382 Cast-In-Place (CIP) Piling Substructure Each 1-4 67381 Tunnel Superstructure LF 1-4 67



Culvert Elements240 Steel Culvert Culvert LF 1-4 71241 Reinforced Concrete Culvert Culvert LF 1-4 71242 Timber Culvert Culvert LF 1-4 72243 Masonry, Other, or Combination Material Culvert Culvert LF 1-4 72388 Culvert Wingwall, Headwall, or Other End Treatment Culvert Each 1-4 73421 Culvert Footing Culvert LF 1-4 73

Smart Flags356 Fatigue Cracking Smart Flag Superstructure Each 1-3 74357 Pack Rust Smart Flag Superstructure Each 1-4 75358 Concrete Deck Cracking Smart Flag Deck Each 1-4 75359 Underside of Concrete Deck Smart Flag Deck Each 1-5 76360 Substructure Settlement & Movement Smart Flag Substructure Each 1-3 76361 Scour Smart Flag Substructure Each 1-3 77362 Traffic Impact Smart Flag Superstructure Each 1-3 77363 Section Loss Smart Flag Superstructure Each 1-4 78964 Critical Finding Smart Flag Miscellaneous Each 1-2 78965 Concrete Shear Cracking Smart Flag Superstructure Each 1-4 79966 Fracture Critical Smart Flag Superstructure Each 1-3 79967 Gusset Plate Distortion Smart Flag Superstructure Each 1-4 80

Other Items981 Signing Miscellaneous Each 1-3 81982 Guardrail Deck Each 1-3 81983 Plowstraps Deck Each 1-3 81984 Deck & Approach Drainage Deck Each 1-3 82985 Slopes & Slope Protection Substructure Each 1-3 82986 Curb & Sidewalk Deck Each 1-3 82987 Roadway over Culvert Culvert Each 1-3 83988 Miscellaneous Items Miscellaneous Each 1-3 83


3.3 Deck & Slab Structural Elements

This section includes structural element rating descriptions for decks, slabs, deck joints, bridgeapproaches, and bridge railings.

3.3.1 Rating Procedures for Concrete Decks & Slabs

Concrete deck (and slab) elements are selected based upon the wearing surface material (low slumpconcrete, bituminous, etc.), as well as the type of corrosion prevention system (such as epoxy coatedreinforcement). In this manual, the condition rating descriptions for concrete deck and slab elements aredivided into four groups…

Section 3.3.2: Concrete decks & slabs without overlays Section 3.3.3: Concrete decks & slabs with low slump overlays Section 3.3.4: Concrete decks & slabs with latex or epoxy overlays Section 3.3.5: Concrete decks & slabs with bituminous overlays

All concrete deck and slab elements are rated on a scale of 1 to 5 (with 1 being “very good” condition and5 being the worst condition). Although the quantity is displayed in square ft., the entire quantity must berated as a single condition state. Note: The condition ratings for concrete decks & slabs are based solelyupon the condition of the wearing surface! Smart Flag element #359 (Underside of Deck/Slab) must berated to describe the condition of the supporting concrete deck (or slab)!

The condition ratings for concrete deck elements are based upon the percentage of unsound wearingsurface (see Section 2.2.8). This quantity may be estimated from field observations, or calculated from adeck condition survey (such as chaining or ground penetrating radar). “Unsound” wearing surfaceincludes areas with delamination, spalling, potholes, severe scale, or other significant deterioration.Temporary patches (such as a bituminous fill patch on a concrete wearing surface) should be consideredto be “unsound”. Higher quality (long-term) patches should not necessarily be considered “unsound” untilthese repaired areas have begun to deteriorate.

If the deck has a concrete wearing surface, Smart Flag element #358 (Deck Cracking) must also be rated.This smart flag is not required for decks with bituminous overlays (or if the wearing surface is covered ingravel).

The wearing surface type, depth, and year of installation should be displayed on the MnDOT StructureInventory Report - if not, this information should be noted on the inspection report. The inspector shouldnote any changes in the type or depth of the wearing surface - a new overlay may require a new deckelement, and any increase in the wearing surface depth will require a new load rating.

While the presence of gravel is not a consideration when selecting deck elements, the gravel depth shouldbe noted on the inspection report (excessive gravel may reduce the load rating). Concrete decks coveredin gravel will typically be rated as condition “1” (as the top of the deck is not visible for inspection).

The deck protection system (and year of installation) should be displayed on the MnDOT StructureInventory Report. Virtually all bridge decks constructed in Minnesota since 1980 have epoxy coatedreinforcement - however, decks constructed in the early 1980’s often had epoxy coated reinforcement onthe top mat only (uncoated reinforcement was used on the lower mat). These bridge decks tend to haveincreased deterioration (rust staining and delamination) on the underside. Decks with bituminous overlaysoften have a waterproof membrane to protect the underlying deck - the plans may have to be reviewed todetermine the proper deck element.


3.3.2 Concrete Decks & Slabs (Without Overlays)

These elements describe the wearing surface condition on concrete decks (or slabs) that do not have anoverlay. This can include concrete decks (or slabs) covered with gravel. Note: Smart Flag elements #359(Underside of Concrete Deck) and #358 (Deck Cracking) should also be rated.

#12: Top of Concrete Deck with Uncoated Rebar (No Overlay)#26: Top of Concrete Deck with Epoxy Rebar (No Overlay)#27: Top of Concrete Deck (with Cathodic Protection System)#38: Top of Concrete Slab with Uncoated Rebar (No Overlay)#52: Top of Concrete Slab Epoxy Rebar (No Overlay)#53: Top of Concrete Slab (with Cathodic Protection System)#405: Top of Cast-in-Place Concrete Voided Slab (No Overlay)#429: Top of Concrete Deck with Epoxy Rebar on the Top Mat Only (No Overlay)#431: Top of Concrete Slab with Epoxy Rebar on the Top Mat Only (No Overlay)

Condition State 1: Top (wearing) surface of deck has no spalls, delaminations, or temporary patches.

Condition State 2: The combined area of unsound wearing surface (spalls, delaminations, temporarypatches, etc.) is 2% or less of the total deck area.

Condition State 3: The combined area of unsound wearing surface (spalls, delaminations, temporarypatches, etc.) is more than 2% but not more than 10% of the total deck area.


Condition State 5: The combined area of unsound wearing surface (spalls, delaminations, temporarypatches, etc.) is more than 25% of the total deck area.

3.3.3 Concrete Decks & Slabs (Low Slump Overlays)

These elements describe the condition of low slump concrete overlays on concrete decks (or slabs). Note:Smart Flag element #359 (Underside of Concrete Deck) must be also be rated to describe the condition ofthe supporting concrete deck (or slab)! Smart Flag element #358 (Deck Cracking) must also be rated.

#22: Low Slump Overlay (Concrete Deck with Uncoated Rebar)#48: Low Slump Overlay (Concrete Slab with Uncoated Rebar)#377: Low Slump Overlay (Concrete Deck with Epoxy Rebar)#378: Low Slump Overlay (Concrete Slab with Epoxy Rebar)#406: Low Slump Overlay (Cast-in-Place Concrete Voided Slab)#430: Low Slump Overlay (Concrete Deck with Epoxy Rebar on the Top Mat Only)#432: Low Slump Overlay (Concrete Slab with Epoxy Rebar on the Top Mat Only)

Condition State 1: Low slump overlay has no spalls, delaminations, or temporary patches.




Condition State 5: The combined area of distressed or unsound wearing surface (spalls, delaminations,patches, etc.) is more than 25% of the total deck area.


3.3.4 Concrete Decks & Slabs (Latex or Epoxy Overlays)

These elements describe the condition of latex, epoxy, or thin (less than 1”) overlays on concrete decks(or slabs). Epoxy & Latex overlays were used sparingly in Minnesota in the 1970’s & 1980’s, but are nowseldom used. Note: Smart Flag element #359 (Underside of Deck or Slab) must be also be rated todescribe the condition of the supporting concrete deck (or slab)!

#18: Latex, Epoxy, or Thin Overlay (Concrete Deck)#44: Latex, Epoxy, or Thin Overlay (Concrete Slab)

Condition State 1: Latex/Epoxy overlay has no spalls, delaminations, or patches.




Condition State 5: The combined area of unsound wearing surface (spalls, delaminations, temporarypatches, etc.) is more than 25% of the total deck area.

3.3.5 Concrete Decks & Slabs (Bituminous Overlays)

These elements describe the condition of bituminous overlays on concrete decks (or slabs). The plansshould be referenced to determine if there is a waterproof membrane below the overlay (the presence ofepoxy-coated reinforcement is not a consideration with these elements). Note: Smart Flag element #359(Underside of Deck or Slab) must be also be rated to describe the condition of the supporting concretedeck (or slab)! Smart Flag Element #358 (Deck Cracking) should not be used for bituminous overlays.

#13: Bituminous Overlay (Concrete Deck)#14: Bituminous Overlay with Membrane (Concrete Deck)#39: Bituminous Overlay (Concrete Slab)#40: Bituminous Overlay with Membrane (Concrete Slab)

Condition State 1: Bituminous overlay has no potholes, spalls, or temporary patches.

Condition State 2: The combined area of unsound wearing surface (potholes, spalls, temporary patches,etc.) is 2% or less of the total deck area.

Condition State 3: The combined area of unsound wearing surface (potholes, spalls, temporary patches,etc.) is more than 2% but not more than 10% of the total deck area.

Condition State 4: The combined area of unsound wearing surface (potholes, spalls, temporary patches,etc.) is more than 10% but not more than 25% of the total deck area.

Condition State 5: The combined area of unsound wearing surface (potholes, spalls, temporary patches,etc.) is more than 25% of the total deck area.


3.3.6 Timber Decks & Slabs

These elements apply to timber decks or slabs - this includes timber, bituminous or gravel wearingsurfaces. This includes timber plank decks, glue-lam deck panels, and nail laminated timber decks orslabs. All of these elements are an “each” item (the quantity will be displayed as the deck area in squareft.) - they are rated on a scale of 1-4 (the entire deck/slab area must be rated under a single conditionstate).

Element #31: Timber Deck (No Overlay) Element #32: Timber Deck with Bituminous (AC) Overlay Element #54: Timber Slab (No Overlay) Element #55: Timber Slab with Bituminous (AC) Overlay

Timber plank decks are comprised of transverse timber planks (with the wide dimension in the horizontalplane). Timber plank decks often have longitudinal planks (“runners”) under each wheel track.

Nailed laminated timber decks consist of transverse timbers (with the wide dimension in the verticalposition) that are nailed to the adjacent timbers. Nailed laminated decks often have a bituminous overlay.

Nail laminated timber slabs are similar to nail laminated decks, except the timbers are longitudinal, andserve as the primary superstructure element (the timbers are larger than those on a nail laminated deck).Timber slabs often have a bituminous wearing surface. Note: timber slabs often have a transversestiffener beam running below the slab near the center of the span - these beams can be rated usingelement #415.

Glulam timber deck panels are typically 4 ft. wide and are typically installed transversely to the directionof traffic (these are often used for temporary bridges, and frequently have a bituminous overlay).

Condition State 1: Timber deck/slab has little or no deterioration. Timber components may have minorweathering or splitting. All deck/slab components are properly orientated and solidly connected. Runningplanks (if present) are in good condition and soundly attached. Bituminous overlay (if present) is in goodcondition (no potholes).

Condition State 2: Timber deck/slab has minor to moderate deterioration. Timber components may havemoderate weathering or splitting - there may be minor decay, crushing, or sagging. Deck/slab componentsmay be slightly loose or misaligned. Running planks may be worn or slightly loose. Bituminous overlaymay have moderate cracking - there may be some potholes.

Condition State 3: Timber deck/slab has extensive deterioration - repairs may be recommended, but theload-carrying capacity of the deck has not been significantly reduced. Timber components may haveextensive weathering or splitting - there may be decay, crushing, or sagging. Deck/slab components maybe missing, loose, or misaligned. Running planks may be misaligned (some sections may be missing).Bituminous overlay may have extensive cracking or potholes.

Condition State 4: Timber deck/slab has severe or critical deterioration. Full-depth failures may bepresent - immediate repairs may be necessary. Timber components may have severe decay, crushing, orsagging. Wearing surface may have failed.


3.3.7 Other Deck Types

Element #28: Steel Grid Deck - Open Element #29: Steel Grid Deck - Concrete Filled

Element #28 applies to open grid steel deck, Element #29 refers to steel grid decks that have been fully orpartially filled with concrete. Steel grid panels may be welded, riveted, or bolted - the top edges are oftenserrated to improve traction. Both of these elements are an “each” item (the quantity will be displayed asthe deck area in square ft.) - they are rated on a scale of 1-5 (the entire deck area must be rated under asingle condition state). Note: The rating should take into consideration any deck support components thatare not addressed by other structural elements.

Condition State 1: Steel grid deck has little or no deterioration. The paint or galvanizing system (ifpresent) remains sound - there is no notable corrosion. All deck supports and connections (welds, rivets,bolts, etc.) are in good condition. Concrete filler (if any) is in good condition.

Condition State 2: Steel grid deck has minor deterioration. Paint or galvanizing system (if present) mayhave some failure - surface corrosion may be present. Deck supports and connections may have minordeterioration, but remain sound. Concrete filler (if any) may have minor deterioration, but remains intact.

Condition State 3: Steel grid deck has moderate deterioration. Paint or galvanizing system (if present)may have moderate failure - surface corrosion may be prevalent, but any section loss is incidental. Decksupports and connections may have moderate deterioration or isolated failure (cracked welds or brokenrivets), but the grid panels remain secure and in proper alignment. Concrete filler (if any) may havemoderate deterioration - the concrete may have broken out in some locations.

Condition State 4: Steel grid deck has extensive deterioration. Paint or galvanizing system (if present)may have complete failure. There may be extensive surface corrosion or measurable section loss. Failureof support components and connections may have resulted in some grid panels coming slightly loose orout alignment. Concrete filler (if any) may have extensive deterioration - the concrete may have brokenout in numerous locations.

Condition State 5: Steel grid deck has severe or deterioration - immediate repairs may be required. Thesteel grid panels may have severe section loss (areas may have rusted through). Failure of supportcomponents and connections may have resulted in some grid panels coming severely loose or out ofalignment. Most of the concrete filler may be missing.

Element #30: Corrugated, Orthotropic, Exodermic, or Other Deck

This element applies corrugated decks, orthotropic decks, or any deck type not adequately described bythe other deck elements. This element is an “each” item (the quantity will be displayed as the deck area insquare ft.). This element is rated on a scale of 1-5 (the entire deck area must be rated under a singlecondition state).

Corrugated decks are typically comprised of corrugated steel forms (with concrete or bituminous fill), inwhich the steel forms provide the primary structural support.

An Orthotropic deck typically consists of a steel plate that has been stiffened by closely spaced ribs. Anorthotropic deck acts integrally with the superstructure.

An Exodermic deck is a recently developed modular design that combines a steel grid with a reinforcedconcrete deck (advantages include light weight and rapid construction). This design has only been used ona limited basis in Minnesota.


Condition State 1: Deck has little or no deterioration. Paint or galvanizing system (if present) remainssound - there is no notable corrosion. The wearing surface (or filler material) is sound, with no notabledeterioration.

Condition State 2: Deck has minor deterioration. Paint or galvanizing system (if present) may have somefailure - surface corrosion may be present. Wearing surface (or filler material) may have minordeterioration (cracking, spalling, or potholes).

Condition State 3: Deck has moderate deterioration. Paint or galvanizing system (if present) may havemoderate failure - surface corrosion may be prevalent, but any section loss is incidental. Wearing surface(or filler material) may have moderate deterioration (cracking, spalling, or potholes) - but the underlyingdeck forms are not exposed.

Condition State 4: Deck has extensive deterioration. Paint or galvanizing system (if present) may havecomplete failure. There may be extensive surface corrosion or measurable section loss. Wearing surface(or filler material) may have extensive deterioration - the underlying deck may be exposed.

Condition State 5: Deck has severe deterioration - immediate repairs may be required. Steel deckcomponents may have severe section loss (areas may have rusted through). Wearing surface (or fillermaterial) may have severe deterioration - a significant portion of the underlying decking may be exposed.

Element #401: Steel Ballast Plate Deck (Railroad Bridges)

This element applies to steel ballast plate decks (commonly used on railroad bridges). These decks consistof steel plates attached directly to the superstructure (they are often connected with clips that allow thedeck to expand independently from the superstructure). The steel ballast plate is typically covered with awaterproof membrane and rock ballast (the railroad ties are placed on the ballast). This element is an“each” item (the quantity will be displayed as the deck area in square ft.). This element is rated on a scaleof 1-5 (the entire deck area must be rated under a single condition state). Note: The inspector should noteif the railroad tracks are active, abandoned, or removed.

Condition State 1: Steel ballast plate deck has little or no deterioration. Paint system (if present) remainssound - there is no notable corrosion. There is no deck leakage. All ballast clips (or other deckconnections) are secure. Rock ballast and wearing surface (if present) have no notable deterioration.

Condition State 2: Steel ballast plate deck has minor deterioration. Paint system (if present) may havesome failure - surface corrosion may be present. There may be minor deck leakage. A small number ofballast clips (or other connections) may be loose or missing. Rock ballast and wearing surface (if present)may have minor deterioration.

Condition State 3: Steel ballast plate deck has moderate deterioration. Paint system (if present) may havemoderate failure - surface corrosion may be prevalent, but any section loss is incidental. There may bemoderate deck leakage. Several ballast clips (or other connections) may be loose or missing. Rock ballastand wearing surface (if present) may have moderate deterioration.

Condition State 4: Steel ballast plate deck has extensive deterioration. Paint system (if present) may havecomplete failure. There may be extensive surface corrosion or measurable section loss. There may beextensive deck leakage. A significant number of ballast clips (or other connections) may be loose ormissing. Rock ballast and wearing surface (if present) may have extensive deterioration.

Condition State 5: Steel ballast plate railroad deck has severe deterioration - immediate repairs may berequired. Steel deck components may have severe section loss (areas may have rusted through), or may beloose or out of alignment.


3.3.8 Deck Joints

Deck joint elements are rated on a scale of 1-3 - condition “3” typically indicates that joint repair orreplacement is required. The quantity is listed as linear feet, measured along the full length of theexpansion joint (this includes the roadway, as well as joints through railings, medians, and sidewalks).

Deck joints should be inspected for leakage, as well as for proper function. Deck joints should beexamined for skew, offset, or any evidence that the joint is restricted or is beyond the limits of expansion.Note: deck expansion joints that are closed tightly, offset vertically or horizontally, or have large gapsmay indicate severe structural problems (such as substructure movement).

Element #300: Strip Seal Deck Joint

This element applies to deck joints that utilize a “V” shaped neoprene gland, typically held in place by asteel extrusion.

Strip seal joints came into use inMinnesota in 1974, and are now the

predominant type of bridge deckexpansion joint.

A cross-section plan diagram of typicalstrip seal deck joint is shown at left.

Condition State 1: Strip seal joint has little or no deterioration (no leakage). Gland is sound and securelyanchored. Joint anchorage and adjacent deck remain sound and intact. Joint is properly aligned andfunctioning as intended. Debris in the joint (if any) is not causing any problems.

Condition State 2: Strip seal joint has moderate deterioration - minor leakage may be evident. Glandmay be partially pulled out. Joint anchorage may be slightly damaged. Adjacent deck may have minorspalling. Joint may be slightly misaligned (skewed, offset, or near limits of expansion), but the functionhas not been significantly impaired. Debris in the joint may be causing problems.

Condition State 3: Strip seal joint has severe deterioration - there may be significant leakage. Gland maybe punctured, torn, or pulled loose. The joint anchorage may be damaged or deteriorated to the extent thatthe gland can no longer be properly anchored. Adjacent deck may have severe spalling. Joint may beseverely misaligned - the function may be significantly impaired.

Element #301: Poured Deck Joint

This element applies to deck joints filled with a poured or extruded sealant - this typically refers to saw &seal joints (above piers or along end blocks), but can also include bituminous plug joints or median joints.

Condition State 1: Poured joint has little or no deterioration (no leakage). Joint sealant is properlyadhered. Adjacent deck is sound and intact.

Condition State 2: Joint is leaking - poured sealant has adhesion failure or may be missing. Adjacentdeck may have minor cracking or spalling.

Condition State 3: Deck adjacent to poured joint has severe spalling - concrete repairs or jointreplacement may be necessary.


Element #302: Compression Seal Deck Joint

This element applies to deck joints consisting of a pre-formed elastic compression seal. Compressionseals may have a solid or hollow cross-section - the joint may or may not include steel protection angles.Note: this element should not be used for approach relief joints (use element #412 instead).

Compression seal deck joints are seldom used inbridge decks in Minnesota - they were phased out

in favor of strip seal joints around 1975.

A cross-section plan diagram of typicalcompression seal deck joint (with steel

protection angles) is shown at left.

Condition State 1: Compression joint has little or no deterioration (no leakage). Compression seal issound and securely anchored. Protection angles (if present) are in good condition. Adjacent deck remainssound and intact. Joint is properly aligned and functioning as intended. Debris in the joint (if any) is notcausing any problems.

Condition State 2: Compression joint has moderate deterioration (minor leakage may be evident).Compression seal may be slightly loose or out of position. Protection angles may have minor damage.Adjacent deck may have minor spalling. Joint may be slightly misaligned (skewed, offset, or near limitsof expansion), but the function has not been significantly impaired. Debris in the joint may be causingproblems.

Condition State 3: Compression joint has severe deterioration (there may be significant leakage).Compression seal may be punctured, torn, or out of position. Protection angles may have severe damage.Adjacent deck may have severe spalling. Joint may be severely misaligned - joint function may besignificantly impaired.

Element #303: Assembly Deck Joint (with or without seal)

This element applies to deck joints consisting of an assembly mechanism (with or without a seal). Thisincludes deck joints comprised of sliding steel plates, anchored rubber seals, or any joint that is notadequately described by the other deck joint elements.

Condition State 1: Assembly joint has little or no deterioration. If the joint is sealed, there is no leakage.All joint components are sound and securely anchored. Steel components have little or no corrosion.Adjacent deck remains sound and intact. Joint is properly aligned and functioning as intended. Debris inthe joint (if any) is not causing any problems.

Condition State 2: Assembly joint has moderate deterioration. If the joint is sealed, minor leakage maybe evident. Joint components may be loose. Steel components may have moderate corrosion and/orsection loss. Adjacent deck may have minor spalling. Joint may be slightly misaligned (skewed, offset, ornear limits of expansion), but the function has not been significantly impaired. Debris in the joint may becausing problems.

Condition State 3: Assembly joint has severe deterioration. Seals may have failed. Joint componentsmay be missing. Steel components may have severe section loss. Adjacent deck may have severe spalling.Joint may be severely misaligned - joint function may be significantly impaired.


Element #304: Open Deck Joint

This element applies to open deck joints (with or without steel protection angles).

Condition State 1: Open joint has little or no deterioration. Protection angles (if present) are sound andsecurely anchored. Adjacent deck is sound. Joint is properly aligned and functioning as intended.

Condition State 2: Open joint has moderate deterioration. Protection angles may have moderatecorrosion damage or may have started to loosen - some anchor bolts may be loose, broken or missing.Adjacent deck may have minor spalling. Joint may be slightly misaligned (skewed, offset, or near limitsof expansion), but the function not been significantly impaired.

Condition State 3: Open joint has severe deterioration. Protection angles may be severely damaged ormissing. Adjacent deck may have severe spalling. Joint may be severely misaligned - joint function maybe significantly impaired.

Element #410: Modular Deck Joint

This element applies to “Modular” deck joints. Modular deck joints are comprised of two or moreadjacent waterproof seals (“V” strip or compression seal). The seals are typically anchored by steelextrusions cast into the deck, and supported from below by small beams (which often have anindependent expansion bearing system). Modular joints typically incorporate equalizer springs and guidesystems to keep the seals equally spaced and properly aligned.

Condition State 1: Modular joint has little or no deterioration (no leakage). Seals are sound and securelyanchored. All joint components (extrusion/joint anchorage, support beams, equalizers, and guide systems)are sound and intact. Adjacent deck is sound. Joint is properly aligned and functioning as intended. Debrisin the joint (if any) is not causing any problems.

Condition State 2: Modular joint has moderate deterioration - minor leakage may be evident. Seals maybe partially pulled out, slightly loose or out of position. Joint equalizers (or guide system components)may be loose, damaged or missing. Joint support beams remain sound and intact. The joint anchoragemay be slightly damaged. Adjacent deck may have minor spalling. Joint may be slightly misaligned(skewed, offset, or near limits of expansion), but the function has not been significantly impaired. Debrisin the joint may be causing problems.

Condition State 3: Modular joint has severe deterioration - there may be significant leakage. Seals maybe punctured, torn, pulled loose, or out of position. Joint equalizer/guide system may be severelydeteriorated or no longer functioning. Support beams may be loose, jammed, or otherwise inoperative.Joint anchorage may be damaged or deteriorated to the extent that the gland can no longer be properlyattached. Adjacent deck may have severe spalling. Joint may be severely misaligned - joint function maybe significantly impaired.


Element #411: Finger Plate Deck Joint

This element applies to finger plate deck joints (two steel plates with interlocking “fingers”).

Condition State 1: Finger plate joint has little or no deterioration. Expansion plates are securely anchored(all fingers are intact). Adjacent deck is sound. Joint is properly aligned and functioning as intended.

Condition State 2: Finger plate joint has moderate deterioration. Some fingers may be broken off.Expansion plates may have started to loosen - some anchor bolts may be loose, broken or missing (weldsmay have broken). Adjacent deck may have minor spalling. Joint may be slightly misaligned (skewed,offset, or near limits of expansion), but the function has not been significantly impaired.

Condition State 3: Finger plate joint has severe deterioration. A significant number of fingers may bebroken off. Expansion plates may be loose or missing - a large number of anchor bolts may be loose,broken or missing. Adjacent deck may have severe spalling. Joint may be severely misaligned - jointfunction may be significantly impaired.

Element #412: Approach Relief Joint

This element applies to approach slab relief joints. They are used when a concrete approach slab meets anadjacent concrete roadway, and are designed to accommodate expansion of the roadway). A typical reliefjoint is 4” wide and consists of preformed polystyrene filler with a hot poured seal.

Condition State 1: Approach relief joint has little or no deterioration. Joint seal and filler remain intact.Joint has not closed significantly. The adjacent roadway and approach are in good condition.

Condition State 2: Approach relief joint has moderate deterioration. Joint seal and/or filler material maybe missing - the joint may be filled with debris. Joint may be partially closed, but can still accommodateadditional expansion. Adjacent roadway or approach may have minor spalling.

Condition State 3: Approach relief joint has severe deterioration - repair or replacement may be required.Joint may be closed (or nearly closed), with no room for additional expansion. Adjacent roadway orapproach may have severe spalling.


3.3.9 Roadway Approach Elements

These elements apply to approach slabs and the roadway approaches to the bridge. These elements areonly intended to rate the condition of the approach - geometric alignment issues should be addressedusing the Approach Roadway Alignment Appraisal Rating (FHWA Item #72 - see section 2.2.2). Theseelements are “each” items (rated on a scale of 1-4). The quantity will typically be “2” (one for each end ofthe bridge) - they can be rated under separate condition states. If the bridge has a divided median or ramp,the quantity can be increased to rate each panel separately.

Element #320: Concrete Approach Slab (Bituminous Wearing Surface) Element #321: Concrete Approach Slab (Concrete Wearing Surface) Element #407: Bituminous Approach Roadway Element #408: Gravel Approach Roadway

Note: an “approach slab” is a short concrete paving segment between the end of the bridge and theapproach roadway (usually supported by the abutment parapet at the bridge end, and a concrete sill atthe roadway end). If approach slabs are not present, the “approach roadway” elements can be used (thistypically includes the approach roadway extending approximately 20 ft. from the end of the bridge).

Condition State 1: Approach has little or no deterioration. There is no settlement or undermining - theride transitions smoothly on/off the bridge deck. Concrete approaches may have minor cracking or wear -there are no delaminations or spalls. Bituminous approaches are smooth and even - there are no potholes.Gravel approaches are evenly graded.

Condition State 2: Approach has minor to moderate deterioration. There may be slight settlement orundermining, but traffic impact on the bridge has not been significantly increased. Concrete approachesmay have moderate cracking, scaling, or wear - there may be minor delamination or spalling. Bituminousapproaches may have moderate cracking, or may be slightly uneven - potholes may be present. Gravelapproaches may be moderately rutted or eroded.

Condition State 3: Approach has extensive deterioration - repairs may be required. Settlement orundermining may have significantly increased traffic impact on the bridge. Concrete approaches mayhave extensive scaling or cracking (cracking may extend through the underlying slab) - there may besignificant delamination or spalling. Bituminous approaches may have extensive cracking or potholes - ormay be uneven. Gravel approaches may have extensive rutting or erosion.

Condition State 4: Approach has severe or critical deterioration - immediate repairs may be required.Settlement or undermining may have severely increased traffic impact on the bridge. Deterioration of thewearing surface may be severe enough to present a traffic hazard.


3.3.10 Bridge Railing Elements

Select the railing element that best describes the railing present on the bridge (some bridges have morethan one railing type). Railing elements are “linear feet” quantities (the rating scale varies). The quantityis measured along the length of the railing, and can include railing on the wingwalls or approaches.

Element #330: Metal Bridge Railing (Uncoated or Unpainted) - this element applies to metalrailings that are not (and have never been) coated or painted.

Condition State 1: Uncoated metal railing has little or no deterioration. There may be minor surfacecorrosion, but there is no section loss. Railing may have minor impact damage.

Condition State 2: Uncoated metal railing has minor to moderate deterioration or impact damage. Theremay be surface corrosion (minor section loss). Components may be slightly bent or misaligned.

Condition State 3: Uncoated metal railing has extensive deterioration or impact damage. There may beextensive surface corrosion or section loss. Connections or anchorages may be slightly loose -components may be bent or misaligned.

Condition State 4: Uncoated metal railing has severe deterioration or impact damage - immediate repairsmay be required. There may be advanced corrosion or significant section loss. Connections or anchoragesmay have failed - components may be severed, torn loose, or missing.

Element #331: Reinforced Concrete Bridge Railing - this element applies to reinforced concreterailings (of any type or shape).

Condition State 1: Concrete railing has little or no deterioration. There may be minor cracking, scaling,pop-outs, leaching, or staining. There may be minor impact damage.

Condition State 2: Concrete railing has minor to moderate deterioration or impact damage. There may bemoderate cracking, scaling, leaching, or staining. There may be minor delamination or spalling.

Condition State 3: Concrete railing has extensive deterioration or impact damage. There may beextensive cracking, scaling, leaching, staining, delamination or spalling (with exposed rebar).

Condition State 4: Concrete railing has severe deterioration or impact damage - immediate repairs maybe required. There may be severe cracking, scaling, delamination or spalling (with exposed rebar).

Element #332: Timber Bridge Railing - this element applies to bridge railings comprised primarilyor entirely of timber.

Condition State 1: Timber railing has minor deterioration or impact damage. There may be minorweathering or cracking - but there is no decay or structural distress (crushing or sagging). All connectionsare sound and intact - all components are properly aligned.

Condition State 2: Timber railing has moderate deterioration or impact damage. There may be extensiveweathering or cracking - there may be some decay or structural distress (minor crushing or sagging).Connections may be slightly loose - components may be slightly misaligned.

Condition State 3: Timber railing has severe deterioration or impact damage - immediate repairs may berequired. There may be severe decay, crushing, or sagging (significant loss of cross-sectional area).Connections may have failed - components may be severely damaged or torn loose.


Element #333: Masonry, Other, or Combination Material Railing - this element applies torailings constructed of any combination of materials (concrete, steel, aluminum, timber, etc.), or anyrailing that cannot be adequately described by the other railing elements.

Condition State 1: Railing has minor deterioration or impact damage. Concrete may have minorcracking, scaling, or leaching. Steel may have minor surface corrosion - paint/coating system (if present)may have minor deterioration. Timber may have minor weathering or cracking. All connections andanchorages are sound and intact - all components are properly aligned.

Condition State 2: Railing has moderate deterioration or impact damage. Concrete may have moderatecracking, scaling, leaching, or spalling (exposed rebar). Steel may have moderate corrosion (some sectionloss) - paint/coating system may have extensive failure. Timber may have extensive weathering orcracking - there may be decay, crushing, or sagging. Connections or anchorages may be slightly loose -components may be slightly bent or misaligned.

Condition State 3: Railing has severe deterioration or impact damage - immediate repairs may berequired. Concrete may have severe cracking or spalling (exposed rebar). Steel may have severe corrosionor section loss. Timber may have severe decay, crushing, or sagging. Connections or anchorages mayhave failed - components may be severely bent, severed, fractured, or torn loose.

Element #334: Metal Bridge Railing (Coated or Painted) - this element applies to metal railingsthat have been painted, galvanized or otherwise coated.

Condition State 1: Coating metal railing has little or no deterioration (no corrosion or impact damage).

Condition State 2: Coating metal railing has minor deterioration. There may be minor surface corrosion(no section loss). Connections and anchorages are sound and intact.

Condition State 3: Coating metal railing has moderate deterioration. Surface corrosion may be prevalent(minor section loss). Connections or anchorages may be slightly loose - components may be slightly bentor misaligned.

Condition State 4: Coating metal railing has extensive deterioration. There may be extensive corrosion(measurable section loss). Connections or anchorages may be loose - components may be bent ormisaligned.

Condition State 5: Coated metal railing severe deterioration - immediate repairs may be required. Theremay be severe section loss. Connections or anchorages may have failed - components may be severed,torn loose, or missing.

Element #409: Chain Link Fence

Condition State 1: Chain link fence has little or no deterioration. Galvanizing or vinyl coating is sound.

Condition State 2: Chain link fence has minor deterioration. Coating may have minor failure - surfacerust may be present. Fence components are properly aligned (all connections are sound).

Condition State 3: Chain link fence has moderate deterioration. Coating may have moderate failure -surface rust may be prevalent. Components may be slightly bent or misaligned - connections may beslightly loose. Fabric may have snags or holes (areas may be slightly stretched or deformed).

Condition State 4: Chain link fence has extensive deterioration. Coating may have extensive failure -there may be section loss. Components may be bent or misaligned - connections may be loose. Fabricmay have numerous snags or holes (areas may be stretched or deformed).

Condition State 5: Chain link fence has severe deterioration - immediate repairs may be required.Components may be loose, missing, or severely bent.


3.4 Structural Elements (Grouped by Material Type)

This section includes rating descriptions for structural elements - mainly superstructure and substructure.The elements are grouped by material type (painted steel, unpainted weathering steel, reinforced concrete,pre-stressed concrete, timber, or masonry/other material).

3.4.1 Painted Steel Elements

These elements apply to structural steel members that have been painted (even if the paint system hascompletely failed).

Element #102: Painted Steel Box Girder (LF) Element #107: Painted Steel Girder or Beam (LF) Element #113: Painted Steel Stringer (LF) Element #121: Painted Steel Through Truss - Bottom Chord (LF) Element #126: Painted Steel Through Truss - Upper Members (LF) Element #131: Painted Steel Deck Truss (LF) Element #141: Painted Steel Arch (LF) Element #152: Painted Steel Floorbeam (LF) Element #202: Painted Steel Column (EA) Element #231: Painted Steel Pier Cap/Bearing Cap (LF) Element #384: Painted Steel Arch Spandrel Column (EA) Element #419: Painted Steel Piling (EA) Element #423: Painted Steel Gusset Plate Truss Connection (EA) Element #425: Painted Steel Pinned Truss Connection (EA) Element #427: Painted Steel Pier Cap - Superstructure (LF)

Condition State 1: Painted steel element has little or no deterioration. The paint system may have minorfading, salt film, or chalking, but there is no corrosion. There is no section loss (this includes repaintedareas).

Condition State 2: Painted steel element has minor deterioration. The paint system may have moderatedeterioration (chalking, peeling, blistering or other distress), but any exposed steel is limited. Surfacecorrosion (freckled rust) may be present, but there is no flaking rust. Repainted areas may have minorsection loss. All connections are sound - element is in proper position and alignment. Note: elements thathave been repaired or reinforced should generally not be rated above Condition 2.

Condition State 3: Painted steel element has moderate deterioration. The paint system may haveextensive deterioration. Surface corrosion (freckled rust) may be prevalent - there may be isolated flakingrust (with minor section loss). Repainted elements may have measurable section loss in non-criticallocations. Connections may have minor distress - element may be slightly out of alignment.

Condition State 4: Painted steel element has extensive deterioration - repairs may be required, but theload-carrying capacity of the element has not been significantly reduced. There may be severe corrosion,with extensive flaking rust. While there may be significant section loss, structural analysis is not yetrequired (section loss is less than 10% of the effective section). Connections may have started to comeloose - element may be out of proper position or alignment.

Condition State 5: Painted steel element has severe or critical deterioration. The load-carrying capacityhas been significantly reduced - structural analysis or immediate repairs may be required. Section lossmay exceed 10% of the effective section. There may be severe impact damage. Element may be severelydamaged, severed, or severely out of alignment. Connections may have failed.


3.4.1a Painted Steel Beam Ends (Element #422)

This element applies only to steel bridges on the Minnesota state trunk highway system - it is intended tocorrelate with MnDOT Technical Memorandum #06-10-B-01 “Bridge Preservation, Improvement, andReplacement Guidelines for Fiscal Year 2006 through 2008”. The “Guidelines for Bridge MaintenancePainting” are outlined on pages 38-40 of the memorandum, and are intended to preserve the structuralintegrity of steel bridges in the most cost effective and practical manner possible.

Element #422 tracks the paint condition of the steel superstructure located within 7 ft. on either side of atransverse deck joint. This includes (but is not limited to) steel girders, beams, trusses, arches,floorbeams, stringers etc. located below the deck (or above the deck within the “splash zone”). Note: therating of this element is in addition to any elements used to rate these superstructure members - therating of this element should not affect any existing element ratings (or element quantities).

This element is an “each” item - the quantity shall correspond with the number of transverse deck joints(typically expansion joints) on the portion of the bridge with a steel superstructure. The rating is basedupon a visual estimate of the percentage of “unsound” paint on the bridge superstructure within 7 ft. ofeach transverse deck joints. As the paint condition may vary from one joint to another, they may havedifferent condition ratings.

Condition State 1: The steel superstructure (within 7 ft. of the transverse deck joints) has no unsoundpaint.

Condition State 2: The paint on the steel superstructure (within 7 ft. of the transverse deck joints) isbetween 1% and 5% unsound.



Condition State 5: The paint on the steel superstructure (within 7 ft. of the transverse deck joints) ismore than 40% unsound.


3.4.2 Weathering Steel Elements

These elements apply only to structural members constructed of weathering steel (such as MnDOT Spec.#3309). This includes weathering steel members that have been left unpainted, as well as weathering steelmembers that have been partially or completely painted. Note: bridges constructed of unpaintedweathering steel are usually painted in “high corrosion areas” (on a steel beam bridge, this typicallyincludes the area within 7 ft. of a deck joint). Paint failure outside the “high corrosion” areas should beconsidered to be an aesthetic issue, and should not reduce the condition rating.

Element #101: Weathering Steel Box Girder (LF) Element #106: Weathering Steel Girder or Beam (LF) Element #112: Weathering Steel Stringer (LF) Element #120: Weathering Steel Through Truss - Bottom Chord (LF) Element #125: Weathering Steel Through Truss - Upper Members (LF) Element #130: Weathering Steel Deck Truss (LF) Element #140: Weathering Steel Arch (LF) Element #151: Weathering Steel Floorbeam (LF) Element #201: Weathering Steel Column (EA) Element #225: Weathering Steel Piling (EA) Element #230: Weathering Steel Pier Cap/Bearing Cap (LF) Element #413: Weathering Steel Arch Spandrel Column (EA) Element #424: Weathering Steel Gusset Plate Truss Connection (EA) Element #426: Weathering Steel Pinned Truss Connection (EA) Element #428: Weathering Steel Pier Cap - Superstructure (LF)

Condition State 1: Weathering steel element has little or no deterioration. The protective oxide coating isuniform and tightly adhered. Corrosion has not progressed beyond the intended layer of surface rust -there is no notable section loss. Painted areas “high corrosion areas” (if any) have little or nodeterioration.

Condition State 2: Weathering steel element has minor to moderate deterioration. The protective oxidecoating has partially failed - the surface may be dusty or granular. While corrosion may have progressedbeyond the surface layer (the surface layer may be flaking off in small areas), any section loss isincidental. Painted “high corrosion areas” (if any) may have minor to moderate deterioration. Element isin proper position and alignment - all connections are sound. Note: elements that have been repaired orreinforced should generally not be rated above Condition State 2.

Condition State 3: Weathering steel element has extensive deterioration, but the load-carrying capacityof the member has not been significantly reduced. The protective oxide coating has extensive failure -large areas of the surface layer may be flaking off. There may be extensive corrosion. While there may besignificant section loss, structural analysis is not yet required (section loss is less than 10% of theeffective section). Painted “high corrosion areas” (if any) may have extensive or complete failure.Element may be slightly out of position or alignment - connections may have started to come loose.

Condition State 4: Weathering steel element has severe or critical deterioration. The load-carryingcapacity of the member has been significantly reduced - structural analysis or immediate repairs may berequired. The protective oxide coating has failed. Section loss may exceed 10% of the effective section.The element may be severely damaged or significantly out of position or alignment - connections mayhave failed.


3.4.3 Reinforced Concrete Elements

These elements apply to structural members constructed of cast-in-place or pre-cast reinforced concrete(not pre-stressed or post-tensioned concrete).

Element #105: Reinforced Concrete Box Girder (LF) Element #110: Reinforced Concrete Girder or Beam (LF) Element #116: Reinforced Concrete Stringer (LF) Element #144: Reinforced Concrete Arch (LF) Element #155: Reinforced Concrete Floorbeam (LF) Element #205: Reinforced Concrete Column (EA) Element #210: Reinforced Concrete Pier Wall (LF) Element #215: Reinforced Concrete Abutment (LF) Element #220: Reinforced Concrete Footing (EA) Element #227: Reinforced Concrete Piling (EA) Element #234: Reinforced Concrete Pier Cap/Bearing Cap (LF) Element #375: Pre-cast Concrete Channels (LF) Element #385: Reinforced Concrete Arch Spandrel Column (EA) Element #387: Reinforced Concrete Wingwall (EA) Element #414: Reinforced Concrete Arch Spandrel Wall (LF)

Condition State 1: Reinforced concrete element has little or no deterioration. There may be minorcracking, leaching, staining, or surface scale - there is no notable delamination or spalling. The memberhas no impact damage or repair patches.

Condition State 2: Reinforced concrete element has minor to moderate deterioration. There may bemoderate cracking, leaching, staining, or surface scale. Minor delaminations or spalls may be present, butthere is little or no exposure of steel reinforcement. Element is in proper position and alignment - allconnections are sound. Repair patches (if any) remain sound. Note: elements that have been repaired orreinforced should generally not be rated above Condition 2.

Condition State 3: Reinforced concrete element has extensive deterioration, but the load-carryingcapacity of the element has not been significantly reduced. There may be extensive cracking, leaching,staining, or scale. Structural cracking (from shear or flexure) may be present. Delaminations and spallsmay be prevalent. Exposed reinforcement may have corrosion, but any section loss is incidental and doesnot significantly affect the strength and/or serviceability of either the element or the bridge. Element maybe slightly out of position or alignment - connections may have started to come loose.

Condition State 4: Reinforced concrete element has severe or critical deterioration. The load-carryingcapacity of the element has been significantly reduced - structural analysis or immediate repairs may berequired. Severe structural cracking (from shear or flexure) may be present. Spalling may be extensive orsevere - exposed reinforcement may have significant section loss. The element may be severely damagedor significantly out of position or alignment - connections may have failed.


3.4.4 Prestressed/Post-Tensioned Concrete Elements

These elements apply to structural members constructed of either prestressed or post-tensioned concrete.

Element #104: Prestressed Concrete Box Girder (LF) Element #109: Prestressed Concrete Girder or Beam (LF) Element #115: Prestressed Concrete Stringer (LF) Element #143: Prestressed Concrete Arch (LF) Element #154: Prestressed Concrete Floorbeam (LF) Element #204: Prestressed Concrete Column (EA) Element #226: Prestressed Concrete Piling (EA) Element #233: Prestressed Concrete Pier Cap/Bearing Cap (LF) Element #374: Prestressed Concrete Double, Quad, Bulb, or Inverted Tees (LF) Element #402: Prestressed Concrete Voided Slab Panels (LF)

In a properly designed pre-stressed member, structural cracking (flexure or shear) should not developunder normal service loads. On pre-stressed concrete members, all cracks are significant - they should bemeasured and documented. Cracks provide openings for water and chlorides, which can lead to stresscorrosion - the inspector should note any rust stains that may indicate corrosion of the pre-stressingstrands.

Condition State 1: Pre-stressed concrete element has little or no deterioration. There is no notablecracking, staining, delamination or spalling. The member has no impact damage or repair patches.

Condition State 2: Pre-stressed concrete element has minor deterioration. There may be minor (non-structural) cracking, leaching, staining, or surface scale. There is no structural cracking (from shear orflexure). Minor delaminations or spalls may be present, but there is no exposure of the tensioning steel.Element is in proper position and alignment - all connections are sound. Repair patches (if any) remainsound. Note: elements that have been repaired or reinforced should generally not be rated aboveCondition 2.

Condition State 3: Pre-stressed concrete element has moderate deterioration, but the load-carryingcapacity of the element has not been significantly reduced. There may be moderate cracking, leaching,staining, or scale. Structural cracking (from shear or flexure) may be present. Delaminations and spallsmay be present. While the tensioning steel may be exposed, any section loss is incidental and does notsignificantly affect the strength and/or serviceability of either the element or the bridge. Element may beslightly out of position or alignment - connections may have started to come loose.

Condition State 4: Pre-stressed concrete element has severe or critical deterioration. The load-carryingcapacity of the element has been significantly reduced - structural analysis or immediate repairs may berequired. Severe structural cracking (from shear or flexure) may be present. Spalling may be extensive orsevere - exposed tensioning steel may have significant section loss. The element may be severelydamaged or significantly out of position or alignment - connections may have failed.


3.4.5 Timber Elements

These elements apply to timber structural members of any type - this includes sawn, glue-lam, or stress-laminated timber members.

Element #111: Timber Girder or Beam (LF) Element #117: Timber Stringer (LF) Element #135: Timber Truss or Arch (LF) Element #156: Timber Floorbeam (LF) Element #206: Timber Column (EA) Element #216: Timber Abutment (LF) Element #228: Timber Piling (EA) Element #235: Timber Pier Cap/Bearing Cap (LF) Element #386: Timber Wingwall (EA) Element #415: Timber Transverse Stiffener Beam - Timber Slab Spans (LF)

Condition State 1: Timber element has little or no deterioration. There may be minor cracks, splits, orchecks. There is no decay, fire damage, or structural distress (crushing or sagging). There is no impactdamage.

Condition State 2: Timber element has minor to moderate deterioration. There may be moderatecracking or splitting. There may be minor decay or fire damage, but there is no significant structuraldistress (crushing, or sagging). Element is in proper position and alignment - all connections are sound.Repaired/reinforced areas (if any) remain sound. Note: elements that have been repaired or reinforcedshould generally not be rated above Condition 2.

Condition State 3: Timber element has extensive deterioration - repairs may be required, but the load-carrying capacity has not been significantly reduced. There may be extensive cracking or splitting. Decay,infestation, or fire damage may have resulted in a slight reduction of cross-sectional area. There may beslight crushing or sagging. Element may be slightly out of position or alignment - connections may havestarted to come loose.

Condition State 4: Timber element has severe or critical deterioration (significant loss of cross-sectionalarea). The load-carrying capacity of the element has been significantly reduced - structural analysis orimmediate repairs may be required. Timber element may have severe cracking or structural failure. Theremay be advanced decay, infestation, or fire damage. There may be severe crushing or sagging. Theelement may be severely damaged or significantly out of position or alignment - connections may havefailed.


3.4.6 Masonry, Other, or Combination Material Elements

These elements apply to masonry of any type, shape, or configuration. These elements can also apply tostructural elements constructed of any material (or combination of materials) not adequately described bythe other elements. Note: masonry arches with spans of less than 20 ft. can be rated using structuralelement #243 (Masonry or Other Material Culvert).

Element #145: Masonry, Other, or Combination Material Arch (LF) Element #211: Masonry, Other, or Combination Material Pier Wall (LF) Element #217: Masonry, Other, or Combination Material Abutment (LF) Element #416: Masonry, Other, or Combination Material Pier Cap/Bearing Cap (LF) Element #417: Masonry, Other, or Combination Material Column (EA) Element #418: Masonry, Other, or Combination Material Wingwall (EA) Element #420: Masonry, Other, or Combination Material Arch Spandrel Wall (LF)

Condition State 1: Element has little or no deterioration - there may be minor defects or staining.Masonry may have minor weathering - masonry blocks are properly aligned (mortar joints are sound)Timber may have minor cracks or splits. Concrete may have minor cracking or scale. Steel has little or nocorrosion. Protective coatings (if any) remain sound.

Condition State 2: Element has minor to moderate deterioration (no repairs are necessary). Masonry mayhave moderate weathering (cracking or spalling may be evident). Masonry blocks may be slightlymisaligned. Mortar joints may have minor deterioration (leakage or weed intrusion may be evident).Timber may have moderate splitting, decay or fire damage, but there is no crushing or sagging. Concretemay have moderate cracking, scaling, leaching, or staining - there may be some delamination or spalling.Steel may have moderate corrosion (little or no section loss). Protective coatings may have minor tomoderate failure. Repaired/reinforced areas (if any) remain sound. Note: elements that have been repairedor reinforced should typically not be rated above Condition State 2.

Condition State 3: Element has extensive deterioration - repairs may be required, but the load-carryingcapacity of the element has not been significantly reduced. Masonry may have extensive weathering,cracking, or spalling. Masonry blocks may significantly misaligned (offset, tipped, or settled). Mortarjoints may have significant deterioration (extensive leakage or weed intrusion). Timber may haveextensive cracking or splitting, significant decay or fire damage, or slight crushing or sagging. Concretemay have extensive cracking, scaling, leaching, or rust/water staining. Delamination and spalling may beprevalent (exposed reinforcement may have section loss). Steel components may have extensive corrosion(significant section loss). Protective coatings may have extensive or complete failure.

Condition State 4: Element has severe damage or deterioration. The load-carrying capacity of theelement has been significantly reduced - structural analysis or immediate repairs may be required.Masonry may have severe weathering, cracking, or spalling. Masonry blocks may be severely misaligned(offset, tipped, or settled). Concrete may have severe structural cracking or spalling. Timber may havesevere structural decay (significant loss of cross-sectional area), cracking, sagging, or crushing. Steelcomponents may have severe section loss.


3.5 Other Structural Elements

This section includes ratings descriptions for structural elements that could not be adequately describedby the material groupings (Section 3.4). This includes bridge elements (bearings, pin & hangerassemblies, and hinge bearings) where the condition descriptions emphasize proper function, as well aselements for steel cables, tunnels, cast-in-place piling, and secondary members.

3.5.1 Bearings

The primary function of a bearing is to transmit loads from the superstructure to the substructure - thereare two basic types of bearings, expansion and fixed…

Expansion bearings permit longitudinal movement of the superstructure due to thermal expansionand contraction. Most expansion bearings allow for rotation of the superstructure due to live loaddeflection - some are designed to restrict lateral movement of the superstructure.

Fixed bearings resist longitudinal movement of the superstructure due to thermal expansion andcontraction. Most fixed bearings allow for rotation of the superstructure due to live loaddeflection, and to resist lateral movement of the superstructure.

A bearing assembly typically consists of the following components…

Sole Plate: The sole plate protects the superstructure member, and transfers load from thesuperstructure to the bearing.

Bearing: The bearing transfers load from the sole plate to the masonry plate. Bearings mayincorporate sliding plates, rollers, rockers, pins, or elastomeric pads to allow for longitudinal orrotational movement of the superstructure.

Masonry Plate: The masonry plate distributes load from the bearing to the supportingsubstructure unit (abutment, pier, or footing). Some bearings bear directly upon the bearing seat.

Anchorage: Bearings that resist longitudinal or lateral movement (or uplift forces) require ananchorage system - this typically consists of steel rods drilled (or cast) into the substructure unit.


Inspection and Condition Rating of Bridge Bearings

Bearings should be examined for deterioration, function, alignment, as well as the soundness of theanchorage and substructure support. All of these factors should be taken into consideration when rating abearing element. There are six bearing elements - they are all rated on a scale of 1-3, and are listed as an“each” quantity (the bridge design plans may need to be referenced to verify the type and quantity ofbearing elements).

Element #310 - Elastomeric (Expansion) Bearings Element #311 - Expansion Bearings Element #312 - Enclosed or Concealed Bearings Element #313 - Fixed Bearings Element #314 - Pot Bearings Element #315 - Disk Bearings

The importance of inspecting and properly maintaining bridge bearings should not be underestimated -seemingly minor bearing problems can become worse if ignored, eventually resulting in serious problemsfor the bridge.

Bearing malfunction can damage adjacent deck, superstructure, or substructure elements. Severe bearing misalignment often indicates significant problems elsewhere on the bridge (such

as substructure settlement or tipping). Loss of bearing area (or anchorage failure) can result in collapse of a span.

Bearing Malfunction: The most common bearing malfunction is the seizing (or “freezing”) of expansionbearings due to corrosion or debris. Bearings are typically located below deck joints, a highly corrosiveenvironment. Debris (such as sand, dirt, and flaking rust) can restrict expansion, accelerate corrosion,increase wear, and prevent adequate inspection of the bearing. Sliding plate, roller, and rocker bearingsprovide numerous locations for debris and moisture to collect. Expansion bearings should be examinedfor any obvious visual evidence of recent movement (such as scraped paint, wear, or fretting rust). If noneis present, the inspector should take bearing measurements, or examine adjacent bridge components (suchas deck joints, railings, or curb plates) for evidence of recent expansion or contraction.

Bearing malfunction can also result from bearing components that are worn, misaligned, broken, loose, ormissing. Contact surfaces (plates, rollers, rockers, and pins) should be examined for wear and freedom ofmovement. Loose bearing components may be identified by noise (or movement) when the bridge issubjected to live loads.

Recent movement evident on expansion bearing Corroded (possibly frozen) expansion bearing

Bearings - Thermal Expansion & Contraction: The magnitude of the longitudinal movement of abridge superstructure is dependent upon three factors - the coefficient of thermal expansion (steel andconcrete are similar), the temperature range, and the contributing structure length. As the temperature inMinnesota may range from -30 degrees F up to 110 Degrees F, a bridge bearing must be able toaccommodate about 1-1/8” of longitudinal movement for every 100 ft. of structure length. In Minnesota,expansion bearing are typically designed to be in the neutral (centered) position at approximately 40degrees F (nationally, the neutral temperature is assumed to be 68 degrees F).

Expansion bearings should be periodically measured to ensure that the bearing alignment is appropriatefor the current temperature. The horizontal (longitudinal) distance from the neutral alignment should berecorded, as well as the tilt angle of rocker bearings. Bearing measurements should be taken to the nearest1/8”, and the temperature at the time of the measurement should be recorded. Thermal expansion orcontraction which exceeds the bearing design limits can result in bearing failure - sliding plates may tipand lock, or rocker bearings may bind. The adjacent deck, superstructure, and substructure should beexamined for contacting surfaces that might be preventing proper expansion.

Bearings - Lateral Movement and Uplift: Expansion bearings are typically restrained from lateralmovement by guide tabs, keeper bars, pintles, pin caps, or other mechanisms. Guide tabs should beexamined for binding, particularly on skewed or curved bridges. Keeper bars on roller bearings can seizedue to corrosion or debris - failure of keeper bars can result in roller misalignment. Pintles can shear off -exposed pintles may indicate excessive longitudinal movement.

Note: Lateral restraint is sometimes provided by shear keys, shear lugs, or other devices that areincorporated into end diaphragms or floorbeams. Lateral restraint systems that are separate from thebridge bearings may be rated using Element #380 (Secondary Structural Elements).

Some bearings are also designed to resist uplift of the bridge superstructure - uplift forces may be presenton curved bridges, anchor spans, steel pier caps, steel arch bridges, or on short end spans of continuousbridges. An uplift restraint system typically consists of tension members such as anchor bolts or eyebars,and may incorporate a counterweight. Uplift restraints should be examined for section loss, cracking,binding, or connection failure - uplift restraint bolts may require periodic ultrasonic examination.

Bearings - Seats & Anchor Bolts: The bearing seats and anchor bolts should be examined for anyevidence of deterioration or distress. Cracking or spalling of the bearing seat may indicate bearing failure- deterioration of the bearing seat can eventually result in loss of bearing area. Anchor bolts that are bent(or contacting the ends of slotted plates) may indicate excessive expansion or substructure movement. Asonly the upper portion of anchor bolts are visible for inspection, nondestructive testing may be necessary.The position of bearing masonry plates should be measured and compared to the original plans.

Loss of bearing area due to substructure deterioration Anchor bolt failure (masonry plate has shifted)


Element #310 - Elastomeric (Expansion) Bearings

This element applies to rectangular elastomeric bearing pads that facilitate expansion via deformation.MnDOT spec. #3741 covers elastomeric bearing pads - they are comprised of alternating layers ofelastomer (100% virgin chloroprene) and 1/8” thick steel plates, which are bonded together. Older bridgesmay have solid (non-reinforced) pads, or pads laminated with fiberglass plates. A curved steel pintle plateis usually placed on top of the pad to allow rotation due to deflection (in some cases this is vulcanized tothe pad). Elastomeric expansion bearings may be restrained against lateral movement or uplift forces.

Elastomeric bearings generally require less maintenance than mechanical expansion bearings, as they areless susceptible to debris and corrosion. Elastomeric pads should be examined for splitting, tearing,delamination, or excessive bulging. Elastomeric bearings can accommodate longitudinal movement up toapproximately 25% of the pad thickness - the longer the span, the thicker the pad required. While the paddeformation and orientation should correspond with the current temperature, the orientation also dependsupon the temperature when the bearing was installed. As elastomeric pads have a tendency to “walk” outfrom beneath the sole plate, any movement or misalignment should be noted.

Condition State 1: Elastomeric expansion bearing is in good condition and is functioning as intended.The bearing pad is properly positioned - deformation and orientation is appropriate for the currenttemperature. The elastomeric covering may have minor deterioration (the steel reinforcement layers arenot exposed). Pintle plates, restraints, or anchor bolts (if present) are sound, properly positioned, andfunctioning as intended. The bearing seat is in good condition (there is no loss of bearing area).

Condition State 2: Elastomeric expansion bearing has moderate deterioration - bearing function may beslightly impaired. Bearing pad deformation may be near the design limits (25% of the pad thickness), orthe orientation may be inappropriate for the current temperature (resetting may be recommended). Thepad may have bulged, deformed laterally, or moved slightly out of position. The elastomeric coveringmay have split or torn (steel reinforcement layers may be exposed). Pintle plates, restraints, or anchorbolts (if present) may have moderate deterioration, slight binding, or may be slightly out of position). Thebearing seat may have moderate deterioration (there may be a slight loss of bearing area).

Condition State 3: Elastomeric expansion bearing has severe deterioration - resetting or replacementmay be required. Bearing pad deformation may be beyond the design limits (25% of the pad thickness) -the pad may severely bulged or significantly out of position. The elastomeric covering may have failed(steel reinforcement layers may have severe corrosion or de-bonding). Pintle plates, restraints, or anchorbolts (if present) may have failed, or may be significantly out of position. Bearing seat may have severedeterioration (there may be significant loss of bearing area) - supplemental supports or load restrictionsmay be warranted.


Element #311 - Expansion Bearings

This element applies to mechanical expansion bearings of any type - such as sliding plate bearings, rollerbearings, or rocker bearings. Expansion bearings allow for longitudinal movement of the superstructuredue to thermal expansion and contraction. Most expansion bearings allow rotation of the superstructuredue to live load deflection - some may be designed to restrict lateral movement or uplift forces.

Sliding plate bearings allow longitudinal movement by one steel plate sliding upon another (acurved pintle plate is sometimes included to allow for rotation). Sliding plate bearings oftenincorporate bronze plates or lubricants to facilitate movement. Lateral restraint may be providedby guide tabs, or by anchor bolts extending up through slotted plates.

A roller bearing consists of a horizontal steel cylinder that “rolls” between the sole plate andmasonry plate as the superstructure expands and contracts. The bearing may have a single rolleror multiple rollers (“rollernest bearing”). Lateral restraint may be provided by pintles (on the top& bottom of the roller), or keeper bars attached the ends of the rollers.


Rocker bearings are typically comprised of a curved rocker plate (bearing on the masonry plate),that is connected to the sole plate with an upper pin. The bearing may have a single rocker ormultiple rockers (“rockernest bearings”). Lateral restraint may be provided by pintles (attached tothe masonry plate), pin caps, or anchor bolts extending up through slotted slates.

Condition State 1: Expansion bearing is in good condition and is functioning as intended. Bearingalignment is within design limits and is appropriate for the current temperature. Bearing assembly isrelatively free of debris (no restriction of movement). Paint system (if present) may have somedeterioration - corrosion may be present, but there is no significant section loss. Lubrication system (ifany) is functioning properly. All bearing components (sliding plates, rockers, rollers, pins, etc.) are intactand properly positioned. Lateral guide/restraint system (or uplift restraint system, if present) is in goodcondition. Anchor bolts are bearing seat are sound (there is no loss of bearing area).

Condition State 2: Expansion bearing has moderate deterioration - bearing function may be slightlyrestricted (cleaning, painting, or lubrication may be recommended). Bearing alignment may be at or nearthe design limits (or inappropriate for the current temperature), but is still tolerable. Bearing assemblymay have extensive corrosion (section loss may be present), or may be covered with debris. Lubricationsystem may have failed. Primary bearing components (sliding plates, rockers, rollers, pins, etc.) may bemoderately worn or slightly out of alignment. Secondary bearing components (cotter pins, etc.) may beloose or missing. The lateral guide/restraint system (guide tabs, keeper bars, pintles, pin caps, etc.) may bemoderately worn or slightly out of alignment (there may be minor binding). Uplift restraint system (ifpresent) may have moderate deterioration, but is still functioning as intended. Anchor bolts may becorroded or bent, but remain intact. The bearing seat may have moderate deterioration (there may be aslight loss of bearing area).

Condition State 3: Expansion bearing has severe deterioration, and is no longer functioning as intended(repair or replacement may be necessary). Bearing alignment may be beyond design limits. Bearingmechanism may be frozen (seized) or severely restricted due to corrosion or debris. Primary bearingcomponents (sliding plates, rockers, rollers, pins, etc.) may severe section loss, wear, or misalignment -they may have jammed, come loose or otherwise failed. The lateral guide/restraint system (guide tabs,keeper bars, pintles, or pin caps) may have sheared off, bound, or otherwise failed. Uplift restraint systemmay have failed. Anchor bolts may have failed. Bearing seat may have severe deterioration (there may besignificant loss of bearing area) - supplemental supports or load restrictions may be warranted.


Element #312 - Enclosed or Concealed Bearings

This element applies to bearing assemblies that are enclosed or concealed, and are not visible for detailedinspection. This can include either fixed or expansion bearings.

Condition State 1: Enclosed/Concealed bearing is in good condition and is functioning as intended.Horizontal, lateral and vertical alignment is within limits and is appropriate for the current temperature.The bearing seat is sound (there is no loss of bearing area).

Condition State 2: Enclosed/Concealed bearing has moderate deterioration (repairs may berecommended). Horizontal, lateral or vertical alignment may be near design limits (or inappropriate forthe current temperature). The bearing seat may have moderate deterioration (there may be a slight loss ofbearing area).

Condition State 3: Enclosed/Concealed bearing has severe deterioration - repair or replacement may benecessary. Horizontal, lateral or vertical alignment may be beyond the design limits. Bearing seat mayhave severe deterioration (there may be significant loss of bearing area) - supplemental supports or loadrestrictions may be warranted.

Element #313 - Fixed Bearings

This element applies to bearings that are fixed against longitudinal movement of the superstructure. Fixedbearings may incorporate a pin or a thin elastomeric pad to allow rotational movement (from live loaddeflection of the superstructure). Fixed bearings are typically designed to resist transverse movement, andmay be designed to resist uplift forces.

Condition State 1: Fixed bearing is in good condition and is functioning as intended. Bearing assemblyis relatively free of debris (no restriction of movement). Paint system (if present) may have somedeterioration - corrosion may be present, but there is no significant section loss. All bearing componentsare intact and properly positioned. Anchor bolts are bearing seat are sound (there is no loss of bearingarea).

Condition State 2: Fixed bearing has moderate deterioration - cleaning or painting may berecommended. Bearing assembly may have extensive corrosion (section loss may be present), or may becovered with debris. Primary bearing components (castings, pins, pads, etc.) may be moderately worn orslightly out of alignment. Secondary bearing components (cotter pins, lead plates, sole plate bolts, etc.)may be working out, loose, or missing. Anchor bolts may be corroded, but remain intact. The bearing seatmay have moderate deterioration (there may be a slight loss of bearing area).

Condition State 3: Fixed bearing has severe deterioration, and is no longer functioning as intended(repair or replacement may be necessary). Primary bearing components may have severe section loss,wear, misalignment, or may have otherwise failed. Anchor bolts may have failed. Bearing seat may havesevere deterioration (there may be significant loss of bearing area) - supplemental supports or loadrestrictions may be warranted.


Element #314: Pot BearingsElement #315: Disk Bearings

Pot and Disk bearings allow for multi-dimensional rotational movement - these are specialized bearingsused only for high loads (long spans, steel pier caps, or railroad bridges). Pot/Disk bearings may be eitherfixed or expansion.

Pot bearings consist of a shallow steel piston that rests within a steel cylinder (which contains aconfined elastomer). Typically, only the perimeter edge of the elastomer is visible for inspection.

Disc bearings consist of a shallow steel piston that rests within a steel cylinder (which contains ahard plastic disc. Typically, the disc is enclosed within the assembly and is not visible forinspection. Note: high load bearings which utilize a semi-spherical steel bearing plate can alsobe considered to be a “Disc” bearing.

The upper piston plate should be properly seated (and positioned) within the lower cylinder plate. Anyexposed portions of the elastomer or disc should be examined for splitting, tearing, or extrusion.

On expansion Pot bearings, the upper plate typically has a stainless steel plate (with a “mirror finish”)welded to the underside, while the lower plate typically has PFTE (polytetrafluoroethylene) bonded to thetop surface. This combination provides an extremely low friction sliding surface (lubrication is notrequired). The upper sliding plate should be examined evidence of separation (such as cracked welds) ofthe stainless steel - the extent of any recent movement can often be determined by examining the stainlesssteel plate. The lower plate should be examined for any de-bonding of the PTFE. Expansion Pot bearingsmay be “guided” (lateral movement is restricted) or “non-guided” (free to move laterally). On unguidedexpansion bearings, note any evidence of lateral movement. On guided expansion bearings, look forevidence of wear, binding, or deterioration of the guide system.

Condition State 1: Pot/Disc bearing is in good condition and is functioning as intended. On expansionbearings, alignment is within design limits and is appropriate for the current temperature. Bearing is freeof corrosion and debris (no restriction of movement). All bearing components are properly aligned andproperly seated. Confined elastomer has little or no deterioration - there is no evidence of the elastomerextruding from the cylinder. Guide/restraint devices (if present) are intact and are functioning properly.Anchor bolts are bearing seat are sound (there is no loss of bearing area).

Condition State 2: Pot/Disc bearing has moderate deterioration - bearing function may be slightlyrestricted (cleaning or repair may be recommended). On expansion bearings, alignment may be neardesign limits (or inappropriate for the current temperature), but is still tolerable. Bearing assembly mayhave corrosion or may be covered with debris (there may be a slight restriction of movement). Primarybearing components (piston, cylinder, sliding plate, etc.) may be slightly tipped, offset, or out ofalignment. Confined elastomer may have some deterioration, or may have started to extrude along theedge of the cylinder. Guide/restraint devices (if present) may be worn, loose, or out of alignment (theremay be minor binding). Anchor bolts may be corroded, but remain intact. The bearing seat may havemoderate deterioration (there may be a slight loss of bearing area).

Condition State 3: Pot/Disc bearing has severe deterioration, and is no longer functioning as intended(repair or replacement may be necessary). On expansion bearings, alignment may be beyond designlimits. Bearing mechanism may be frozen (seized) or severely restricted Primary bearing components maysevere section loss, wear, or misalignment - they may have jammed, come loose or otherwise failed.Confined elastomer may have severe deterioration, or may be actively extruding from the cylinder.Guide/restraint devices (if present) may have failed. Anchor bolts may have failed. Bearing seat may havesevere deterioration (there may be significant loss of bearing area) - supplemental supports or loadrestrictions may be warranted.


3.5.2 Pin & Hanger (or Fixed Pin) Assemblies

On continuous steel bridges with cantilever or suspended spans (where the end of one span is supportedby an adjacent span), the connection detail may consist of a pinned assembly. A pin & hanger assemblytypically consists of two vertical hanger plates with pinned connections at the top and bottom - this allowsboth rotation and longitudinal movement of the superstructure. A fixed pin assembly typically consists ofa single pin - this allows rotation, but restricts longitudinal movement of the superstructure.

Pinned assemblies are relatively rare in Minnesota - most are found on multiple girder/beam bridgesconstructed from 1935-1975, but some can be found on long-span two-girder or truss bridges (on trussbridges, the hanger member may be similar to other truss members). On any bridge that carries highwaytraffic, pinned assemblies are considered to be “special features”, and require periodic ultrasonicexamination (see MnDOT Tech Memo #02-22-B-01). On two-girder or truss bridges (that carry highwaytraffic), pinned assemblies are considered to be “fracture critical” members - the failure of a pin or hangerplate could result in the collapse of a span.

On a typical suspended span, one end is supported by fixed pin assemblies, while the expansion end issupported by pin & hanger assemblies To prevent lateral movement of the superstructure, the expansionend will often incorporate a guide/restraint system (such as a wind transfer pin assembly). Some bridgesin Minnesota (particularly along the Red River Valley) have “swivel hinges” - the center girder will havea fixed pin assembly, while the other girders will all have pin & hanger assemblies.

Pinned assemblies should be examined for deterioration, function, alignment, as well as the soundness ofthe superstructure support. All of these factors should be taken into consideration when rating a pinnedassembly. All components of a pinned assembly (pins, plates, pin caps, nuts, washers, spacers, etc.)should be examined for wear, corrosion, defects, cracks, bending, loosening or misalignment. Note:Severe pack rust can deform hanger plates or result in failure of pinned connections.

Periodic measurements should be taken to verify the proper function of pin & hanger assemblies (be sureto record the temperature at the time of inspection). As a frozen pin will transfer additional bendingstresses to the hanger plates, any significant restriction of a pin & hanger assembly should be identifiedand analyzed immediately. Note: While the presence of fretting rust (a red-colored dust resulting from thewearing of steel surfaces) indicates that recent movement has occurred, it may also indicate inadequatelubrication.

Pin & Hanger Assembly Fixed Pin Assembly


Element #161: Pin & Hanger (or Fixed Pin) Assembly

Element #161: Pin & Hanger (or Fixed Pin) Assembly - Painted Steel

There are two AASHTO CoRe elements for pinned assemblies. However, MnDOT only uses Element#161 (Element #160 should not be used - the condition rating description for this element is not includedin this manual). Element #161 should be used for all pin & hanger (or fixed pin) assemblies - this is an“each” item, a single condition state must be determined for each pinned assembly.

Condition State 1: Pinned assembly has little or no deterioration - it is free of debris and properlyaligned. All components (pins, plates, pin caps, nuts, washers, spacers, etc.) are in good condition. Paintsystem (if present) is sound - there is no notable corrosion (or section loss). Supporting steelsuperstructure has little or no deterioration.

Condition State 2: Pinned assembly has minor deterioration. There may be minor debris, but there is norestriction of movement - lubrication system (if present) is functioning properly. Assembly components(pins, plates, pin caps, nuts, washers, spacers, etc.) may have minor wear or deterioration, but remain inproper position. Longitudinal alignment is within design limits and is appropriate for the currenttemperature. Lateral restraint/guide systems (if present) are functioning as intended - there is no notablelateral misalignment. Paint system (if present) may have some deterioration - corrosion may be present,but any section loss (or pack rust) is incidental. Supporting steel superstructure may have minordeterioration.

Condition State 3: Pinned assembly has moderate deterioration, but is still functioning as intended.Debris or corrosion may have resulted in a slight restriction of movement (cleaning and/or lubricationmay be recommended). Pins or plates may have moderate wear (fretting rust may be present). Primaryconnections (nuts, pin caps, etc.) remain intact - secondary components (washers, spacers, cotter pins,etc.) may be loose or misaligned. Longitudinal alignment may be near the design limits, or may besomewhat inappropriate for the current temperature. Lateral restraint/guide systems may be worn or loose- there may be slight lateral misalignment. Paint system (if present) may have extensive deterioration -surface corrosion may be prevalent (notable section loss or pack rust may be present). Supporting steelsuperstructure may have moderate deterioration.

Condition State 4: Pinned assembly has extensive deterioration - the function may be impaired, but theload-carrying capacity has not been significantly reduced. Debris or corrosion may be restrictingmovement (cleaning and/or lubrication may be required). Pins or plates may have extensive wear or slightdeformation (cracks or other defects may be present). Primary connections (nuts, pin caps, etc.) may havestarted to work loose - secondary components (washers, spacers, cotter pins, etc.) may be missing.Longitudinal alignment may be at the design limits (contacting or binding), or may be completelyinappropriate for the current temperature. Lateral restraint/guide systems may have failed, or there may beexcessive lateral misalignment. Paint system (if present) may have failed - there may be extensivecorrosion, with significant section loss (or pack rust). Supporting steel superstructure may have extensivedeterioration.

Condition State 5: Pinned assembly has severe or critical deterioration. The load-carrying capacity hasbeen significantly reduced - structural analysis or immediate repairs may be required. Movement may becompletely restricted (assembly may be frozen or binding). Pins or plates may have severe wear,deformation, or cracking. There may be severe longitudinal or lateral misalignment. Primary connectionsmay have failed. There may be severe section loss or pack rust. Supporting steel superstructure may havesevere or critical deterioration.


3.5.3 Hinge Bearing Assemblies

On continuous bridges with cantilever or suspended spans (where the end of one span is supported by anadjacent span), the connection detail may consist of a hinge bearing assembly. Hinge bearings may beexpansion (permitting longitudinal movement of the superstructure) or fixed (resisting longitudinalmovement of the superstructure). Most hinge bearings are designed to allow rotation of the superstructuredue to live load deflection - some are designed to restrict lateral movement of the superstructure. Hingebearings can include a variety of bearing assembly types (rocker, roller, sliding plate, or elastomeric pad).

In Minnesota, hinge bearings are very common on steel multi-beam bridges constructed in the 1960’s and1970’s - they can also be found on concrete box girder and steel truss bridges (they are seldom used innew bridges). Incorporating a hinge bearing simplifies structural analysis, as by allowing rotation, thebending moments are isolated. Hinge bearings are typically “cantilevered” (offset from the piers), toreduce deterioration of the substructure from leaking deck joints.

While hinge bearing assemblies are not classified as “special features” (like pin & hanger assemblies),these details should be given special attention during each inspection. A malfunctioning hinge bearingcould result in damage to adjacent deck, superstructure, or substructure elements. Misalignment of ahinge bearing may indicate significant problems elsewhere on the bridge (such as substructure settlementor tipping).

Sliding Plate Hinge Bearing

Rocker Hinge Bearing Roller Hinge Bearing

Elastomeric Hinge Bearing


As there are no AASHTO CoRe elements to rate the condition of hinge bearing assemblies, MnDOT hasadded two structural elements…

Element #373: Steel Hinge Assembly (Painted or Unpainted) Element #379: Concrete Hinge Assembly

Element #373 applies to hinge bearings on steel superstructures (it is rated on a scale of 1-5); Element#379 applies to hinge bearings on concrete superstructures (it is rated on a scale of 1-4). Hinge bearingassemblies should be examined for deterioration, function, alignment, as well as the soundness of thesuperstructure support. All of these factors should be taken into consideration when rating a hinge bearingelement.

During a routine inspection, hinge bearings are typically observed from ground level (binoculars arehelpful). If problems are observed during a routine inspection, an in-depth inspection (using some type ofaccess equipment) should be scheduled. The following items should be emphasized when inspecting ahinge bearing assembly…

Hinge bearing assemblies should be examined for corrosion or debris. Adjacent deck joints anddeck drainage systems should be examined for leakage, clogging, or other malfunction that mightbe subjecting the hinge bearing to excessive water, salt, or debris.

The hinge bearing components (rockers, rollers, sliding plates, elastomeric pads, pins, nuts,washers, cotter pins, spacers & guide tabs) should be examined for wear, corrosion, defects,cracks, bending, loosening or misalignment. Excessive movement (or noise) at the hinge bearingunder live loads may indicate bearing malfunction.

On expansion hinge bearings, proper function is a primary concern - the inspector should verifythat longitudinal movement is not restricted (any significant restriction should be identified andanalyzed immediately). Obvious visual evidence of recent movement (such as scrape marks oncontact surfaces) should be noted. The adjacent superstructure and deck should be examined forany evidence of contacting (or binding) that might be restricting expansion. To verify properfunction, periodic measurements should be taken (preferably at a clean, easily identifiablelocation) - be sure to record the temperature when the measurements were taken. If the hingebearings cannot be accessed up-close, measurements can be taken at adjacent deck joints, curbplates, or railings.

The longitudinal and lateral alignment of the hinge bearing should be observed and noted (anysignificant misalignment should be identified and analyzed immediately). On expansion hingebearings, the longitudinal alignment should be appropriate for the current temperature, and thealignment of adjacent hinge bearings should be similar.

Like any bearing assembly, the condition of the bearing support member is also of concern, andmay affect the rating. The superstructure adjacent to the hinge bearing assembly should beexamined for deterioration (or evidence of structural distress). On steel beams, the webs, flanges,and bearing stiffeners should be examined for corrosion, section loss, bulking, or cracking. Onconcrete box girders, the concrete surfaces should be examined for structural cracking, leaching,rust staining, delamination, or spalling (internal inspection of the hinge area is recommended).


Element #373: Steel Hinge Assembly (Painted or Unpainted)

This element applies to hinge bearing assemblies on steel girders, beams, stringers, trusses (or other steelbridges). This includes hinge bearing assemblies of any type (rocker, roller, sliding plate, or elastomericpad), and includes both expansion and fixed hinge bearing assemblies. While this element typically refersto cantilever hinges on steel beams or girders, it can be used to rate any bearing assembly where a steelsuperstructure element bears upon another steel superstructure element. This is an “each” item, a singlecondition state must be determined for each hinge assembly.

Condition State 1: Steel hinge bearing assembly has little or no deterioration - it is free of debris andproperly aligned. All bearing components (rockers, rollers, sliding plates, pads, pins, nuts, washers, cotterpins, etc.) are in good condition. Paint system (if present) is sound - there is no notable corrosion.Supporting steel superstructure has little or no deterioration.

Condition State 2: Steel hinge bearing assembly has minor deterioration. There may be minor debris, butthere is no restriction of movement - lubrication system (if present) is functioning properly. Bearingcomponents (rockers, rollers, sliding plates, pads, pins, nuts, washers, cotter pins, etc.) may have minorwear or deterioration, but remain in proper position. Longitudinal alignment is within design limits and isappropriate for the current temperature. Lateral restraint/guide systems (if present) are functioning asintended - there is no notable lateral misalignment. Paint system may have some deterioration - corrosionmay be present, but any section loss is incidental. Supporting steel superstructure may have minordeterioration.

Condition State 3: Steel hinge bearing assembly has moderate deterioration, but is still functioning asintended. Debris or corrosion may have resulted in a slight restriction of movement (cleaning and/orlubrication may be recommended). Primary bearing components (rockers, rollers, sliding plates,elastomeric pads, pins, etc.) may have moderate wear (or deterioration), or slight misalignment.Secondary bearing components (bolts, nuts, washers, spacers, guides, cotter pins, etc.) may be loose ormissing. Longitudinal alignment may be near the design limits, or may be somewhat inappropriate for thecurrent temperature. Lateral restraint/guide systems may be worn, loose, or slightly binding - there maybe slight lateral misalignment. Paint system may have extensive deterioration - surface corrosion may beprevalent (notable section loss may be present). Supporting steel superstructure may have moderatedeterioration.

Condition State 4: Steel hinge bearing assembly has extensive deterioration - bearing function may beimpaired, but the load-carrying capacity has not been significantly reduced. Debris or corrosion may berestricting movement (cleaning and/or lubrication may be required). Primary bearing components(rockers, rollers, sliding plates, elastomeric pads, pins, etc.) may have extensive wear (or deterioration), ormay be misaligned. Longitudinal alignment may be at the design limits (contacting or binding), or may becompletely inappropriate for the current temperature. Lateral restraint/guide systems may have failed, orthere may be excessive lateral misalignment. Paint system may have failed - there may be extensivecorrosion, with significant section loss. Supporting steel superstructure may have extensive deterioration.

Condition State 5: Steel hinge bearing assembly has severe or critical deterioration. The load-carryingcapacity has been significantly reduced - structural analysis or immediate repairs may be required.Bearing movement may be completely restricted (primary bearing components may be frozen, binding, orseverely out of alignment.). Longitudinal or lateral misalignment may have resulted in significant loss ofbearing area. There may be severe section loss. Supporting steel superstructure may have severe orcritical deterioration.


Element #379: Concrete Hinge Assembly

This element applies to hinge bearing assemblies on concrete box girders (or other concrete bridges). Thisincludes hinge bearing assemblies of any type (rocker, roller, sliding plate, or elastomeric pad), andincludes both expansion and fixed hinge bearing assemblies. While this element typically refers tocantilever hinges on concrete box girders, it can be used to rate any bearing assembly where a concretesuperstructure element bears upon another concrete superstructure element. This is an “each” item, asingle condition state must be determined for each hinge assembly (if the quantity of individual bearingscannot be determined, the entire hinge joint can be rated as one unit).

Condition State 1: Concrete hinge bearing assembly has little or no deterioration. There may be minordebris, but there is no restriction of movement - lubrication system (if present) is functioning properly.All bearing components (rockers, rollers, sliding plates, pads, pins, nuts, washers, cotter pins, etc.) are ingood condition. Longitudinal alignment is within design limits and is appropriate for the currenttemperature. Lateral restraint/guide systems (if present) are functioning as intended - there is no notablelateral misalignment. Supporting concrete superstructure may have minor cracking or staining, but thereare no delaminations, spalls, or repair patches.

Condition State 2: Concrete hinge bearing assembly minor to moderate deterioration, but is stillfunctioning as intended. Debris or corrosion may have resulted in a slight restriction of movement(cleaning and/or lubrication may be recommended). Primary bearing components (rockers, rollers, slidingplates, elastomeric pads, pins, etc.) may have moderate wear, moderate deterioration, or slightmisalignment. Secondary bearing components (bolts, nuts, washers, spacers, guides, cotter pins, etc.) maybe loose or missing. Longitudinal alignment may be near the design limits, or may be somewhatinappropriate for the current temperature. Lateral restraint/guide systems may be worn or loose - theremay be slight lateral misalignment. Supporting concrete superstructure may have moderate cracking,scaling, leaching, or staining. There may be some delamination & spalling - but any exposure ofreinforcement or tensioning steel is limited. Patched areas (if any) remain sound.

Condition State 3: Concrete hinge bearing assembly has extensive deterioration - the function may beimpaired, but the load-carrying capacity has not been significantly reduced. Debris or corrosion may berestricting movement (cleaning and/or lubrication may be required). Primary bearing components(rockers, rollers, sliding plates, elastomeric pads, pins, etc.) may have extensive wear, extensivedeterioration, or significant misalignment. Longitudinal alignment may be at the design limits (contactingor binding), or may be completely inappropriate for the current temperature. Lateral restraint/guidesystems may have failed, or there may be excessive lateral misalignment. Supporting concretesuperstructure may have extensive scale, cracking, leaching, or rust/water staining. There may besignificant delamination & spalling (exposed reinforcement or tensioning system may have some sectionloss). Structural cracks (shear or flexure) may be present.

Condition State 4: Concrete hinge bearing assembly has severe or critical deterioration. The load-carrying capacity has been significantly reduced - structural analysis or immediate repairs may berequired. Bearing movement may be completely restricted (primary bearing components may be frozen,binding, or severely out of alignment.). Longitudinal or lateral misalignment may have resulted insignificant loss of bearing area. Supporting concrete superstructure may have severe structural cracking orspalling (exposed reinforcement or tensioning system may have significant section loss).


3.5.4 Steel Cables

Steel cables are used in suspension bridges, cable-stayed bridges, and tied arch bridges. The rating shouldtake into consideration both the condition of the cable, as well as the condition of the cable anchorage.

Element #146: Steel Cable - Uncoated

This element applies to bare steel cables (such as suspension, hanger, or tie cables) that serve as a primarystructural element on a bridge. The quantity is expressed as an each item.

Condition State 1: Steel cable (including cable anchorages) has little or no corrosion.

Condition State 2: Steel cable may have moderate surface corrosion (no section loss). Cable banding isintact. Cable anchorages have no evidence of distress.

Condition State 3: Steel cable may extensive surface corrosion, but any section loss is incidental (theload carrying capacity has not been reduced). There may be minor wear or abrasion at contact points.Cable banding may have started to loosen. Cable anchorages may show evidence of loosening or slightslippage.

Condition State 4: Steel cable may have advanced corrosion (significant section loss). The load carryingcapacity has been reduced - structural analysis or immediate repairs may be required. Cable may havesevere wear or abrasion at contact points. Cable banding may have failed - cable strands may be loose orbroken. Cable anchorages may have significant slippage.

Element #147: Steel Cable - Coated or Encased

This element applies to coated steel cables (such as suspension, hanger, or tie cables) that serve as astructural element on a bridge. This can include cables that are painted, galvanized, covered with aprotective sheathing, or encased in a conduit. The quantity is expressed as an each item.

Condition State 1: Cable coating (or encasement) is sound and functioning as intended to protect thecable (and cable anchorages) - there is no corrosion.

Condition State 2: Cable coating (or encasement) may have minor deterioration (peeling, cracking,fading, etc.) - surface corrosion may have formed.

Condition State 3: Cable coating (or encasement) has moderate deterioration - surface corrosion may beprevalent, but there is no section loss. Cable may have minor wear or abrasion at contact points. Cableanchorages have no evidence of distress.

Condition State 4: Cable coating (or encasement) has extensive deterioration. There may be extensivesurface corrosion, but any section loss is incidental (the load carrying capacity has not been reduced).There may be minor wear or abrasion at contact points. Cable banding may have started to loosen. Cableanchorages may show evidence of loosening or slight slippage.

Condition State 5: Coated steel cable may have advanced corrosion (significant section loss). The loadcarrying capacity has been reduced - structural analysis or immediate repairs may be required. Cable mayhave severe wear or abrasion at contact points. Cable banding may have failed - cable strands may beloose or broken. Cable anchorages may have significant slippage.


3.5.5 Secondary Structural Elements

Element #380: Secondary Structural Elements

This element applies to any type of secondary structural element. This can include superstructuremembers such as diaphragms, lateral bracing, struts, truss portal & sway bracing, or shear keys. This caninclude substructure elements such as pier crash struts or cross bracing. This can include specializedelements on movable spans (such as sheaves, trunnions, turntables, or counterweights). This includes anymaterial (or combination of materials). The quantity is expressed as an each item - the quantity can belisted as “1” (it isn’t necessary to count the total number of secondary elements on a bridge).

Condition State 1: Secondary elements have little or no deterioration. Steel members have little or nocorrosion - the paint system (if present) is sound & functioning. Concrete members may have minorcracking. Timber members may have minor cracking or splitting. All connections are sound (no evidenceof distress).

Condition State 2: Secondary elements have minor to moderate deterioration. Steel members may havemoderate paint failure or surface rust - there may be minor flaking or pack rust, but only minimal sectionloss. Concrete surfaces may have moderate staining, scale, cracking, or leaching - there may be minordelaminations & spalls, but there is minimal exposure of reinforcement. Timber members may havemoderate cracks, splits, checks, decay, or fire damage - but there is no evidence of structural distress(crushing or sagging). Connections may show have minor distress. There may be minor impact damage(minor gouges, spalls, or scrapes), but there is no significant out of plane bending. The element may havebeen repaired, or had some sections replaced. Any patched, spliced, or reinforced areas are sound.

Condition State 3: Secondary elements have extensive deterioration, but the element is still functioningas intended. Steel members & connections may have extensive corrosion, with measurable section loss.Concrete surfaces may have extensive scale, cracking, or leaching/rust staining. Delamination & spallingmay be prevalent (exposed rebar may have measurable section loss). Timber members may haveextensive splits, checks, decay, or fire damage - there may be some sagging or crushing. There may bemoderate traffic impact damage (significant cracking or spalling) - the member may be bent out of plane.Repaired or reinforced areas may have been re-damaged or began to deteriorate. Connections may beloosening.

Condition State 4: Secondary elements have severe damage deterioration. Element is no longerfunctioning as intended - structural analysis or immediate repairs may be required. Steel members &connections may have advanced corrosion, with severe section loss. There may be significant fatiguecracks. Concrete surfaces may have severe structural cracking or extensive spalling (exposed rebar mayhave severe section loss). Timber members may have severe structural cracking, sagging, or advanceddecay. There may be severe traffic impact damage - members may be severed or bent severely out ofplane, connections may have been torn loose. Connections may have failed.


3.5.6 Cast-in-Place (CIP) Piling

Element #382 (Cast-in-Place Piling): This element applies to steel shell piling (typically cylindricalin cross-section) that are filled with concrete after being driven. The quantity is expressed as an each item.

Condition State 1: CIP piling has little or no deterioration. Paint system (if present) remains sound. Thesteel shell may have minor staining or corrosion, but there is no section loss. There is no notable marinegrowth. Piling is relatively straight and properly positioned.

Condition State 2: CIP piling has minor to moderate deterioration. Paint system (if present) may havemoderate deterioration. The steel shell may have moderate surface corrosion, but any section loss isminor. Marine growth may be present. Piling may be slightly bowed, bent, or out of position.

Condition State 3: CIP piling has extensive deterioration, but the load-carrying capacity has not beensignificantly reduced. Paint system may have failed. The steel shell may have extensive flaking rust (withsignificant section loss), but there is no exposure of the concrete fill. There may be extensive marinegrowth. Piling may be significantly bowed, bent, or out of position.

Condition State 4: CIP Piling has severe or critical deterioration. The load-carrying capacity of the pilinghas been significantly reduced - immediate repairs or structural analysis may be required. The steel shellmay have advanced corrosion (with severe section loss) - the concrete fill may be exposed. Piling may beseverely bowed, bent, or out of position.

3.5.7 Tunnels

Element #381 (Tunnels): This element applies to roadway tunnels of any type or material. This elementincludes tunnels constructed by boring, blasting, or by “cut and fill”. Tunnels are typically constructed of(or lined with) reinforced concrete - exposed surfaces often protected with tile. The quantity is expressedas a “linear ft.” item and is rated on a scale of 1-4.

Condition State 1: Tunnel has little or no deterioration. Tiles surfaces are sound (there may be minorscrapes, staining, or discoloration). Concrete surfaces may have minor cracking, scaling, or leaching(there are no notable delaminations or spalls). Joints have no notable leakage, separation, offset, ormisalignment.

Condition State 2: Tunnel has minor to moderate deterioration. Tile surfaces may have moderatestaining, discoloration, or deterioration - some tiles may be cracked, delaminated, loose, or missing.Concrete surfaces may have moderate cracking, scaling, or leaching. There may be minor delamination orspalling - any exposure of reinforcement is minimal. Joints may have minor leakage, separation, offset, ormisalignment (there is no notable backfill infiltration).

Condition State 3: Tunnel has extensive deterioration, but the function or structural capacity of thetunnel has not been significantly impaired. Tile surfaces may have extensive deterioration - numeroustiles may be cracked, delaminated, loose, or missing. Concrete surfaces may have extensive cracking,scaling, or leaching. There may be significant structural cracking. Delamination or spalling may beprevalent (exposed rebar may have measurable section loss). Joints may have significant leakage,separation, offset, or misalignment (there may be minor backfill infiltration).

Condition State 4: Tunnel has severe or critical deterioration. The function or structural capacity of thetunnel has been severely impacted - immediate repairs or structural analysis may be required. Tilesurfaces may have complete failure (the majority of tiles are missing). Concrete surfaces may have severescaling or spalling (exposed reinforcement may have significant section loss). There may be severestructural cracking. Joints may have failed - there may be severe leakage, separation, offset, ormisalignment (there may be significant backfill infiltration).


3.6 Culvert Structural Elements

3.6.1 Inspection Procedures for Culverts

While the FHWA requires inspection of any structure with a total length of 20 ft. or greater, MinnesotaState law requires inspection of any structure with a total length of 10 ft. or greater - thus, the MnDOTstructure inventory includes many small (10-20 ft.) culverts.

While culverts are typically designed to allow drainage below a roadway embankment, they may alsoserve as underpasses for vehicles, pedestrians, or livestock. Culverts are designed to support the dead loadof the embankment material as well as live loads from traffic. If the embankment fill is more than 3 ft.deep, the fill is likely the primary load.

Culverts are constructed of a variety of materials, including concrete (cast-in-place or precast), corrugatedsteel plate, stone masonry, timber, or aluminum. The size and shape of a culvert is usually determined bythe hydraulic requirements (the opening must be large enough to carry the design discharge). Culvertshapes include arch culverts, box culverts, round pipe culverts, pipe-arch culverts, or elliptical culverts. Aculvert may consist of a single barrel or multiple barrels.

Culverts can be structurally classified as either “flexible” or “rigid”. Steel culverts are typicallyconsidered to be flexible - a flexible culvert derives a significant amount of structural strength from thesurrounding soil (the lateral soil pressure helps to resist vertical loads). Concrete culverts are typicallyconsidered to be rigid - a rigid culvert provides its own structural strength, and does not necessarilyrequire embankment fill.

A complete culvert inspection should include examining the culvert barrel, end treatments, waterway,embankment slopes, and the roadway. Ideally, a walk-through inspection of the entire the culvert barrelshould be conducted during low water conditions (high water or ice can prevent inspection of criticalareas). If an adequate walk-through inspection cannot be performed, it should be noted in the inspectionreport, and a complete inspection should be performed when conditions allow. If necessary, anunderwater inspection may need to be performed.

During culvert inspection, two main items need to be determined - the hydraulic performance and thestructural condition…

Hydraulic Performance: Poor hydraulic performance can result in excessive ponding, flooding ofadjacent properties, or washouts of the embankment and roadway. The inspector should note anyconditions that might reduce the hydraulic performance of the culvert.

Poor horizontal or vertical channel alignment can reduce hydraulic efficiency, increasesedimentation, or accelerate embankment erosion. Culverts on flat grades may have excessivesediment, culverts on steep grades may have outlet scour.

Accumulation of debris at the inlet (or excessive sedimentation within the barrel) can reduce theculvert's hydraulic capacity, accelerate embankment erosion, or alter the channel alignment.While some sedimentation is inevitable, any excessive sedimentation should be noted.

Changes in land use such as wetland drainage, deforestation, or increased development cansignificantly increase the runoff (and resultant discharge) that a culvert must carry. Channelchanges upstream (or immediately downstream) of the culvert can result in overtopping of theroadway. The inspector should note the high water elevation (or freeboard), as well as anyevidence of overtopping.


Structural Condition: Although culverts generally deteriorate at a slower rate than bridges, poorstructural condition can eventually result in load restrictions or failure. The inspector should note anyevidence of structural deterioration or distress - this includes material deterioration, barrel shape, and jointmisalignment/separation. Photographs are useful for comparison to previous (or future) inspections.

Material Deterioration: The inspector should inspect all visible surfaces of the culvert, and note both theextent and severity of any significant material deterioration.

Concrete culverts should be examined for scaling, cracking, leaching, rust stains, delaminations,or spalls. Severe cracking may indicate uneven settlement or structural overloading (from trafficor excessive earth pressure). Any significant spalling (with exposed reinforcing steel) should bedocumented. Connection bolts on pre-cast concrete culverts should be examined for corrosion.

Steel culverts should be examined for corrosion (particularly along the waterline). Bolted seamsshould be examined for cusping, loose or missing bolts, and cracking around bolt holes.

Timber culverts should be examined for weathering, warping, decay, fire damage, insect damage,or loose connections. Defects or connections can provide openings for moisture (and eventuallydecay) - any evidence of decay (such as fruiting bodies, staining, or surface depressions) shouldbe noted.

Masonry culverts should be examined for weathering, cracks, spalls, crushing, or misalignment ofthe masonry blocks. The mortar joints should be examined for any deterioration.

Aluminum culverts are relatively resistant to corrosion, but will corrode rapidly in highly alkalineenvironments. Bolted seams should be checked with a torque wrench (125 ft-lbs to 150 ft-lbs).

Barrel Shape: As flexible culverts (steel, aluminum, or timber) rely upon the surrounding soil to providelateral support, embankment stability is essential. Deflection or distortion of the barrel may indicateinstability of the supporting soil, and may reduce the load-carrying capacity of the culvert. Significantchanges in the barrel shape should be noted (and verified with field measurements).

Deflection is caused differential long-term settlement over the length of the culvert (fromembankment pressure). As the center of the embankment will settle more than the side slopes,culverts often end up with a low spot below the center of the roadway (steel culverts are oftendesigned with a camber to compensate for this).

Distortion is any deviation from the design cross-section of the culvert barrel, which should besymmetrical, with even curvature. Barrel distortion may be caused by uneven settlement,overloading, or from damage during the initial backfilling. Distortion is more common onculverts with less than 3 ft. of embankment fill.

Joint Misalignment & Separation: Joint misalignment or separation may be caused by improperinstallation, undermining, uneven settlement, or embankment failure. Leaking joints (exfiltration orinfiltration) can eventually result in severe undermining or even culvert failure.

Exfiltration is water leaking out of the culvert barrel - this can lead to “piping” (water flowingalong the outside of the culvert barrel), which can eventually erode the supporting soil. Theinspector should look for leaking joints and observe the culvert ends for evidence of piping.

Infiltration is water leaking into the culvert - this can also erode the supporting soil. Infiltrationcan be difficult to detect, as the backfill deposits are often washed away. The inspector shouldlook for staining at the joints on the sides and top of the culvert, or depressions above the culvert.


3.6.2 Condition Rating Guidelines for Culverts

Like bridges, culverts must be rated using both the NBI and structural element condition ratings…

NBI Condition & Appraisal Ratings: The overall structural condition of a culvert should be rated usingthe NBI Culvert Rating (FHWA Item #62 - see Section 2.1.5). The NBI condition ratings for deck,superstructure, and substructure (FHWA Items #58, 59, and 60) should all be listed as “N”.

If the culvert is designed to carry water (even when the channel running through the culvert is normallydry), the channel should be rated using NBI Channel & Channel Protection Condition Rating (FHWAItem #61- see Section 2.1.4). This rating should reflect the channel alignment, as well as the presence ofany sedimentation or debris. Note: If FHWA Item #61 is rated, the Waterway Adequacy Appraisal Rating(FHWA Item #71- see Section 2.2.1) must also be rated - this rating is primarily based upon the frequencyof overtopping of the roadway during high water events.

Structural Element Condition Ratings: The condition of the culvert barrel should be rated using one ofthe four AASHTO CoRe Elements (depending upon the material type). The quantity is expressed in linearfeet, as measured along the length of the barrel (multiplied by the number of barrels). If the conditionvaries along the length of the culvert barrel, more than one condition state may be used (all culvert barrelelements are rated on a scale of 1-4).

Element #240 - Steel Culvert (LF) Element #241 - Concrete Culvert (LF) Element #242 - Timber Culvert (LF) Element #243 - Masonry, Combination, or Other Material Culvert (LF)

MnDOT has added Element #388 to rate the condition of the headwalls, wingwalls, and aprons (or anyother type of culvert end treatment), and has added Element #421 to rate the condition of culvert footings.

The condition of the roadway above the culvert should be rated using Element #987 (roadway overculvert). The inspector should note any settlement or cracking of the roadway, as this may indicate culvertdistortion (or voiding of backfill). On flexible (steel) culverts; look for settlement above the centerline ofthe culvert. On rigid (concrete) culverts, look for settlement along the edges of the culvert. If applicable,the inspector should also rate Element #981 (signing) and Element #982 (approach guardrail).

The condition of the culvert embankment slopes should be rated using Element #985 (slopes & slopeprotection) - embankment erosion may be the result of channel scour or roadway drainage. If scour ispresent, Element #361 (scour smart flag) should be also be rated, if slope erosion is due to roadwaydrainage, Element #984 (deck & approach drainage) should also be rated.

Related Structure Inventory Items: The MnDOT structure inventory includes three culvert items - theculvert type, the culvert barrel length, and the culvert fill depth. The culvert type item describes theculvert material, barrel dimensions, and number of barrels. The culvert barrel length item indicates theculvert barrel length (to the nearest foot) as measured along the centerline of the culvert. These twoinventory items should correlate with the structural elements selected for the culvert.

The culvert fill depth item indicates the total depth of fill material (including the wearing surface, if any)that is supported by the culvert. This item is displayed to feet (rounded to the hundreds of a foot). Theinspector should note the culvert fill depth on the inspection report, as this may affect the load-carryingcapacity of the culvert. For example, if the roadway has been widened (and the culvert extended), theembankment depth may increase significantly.


3.6.3 Steel Culvert (Element #240)

This element applies to steel culverts of any type or shape.

Condition State 1: Steel culvert has little or no deterioration. The barrel has no deflection or distortion.The protective coating (if any) is sound. There may be minor staining or surface corrosion, but there is nosection loss. All seams and joints are sound - there is no distress or leakage.

Condition State 2: Steel culvert has minor to moderate deterioration. The barrel may have slightdeflection or distortion. The protective coating (if any) may have moderate deterioration. There may bemoderate surface corrosion or minor section loss (surface pitting). Bolted seams may have minor distress,but all bolts are secured, and there is no cracking around the bolt holes. Joints may have minor leakage,but there is no backfill infiltration.

Condition State 3: Steel culvert has extensive deterioration, but the function or structural capacity of theculvert has not been significantly impaired. The barrel may have measurable deflection or distortion(sagging, flattening, or buckling). The protective coating may have failed. There may be extensive surfacecorrosion or measurable section loss. Bolted seams may have obvious distress (seams may be cusped orcocked). Bolts may be loose or misaligned - cracks may have formed around the bolt holes. Joints mayhave moderate leakage - there may be minor backfill infiltration.

Condition State 4: Steel culvert has severe or critical deterioration. The function or structural capacity ofthe culvert has been severely impacted - immediate repairs or structural analysis may be required. Thebarrel may have severe deflection or distortion (sagging, buckling, or crown reversal). There may beadvanced corrosion & severe section loss (large sections rusted through). Bolted seams may have failed.Joints may have severe leakage or separation - there may be significant backfill infiltration.

3.6.4 Concrete Culvert (Element #241)

This element applies to reinforced concrete culverts (pre-cast or cast-in-place) of any type or shape.

Condition State 1: Concrete culvert has little or no deterioration. There may be minor cracking, scaling,leaching, or staining (there are no delaminations or spalls). Joints have no leakage, separation, offset, ormisalignment. Connection bolts (if any) may have minor surface corrosion.

Condition State 2: Concrete culvert has minor to moderate deterioration. There may be moderatecracking, scaling, leaching, or staining. There may be minor delamination or spalling - but any exposureof reinforcement is minimal. Joints may have minor leakage, separation, offset, or misalignment (there isno backfill infiltration). Connection bolts may have moderate corrosion.

Condition State 3: Concrete culvert has extensive deterioration, but the function or structural capacity ofthe culvert has not been significantly impaired. There may be extensive cracking, scaling, leaching orstaining. Structural cracking may be present. Delamination & spalling may be prevalent (exposed rebarmay have section loss). Joints may have moderate leakage, separation, offset, or misalignment (there maybe minor backfill infiltration). Connection bolts may have severe corrosion (or other distress).

Condition State 4: Concrete culvert has severe or critical deterioration. The function or structuralcapacity of the culvert has been severely impacted - immediate repairs or structural analysis may berequired. There may be severe structural cracking. There may be severe scaling or spalling (exposedreinforcement may have significant section loss). Joints may have severe leakage, separation, offset, ormisalignment (there may be significant backfill infiltration). Connection bolts may have failed.


3.6.5 Timber Culvert (Element #242)

This element applies to timber culverts of any type or shape (typically box culverts).

Condition State 1: Timber culvert has little or no deterioration. The barrel has no distortion or deflection.There may be minor weathering, splitting, cracking, or staining. There is no decay, fire damage, structuraldistress, or leakage. Connections are secure, members are properly aligned.

Condition State 2: Timber culvert has minor to moderate deterioration. Barrel may have slight deflectionor distortion. There may be moderate weathering, cracking, or splitting. There may be minor decay, firedamage, or structural distress. There may be minor leakage, but there is no backfill infiltration.Connections may be slightly loose. Members may be slightly warped, separated, offset or misaligned.

Condition State 3: Timber culvert has extensive deterioration, but the function or structural capacity ofthe culvert has not been significantly impaired. Barrel may have measurable deflection or distortion.There may be extensive weathering, cracking, or splitting. There may be moderate decay, fire damage, orstructural distress (slight crushing or sagging). There may be moderate leakage (or evidence of backfillinfiltration). Connections may be loose. Members may be significantly warped, separated, offset ormisaligned.

Condition State 4: Timber culvert has severe or critical deterioration. The function or structural capacityof the culvert has been severely impacted - immediate repairs or structural analysis may be required.Barrel may have severe deflection or distortion. Timber members may have severe cracking, fire damage,or structural failure (significant crushing or sagging). There may be severe leakage or backfill infiltration.Connections may have failed. Members may be broken or missing.

3.6.6 Masonry, Other, or Combination Material Culvert (Element #243)

This element includes masonry arch culverts, aluminum box culverts, or any other culvert not adequatelydescribed by elements #240, #241, or #242.

Condition State 1: Culvert has little or no deterioration (barrel has no deflection or distortion). Masonrymay have minor weathering (mortar joints are sound). Concrete may have minor cracking or scale. Steelmay have surface corrosion. Aluminum has no corrosion. Joints have no leakage.

Condition State 2: Culvert has minor to moderate deterioration (barrel may have slight deflection ordistortion). Masonry may have moderate weathering or cracking (mortar joints may have minordeterioration). Concrete may have moderate scaling or cracking (minor delamination or spalling). Steelmay have moderate surface corrosion (minor surface pitting). Aluminum may have minor surfacecorrosion. Joints may have minor separation, misalignment, or leakage (no backfill infiltration).

Condition State 3: Culvert has extensive deterioration, but the function or structural capacity of theculvert has not been significantly impaired. Barrel may have measurable deflection or distortion. Masonrymay have weathering or cracking (mortar joints may have extensive deterioration). Concrete may haveextensive scaling, or cracking (delamination or spalling may be prevalent). Steel may have extensivecorrosion (measurable section loss). Aluminum may have prevalent surface corrosion (section loss maybe present). Joints may have significant separation, misalignment, or leakage (there may be evidence ofbackfill infiltration).

Condition State 4: Culvert has severe or critical deterioration. The function or structural capacity of theculvert has been severely impacted - immediate repairs or structural analysis may be required. Barrel mayhave severe deflection or distortion. Masonry may have severe weathering or spalling (mortar joints mayhave failed). Concrete may have severe cracking, scaling, or spalling. Steel may have advanced corrosion,(severe section loss). Aluminum may have measurable section loss. Joints may have severe misalignment,or leakage (significant backfill infiltration).


3.6.7 Culvert End Treatment (Element #388)

This element applies to culvert headwalls, wingwalls, aprons or other end treatments (any material). Thequantity is expressed as an “each” item - on a typical culvert, the quantity will be “2” (one for each end).

Condition State 1: Culvert end treatment has little or no deterioration. Timber may have minor splitting.Steel may have minor surface corrosion. Masonry may have minor weathering (mortar joints are sound).Concrete may have minor cracking or scale.

Condition State 2: Culvert end treatment has minor to moderate deterioration. Timber may havemoderate splitting (minor decay or fire damage). Steel may have moderate surface corrosion (minorsection loss). Masonry may have moderate weathering (mortar joints may have minor deterioration).Concrete may have moderate cracking or scaling (there may be minor delamination or spalling). Endtreatment may have slight undermining, settlement, misalignment, or separation.

Condition State 3: Culvert end treatment has extensive deterioration. Timber may have extensivesplitting - there may be significant decay or fire damage (slight sagging or crushing). Steel may haveextensive corrosion (measurable section loss). Masonry may have extensive weathering (mortar jointsmay have significant deterioration). Concrete may have extensive cracking or scaling (delamination orspalling may be prevalent). End treatment may have significant undermining, settlement, misalignment,or separation.

Condition State 4: Culvert end treatment has severe deterioration, the function or structural capacity ofthe culvert has been severely impacted - immediate repairs or structural analysis may be required. Timbermay have severe splitting or advanced decay (severe sagging or crushing). Steel may have advancedcorrosion (severe section loss). Masonry may have severe weathering (mortar joints may have failed).Concrete may have severe cracking, scaling, delamination, or spalling. End treatment may have severeundermining, settlement, misalignment, or separation.

3.6.8 Culvert Footing (Element #421)

This element applies to culvert footings (typically concrete or masonry footings on arch culverts). Thiselement allows the footings to be rated separately from the remainder of the culvert barrel - it should onlybe used when the footing is above the ground line (and visible for inspection). This is a “linear ft.” item(measured along the length of the culvert barrel). Note: Element #220 (Reinforced Concrete Footing)should not be used for culverts, as it is classified as a substructure element.

Condition State 1: Culvert footing has little or no deterioration. Concrete may have minor cracking,leaching, or scaling. Masonry may have minor weathering (mortar joints are sound).

Condition State 2: Culvert footing has minor to moderate deterioration. Concrete may have moderatecracking, scaling or leaching (there may be minor delamination or spalling). Masonry may have moderateweathering (mortar joints may have minor deterioration). There may be slight settlement or undermining.

Condition State 3: Culvert footing has extensive deterioration. Concrete may have extensive cracking,scaling or leaching (delamination or spalling may be prevalent). Masonry may have extensive weathering(mortar joints may have significant deterioration). There may be significant settlement or undermining.

Condition State 4: Culvert footing has severe or critical deterioration. The function or structural capacityof the culvert has been severely impacted - immediate repairs or structural analysis may be required.Concrete may have severe cracking, scaling, delamination, or spalling. Masonry may have severeweathering (mortar joints may have failed - masonry courses may have severe separation or offset). Theremay be severe settlement or undermining.


3.7 Smart Flag Elements

“Smart Flag” elements identify conditions or problems present on a bridge that are not adequatelyaddressed by conventional structural element language. Smart flags may refer to specific problems thatwarrant special attention or follow-up action, or may provide detailed information about the condition ofspecific bridge elements. MnDOT currently has twelve Smart Flag elements…

Element #356: Fatigue Cracking Smart Flag Element #357: Pack Rust Smart Flag Element #358: Deck Cracking Smart Flag Element #359: Underside of Conc. Deck Smart Flag Element #360: Substructure Settlement Smart Flag Element #361: Scour Smart Flag Element #362: Traffic Impact Smart Flag Element #363: Section Loss Smart Flag Element #964: Critical Finding Smart Flag Element #965: Shear Cracking Smart Flag Element #966: Fracture Critical Smart Flag Element #967: Gusset Plate Distortion Smart Flag

The quantity for Smart Flag elements should always be listed as “1”. Most Smart Flag elements are notautomatically displayed on the MnDOT Bridge Inspection Report - the inspector must determine whenthey should be added and rated. The exceptions are Smart Flag #964 (displayed for all bridges), SmartFlag #361 (displayed on all scour critical bridges), and Smart Flag #966 (displayed on all fracture criticalbridges).

3.7.1 Fatigue Cracking Smart Flag (Element #356)

This smart flag applies only to primary steel structural elements (typically superstructure elements) - itshould only be used if fatigue cracking is present (cracked tack welds should not be considered unlessthey have propagated into the base metal).

Condition State 1: Fatigue cracking has been arrested (drilled or ground out). Any resultant damage tothe steel element has been repaired (the element may still be fatigue prone).

Condition State 2: Fatigue cracking exists and has not been arrested. Note: this condition state isnormally used when fatigue cracking is initially observed, or when additional fatigue cracking isobserved (after repairs).

Condition State 3: Fatigue cracking has seriously damaged a steel bridge element. Immediate repairs orstructural analysis may be required.


3.7.2 Pack Rust Smart Flag (Element #357)

This smart flag only applies to primary steel structural elements (typically superstructure elements) - itshould only be used if pack rust is present. Pack rust is corrosion between adjacent steel surfaces thatresults in deformation due to the expansion of oxidized steel. Pack rust is commonly found on trussconnections, splice plates, and along the edge of built-up riveted members. Pack rust may eventuallyresult in the failure of pins, rivets, bolts, or welds. Note: pack rust typically indicates the presence ofsection loss.

Condition State 1: Pack rust has started to form on a steel element or connection (rust staining is evidentalong the edges or seams).

Condition State 2: Pack rust has started to distress a steel element or connection (there may be minorspreading, swelling, or scalloping).

Condition State 3: Pack rust has resulted in significant distress to a steel element or connection. Theremay be significant spreading, swelling, or scalloping - steel members may be significantly deformed ordistorted. However, all connectors (pins, rivets, or bolts) remain intact.

Condition State 4: Pack rust has resulted in severe distress to a steel element or connection. Immediaterepairs or structural analysis may be required. Steel members may be severely deformed or distorted, orconnectors (pins, rivets, or bolts) may have failed.

3.7.3 Concrete Deck Cracking Smart Flag (Element #358)

This smart flag is used to rate the extent and severity of cracking in concrete wearing surfaces - if thedeck has a bituminous or gravel wearing surface, there is no need to use this smart flag. Cracking of thewearing surface will eventually result in chloride contamination of the underlying concrete deck, andcorrosion of the reinforcing steel. This smart flag can be used to track preventative maintenance (cracksealing), which can increase the service life of the deck. The condition state language for this smart flag isbelow is based upon the following general definitions…

Crack Width: “insignificant cracks” are those too narrow to practically measure, “moderatecracks” are those large enough to measure, and “severe” cracks are those greater than ¼” in width(or otherwise deemed “severe” by the judgment of the inspector).

Crack Density: “minor” crack density is an approximate spacing of 10 ft. or greater, “moderate”density is a spacing of 5-10 ft., and “severe” density is a spacing of 5 ft. or less (or otherwise deemed“severe” by the judgment of the inspector).

Condition State 1: Cracks in the concrete wearing surface are sealed or insignificant in size and density.

Condition State 2: Concrete wearing surface has unsealed cracks of moderate size or density.

Condition State 3: Concrete wearing surface has unsealed cracks of moderate size and density.

Condition State 4: Concrete wearing surface has unsealed cracks of severe size and/or density.


3.7.4 Underside of Concrete Deck Smart Flag (Element #359)

This smart flag must be rated for all bridges with a concrete deck or slab (even if the underside of thedeck is concealed by stay-in-place forms). This smart flag should typically not be used for bridges with anintegral superstructure & deck (such as precast channels, prestressed tees, or prestressed voided slabs).

Note: “Distressed area” refers to the total area (on the underside of a concrete deck or slab) withleaching (efflorescence), salt/ water saturation, rust stains, delaminations, spalls, temporary repairpatches, or other significant deterioration. On decks with stay-in-place forms, areas with corrosion,leaching, or other significant deterioration should be considered to be “distressed”.

Condition State 1: Underside of the concrete deck (or slab) has little or no distress. There may be minorcracking or light leaching. Stay-in-place forms have no corrosion.

Condition State 2: The total “distressed area” on the underside of the concrete deck (or slab) is 2% orless of the total deck area.

Condition State 3: The total “distressed area” on the underside of the concrete deck (or slab) is morethan 2%, but not more than 10% of the total deck area.

Condition State 4: The total “distressed area” on the underside of the concrete deck (or slab) is morethan 10%, but not more than 25% of the total deck area. There may be impending full-depth deck failures- structural underpinning may be present (or required).

Condition State 5: The total “distressed area” on the underside of the concrete deck (or slab) is morethan 25% of the total deck area. There may be full-depth deck failures - structural underpinning may bepresent (or required).

3.7.5 Substructure Settlement & Movement Smart Flag (Element #360)

This smart flag only applies to bridge substructure elements (piers, abutments, or wingwalls) that showevidence of settlement, movement, or rotation. It is intended to identify bridges that are experiencingsettlement and to provide some measure of the magnitude of that settlement.

Condition State 1: Substructure elements have visible settlement, movement or rotation. The settlementhas been arrested, appears to have stabilized, or is minor.

Condition State 2: Substructure elements have continuing settlement, movement or rotation. If notarrested, this could adversely impact the structural integrity of the bridge.

Condition State 3: Substructure elements have severe settlement, movement or rotation - structuralanalysis may be warranted.


3.7.6 Scour Smart Flag (Element #361)

This smart flag is intended to identify bridges that are experiencing scour (or have a history of scourproblems) and to provide some measure of the magnitude of scour. This smart flag also identifies bridgesthat are scour critical, or require scour monitoring during high water events. Note: if the MnDOT ScourCode is listed as D, G, K, O, P, R or U, this smart flag will automatically be added. During each routineinspection, substructure components that are submerged in water should be investigated for scour bywading and probing. If the channel is too deep for wading, the underwater inspection report should bereviewed to determine the condition rating for this smart flag.

Condition State 1: Scour exists, but is of little concern to the structural integrity of the bridge. Note:bridges with a MnDOT Scour Code of D, G, K, O, P, R or U can be rated as condition 1, even if no scouris currently present at the bridge site.

Condition State 2: Scour exists that, if left unchecked, could adversely impact the structural integrity ofthe bridge.

Condition State 3: Scour exists that is significant enough to warrant analysis of the structure.

3.7.7 Traffic Impact Smart Flag (Element #362)

This smart flag applies to primary structural bridge elements (typically superstructure) that have trafficimpact damage. While this typically refers to damage from high loads, it can include impact damage fromother causes (flood debris, ice dams, etc.). The inspector should note any recent (or previously un-recorded) damage, and note any repairs. This smart flag should remain even after repairs have been madeto provide a history of impact damage to the structure. Note: This smart flag does not apply to damagedrailings or guardrail.

Condition State 1: Impact damage has been repaired (minor damage may be present). Steel membershave been straightened and/or reinforced. Concrete members have been patched (there is no exposedreinforcement or tensioning cables).

Condition State 2: Impact damage has occurred, but the structural integrity of the element (or bridge) hasnot been significantly reduced. Steel members may be bent out of plane. Concrete members may bespalled (exposed reinforcement or tensioning cables are still intact).

Condition State 3: Impact damage has occurred and the strength of the member is impaired. Analysis iswarranted to ascertain the serviceability of the bridge.


3.7.8 Section Loss Smart Flag (Element #363)

This smart flag only applies to primary steel bridge structural elements (typically superstructure elements)that have section loss due to corrosion. Section loss is typically expressed as a percentage of the totalcross-section area of the member (the percentages in the rating descriptions are included as a generalguideline). Note: the presence of flaking rust or pack rust indicates that at least some section loss ispresent.

Condition State 1: Steel element has minor section loss (less than 2% of the total cross-section area). Ifthe steel element has been recently repainted, any previously existing section loss has been reinforced (oris less than 5% of the total cross-section area).

Condition State 2: Steel element has moderate section loss (from 2% to 5% of the total cross-sectionarea). If the steel element has been recently repainted, any previously existing section loss is not severeenough to warrant structural analysis (less than 10% of the effective section).

Condition State 3: Steel element has significant section loss, but structural analysis is not yet warranted(section loss is less than 10% of the total cross-section area) or structural analysis has determined that theexisting section loss has not significantly reduced the structural integrity of the element.

Condition State 4: Steel element has severe section loss (more than 10% of the total cross-section area).The load-carrying capacity of the element has been significantly reduced - structural analysis orimmediate repairs may be required.

3.7.9 Critical Finding Smart Flag (Element #964)

This smart flag indicates if a critical finding was observed during the inspection. A critical finding (ordeficiency) is any structural condition that, if not promptly corrected, could result in collapse (or partialfailure) of the bridge. This does not include safety-related problems (such as damaged railings, guardrails,etc.) - while such hazards should be reported and addressed promptly, they are not expected to result incollapse of the bridge, and are not considered to be critical findings.

Note: this smart flag must be included and rated on all bridge inspection reports - MnDOT TechnicalMemorandum TM-05-02-B-02 outlines the reporting and follow-up procedures for a critical finding.

Condition State 1: No critical findings were observed during the inspection.

Condition State 2: A critical finding was observed during the inspection. The condition should bethoroughly documented, and the Engineer (and Bridge Owner) must be notified immediately. Itmay be necessary to restrict traffic until further evaluation can be made or until the situation iscorrected.


3.7.10 Concrete Shear Cracking Smart Flag (Element #965)

This smart flag only applies to bridges with reinforced concrete or pre-stressed concrete superstructureelements (beams, box girders, or slabs). Shear cracking can result from inadequate shear reinforcement,and typically appear as diagonal cracks near the supports (inclined towards the center of the span).

Condition State 1: No shear cracking is present.

Condition State 2: Minor shear cracking is present (for prestressed concrete, crack width is less than0.01”). Minor leaching or rust staining may be present along the cracks.

Condition State 3: Moderate shear cracking is present (for prestressed concrete, crack width is between0.01” and 0.025”). Extensive leaching or rust staining may be present along the cracks. However, thestructural integrity of the bridge has not been significantly reduced. Any severe shear cracks have beenrepaired and/or reinforced.

Condition State 4: Severe shear cracking is present (for prestressed concrete, crack width exceeds0.025”). Shear cracking may be severe enough to reduce the structural integrity of the bridge. Immediaterepairs or structural analysis may be required.

3.7.11 Fracture Critical Smart Flag (Element #966)

This smart flag identifies those bridges classified as “fracture critical”. The intent of this smart flag is toinsure that all fracture critical members are visually examined during each routine inspection, and toidentify problems discovered between “in-depth” inspections. Refer to the plans (or the fracture criticalreport) to identify the fracture critical members. Note: A “fracture critical” bridge has at least onefracture critical member (a steel tension member whose failure would be expected to result in collapse ofthe bridge). Only bridges carrying vehicular traffic are considered to be “fracture critical” (pedestrianand railroad bridges are excluded).

Condition State 1: Bridge is “fracture critical” - all fracture critical members are structurally sound (nosignificant damage or deterioration).

Condition State 2: Bridge is “fracture critical” - fracture critical member(s) have damage ordeterioration, but the members have either been repaired or structural analysis has determined that themember is stable for the anticipated loading (the bridge may have been posted with a load restriction).

Condition State 3: Bridge is “fracture critical” - damage or deterioration to fracture critical memberswarrants structural analysis or immediate repairs (or bridge has been closed to traffic).


3.7.12 Gusset Plate Distortion Smart Flag (Element #967)

This smart flag is intended to identify truss bridges (or open spandrel arch bridges) with gussetedconnections, and to indicate if any distortion (bending, bowing, or buckling) is evident on the gussetplates. This smart flag should be added and rated for any truss (or arch) bridge on which the primary trussmembers have gusseted connections. This smart flag does not apply to gusseted connections forsecondary members (such as lateral bracing members) that incorporate a gusseted connection.

Gusset plates should be examined with a straight edge for evidence of distortion (bending, bowing, orbuckling) - distortion should be measured and documented. Gusset plate distortion may result from anumber of factors including, but not limited to, structural loading, pack rust, or from initial construction(fit-up tolerances).

Condition State 1: Steel gusset plates have no distortion.

Condition State 2: Steel gusset plate(s) may have distortion (up to 1/8” along an un-reinforced freeedge*). Note: previously distorted gusset plates that have been reinforced should generally not be ratedabove Condition 2.

Condition State 3: Steel gusset plate(s) have distortion (up to 1/4” along an un-reinforced free edge*) -structural review or analysis may be warranted.

Condition State 4: Steel gusset plate(s) have distortion (more than 1/4” along an un-reinforced freeedge*) - structural review or analysis is warranted.

*The distortion limits outlined in these condition ratings are intended to be a general guideline - theEngineer could select a lower (or higher) rating depending upon the location, orientation, and nature ofthe distortion.


3.8 Other Bridge Elements

These elements were added by MnDOT to rate the condition of bridge items not addressed by the CoReelements. The quantity can be listed as “1 each”.

3.8.1 Signing (Element #981)

This element applies to any signing mounted on, or any signing related to the bridge. This can includeload posting signs, vertical or horizontal clearance signs, object (hazard) markers, speed limit signs, plowmarkers, advance warning signs, informational signs, changeable message signs, etc. Note: this elementwill be automatically added if the structure inventory indicates that signage is required. The actual loadposting (Tons) and/or posted vertical clearance (Feet/Inches) should be noted on the inspection report.

Condition State 1: All required signing is present and is in good condition (there may be minor damageor deterioration).

Condition State 2: All required signing is present - signs may have some damage or deterioration(slightly bent or faded), but remain readable.

Condition State 3: Signing (excluding vertical clearance or load posting signage) is absent, or existingsigning is damaged or deteriorated to the extent that repair or replacement is required.

Condition State 4: Required vertical clearance signing is absent, incorrect, or existing signing isdamaged or deteriorated to the extent that repair or replacement is required.

Condition State 5: Required load posting signing is absent, incorrect, or existing signing is damaged ordeteriorated to the extent that repair or replacement is required.

3.8.2 Approach Guardrail (Element #982)

This element rates the condition of in-place guardrail above or below the bridge. This includes all types ofguardrail (plate beam or cable), as well as guardrail end treatments and crash cushions/crash attenuators.

Condition State 1: All required guardrail is present, is in good condition, and is functioning as intendedto protect vehicles from impacting the bridge.

Condition State 2: Guardrail may have moderate damage or deterioration, but is still functioning asintended to protect vehicles from impacting the bridge.

Condition State 3: Guardrail has severe damage or deterioration - repair or replacement isrequired (possible traffic hazard).

3.8.3 Plowstraps (Element #983)

Plowstraps (or “plow fingers”) are small steel plates welded to expansion joints to prevent snowplowdamage to the joint - they are common on strip seal expansion joints.

Condition State 1: All required plowstraps are present.

Condition State 2: Some plowstraps are missing and need replacement.

Condition State 3: Most plowstraps are missing and need replacement.


3.8.4 Deck & Approach Drainage (Element #984)

This element rates the condition, function, and adequacy of the drainage system. This includes drainage ofthe deck and approaches, and can include areas adjacent to (or below) the bridge. This includes itemssuch as deck drains, inlets, scuppers, grates, drain troughs, downspouts, catch basins, spillways, splashaprons, ditches, or holding ponds. Note: downspouts should extend far enough to prevent runoff fromfalling onto the superstructure.

Condition State 1: Drainage system is in good condition and functioning as intended. There is no notableponding or drainage-related slope erosion.

Condition State 2: Drainage system is inadequate or is not functioning properly. The drainage systemmay be clogged with debris - flushing or cleaning may be required. There may be ponding on the deck,approaches, or below the bridge. Runoff may be contributing to slope erosion or deterioration of bridgeelements. Drainage components may be damaged or deteriorated, but remain intact.

Condition State 3: Drainage system has failed - repairs are required. Severe ponding may present atraffic hazard. Runoff may have resulted in severe slope erosion (or significant deterioration of bridgeelements). Drainage components may be disconnected, missing, or severely deteriorated.

3.8.5 Slopes & Slope Protection (Element #985)

This element rates the condition of the slopes and slope protection - this includes unprotected (bare dirt)slopes. This can include the slopes in front of abutments, abutment side slopes, slopes around piers, orculvert embankments. Slope protection may consist of concrete, bituminous-coated aggregate, looseriprap, grouted riprap, gabions, revet mattresses, or any material intended to protect the slope fromerosion. Note: slope erosion may be related to deck drainage or scour - the inspector should attempt todetermine the cause of any slope erosion.

Condition State 1: Slopes are in good condition - there is no notable erosion. Substructure is adequatelyprotected (no exposure of footings or pilings). Slope protection (if present) may have minor deterioration(there is no notable settlement, heaving, or undermining).

Condition State 2: Slopes may have minor to moderate erosion. Footings (or pilings) may be slightlyexposed, but there is no significant undermining or loss of backfill. Slope protection (if present) may havemoderate deterioration - there may be settlement, heaving, or undermining.

Condition State 3: Slopes may have severe erosion - repairs are required. Footings may be significantlyundermined - there may be significant loss of backfill. Slope protection (if present) may be severelydeteriorated - there may be significant settlement, heaving, or undermining.

3.8.6 Curb & Sidewalk (Element #986)

This element rates the condition of the sidewalk and curb on the bridge (or approaches). This generallydoes not apply to a sidewalk running below the bridge.

Condition State 1: Sidewalks and curbs are in good condition - there may be minor damage ordeterioration.

Condition State 2: Sidewalks and/or curbs have moderate damage or deterioration. Concrete may havecracking, spalling, or delamination. Timber may have cracking, splitting or decay.

Condition State 3: Sidewalks and/or curbs have severe damage or deterioration (repairs are required).


3.8.7 Roadway over Culvert (Element #987)

This element rates the condition of the roadway running above a culvert. Cracking or settlement of theroadway may be the result of culvert settlement, barrel distortion, or voiding of backfill. On flexible(steel) culverts; look for cracking and settlement above the centerline of the culvert. On rigid (concrete)culverts, look for cracking and settlement along the edges of the culvert. This element can also be used torate the condition of roadways on filled spandrel arch bridges or running through tunnels.

Condition State 1: Roadway above culvert is in good condition. The paving may have minor cracking,but there is no settlement.

Condition State 2: Roadway above culvert has moderate cracking (or other deterioration). There mayslight settlement.

Condition State 3: Roadway above culvert has severe cracking (or other deterioration) - there may besignificant settlement.

3.8.8 Miscellaneous Items (Element #988)

This element can be used to rate the condition of any bridge feature not adequately described by the otherelements (such as lighting or utilities). This element can also be used to address maintenance needs (suchas flushing, tree trimming or graffiti).

Condition State 1: Minor damage or deterioration.

Condition State 2: Moderate damage or deterioration.

Condition State 3: Severe damage or deterioration - repairs may be required.


Appendix A: Bridge Components & Structure Types

Note: This appendix is incomplete - it will eventually include general inspection procedures andcondition rating guidelines for common bridge superstructure type, this will essentially be a condensedversion of the guidelines in the Bridge Inspector’s Reference Manual (BIRM).

A.1 Substructure Components

This section includes general inspection procedures and condition rating guidelines for substructurecomponents (abutments, piers, and wingwalls). This includes general descriptions and terminology, aswell as guidelines for the proper selection of structural elements (and determining element quantities).

A.1.1 Condition Rating Procedures for Abutments

Components of a Concrete Abutment: Most abutments are constructed of reinforced concrete - whilethe overall configuration will vary, most concrete abutments share these typical components…

Stem: The abutment stem (or breast wall) is the primary component of the abutment - it transmitsthe load of the bridge superstructure to the footing, and retains the abutment backfill.

Bearing Seat: The bearing seat provides a horizontal bearing area for the superstructure.

Parapet: The parapet (or back wall) prevents backfill soil from sliding onto the bearing seat, andprovides support for the deck expansion joint (or approach slab).

Footing: The footing transmits the weight of the abutment, the soil loads, and the load of thebridge superstructure to the supporting soil. A footing may be supported by piling, or maytransfer these loads directly to the supporting soil or rock (“spread footing”).

Wingwall: A wingwall is typically a short retaining wall extending from each end of theabutment which is intended to retain the side slope. The wingwall configuration will varyaccording the height of the abutment and the site conditions.

Cross-section (side view) of a Typical Concrete Abutment

Abutment Backfill

Parapet (Back Wall)

Stem (Breast Wall)

Footing

Bearing Seat


Inspection Procedures for Concrete Abutments:

Note any concrete deterioration (cracking, leaching, rust staining, delamination or spalling). Note any evidence of deck joint leakage (such as staining on the abutment face or debris on the

bearing seat). Weep holes (typically located near the base of the stem) should be examined for proper function. Note any distress on the parapet (cracking, spalling or tipping) resulting from the superstructure

contacting the parapet or from approach pavement thrust. Note any evidence of settlement, rotation, or other movement. Note any deterioration of the slope protection, slope erosion, undermining, or footing/piling

exposure. If the abutment is submerged in water, probe along the front face for any evidence of scour

(review the underwater inspection report, if applicable).

Condition Rating Procedures for Concrete Abutments: An abutment has two basic functions - tosupport for the bridge superstructure, and to retain the abutment backfill. The condition ratings shouldreflect not only the condition of the visible concrete surfaces, but also the ability of the abutment toperform these two basic functions. The condition rating descriptions for reinforced concrete elements areoutlined in Section 3.4.3.

Element #215 (Reinforced Concrete Abutment) should be used to rate the abutment stem, seat,and parapet). This is a “linear foot” item - the quantity is determined by measuring horizontallyacross the front face of the abutment (excluding the wingwalls).

MnDOT has added element #387 (Reinforced Concrete Wingwall) to rate the wingwalls. This isan “each” item (a single condition state must be determined for each wingwall) - the quantity willtypically be “4” (one wingwall at each corner).

As the footings (and pilings) supporting a concrete abutment are typically not visible forinspection, they are typically not rated. If the abutment footing is visible for inspection, it can berated using element #220 (Reinforced Concrete Footing) - this is an “each” item.

If settlement, rotation, or other movement of the abutment is evident, the Settlement Smart Flag(element #360) must be rated accordingly (see Section 3.7.5). If scour is present, the Scour SmartFlag (element #361) must be rated accordingly (see Section 3.7.6).

Element #985 (Slopes & Slope Protection) should be used to rate the condition of the abutmentslopes (and slope protection, if any).

Abutment Backfill

Wingwall

Parapet

Footing

StemBearing Seat

Plan View of a Typical Concrete Abutment


Hollow Concrete Abutments: Hollow “U-Type” concrete abutments are actually an enclosed approachspan (typically a cast-in-place concrete T-girder or slab span). The wingwalls enclose the sides of thespan, creating a “hollow” abutment that appears to be solid (access hatches are typically located on thewingwalls or parapets). These are designed to reduce the dead load (as opposed to a solid abutment) andsubsequent settlement of the abutment. Note: periodic internal inspections are required to assess thecondition of the interior elements - confined space entry procedures may be required.

Element #215 (Reinforced Concrete Abutment) should be used to rate the front abutment stem (includingthe seat and parapet) as well as the rear abutment stem - the LF quantity will be twice that of conventionalabutment. Element #387 (Reinforced Concrete Wingwall) should be used to rate the condition of thesidewalls. An element must also be selected to rate the enclosed approach span - depending upon the spantype, this may include beam, deck, or slab elements.

Wingwall

FrontAbutment Stem

Front FootingStem

Rear Footing

Rear AbutmentStem

Embankment Fill

Elevation View of a Hollow Concrete Abutment

Section View (Looking Down) of a Hollow Concrete Abutment

FrontAbutment Stem

Front FootingStem

Rear AbutmentStem

Approach Span

Rear Footing


Condition Rating Procedures for Timber Abutments: Timber abutments are typically comprised ofthree main components (backfill planks, bearing cap, and piling), which are rated using separate structuralelements. These components may be connected with bolts, lag screws, nails, spikes, or drift pins (cap topiling connections are often reinforced with steel straps). The inspector should determine the condition ofeach element (see Section 3.4.5 for timber element rating descriptions), as well as the overall orientationand stability of the abutment. The presence of failed connections or misaligned members should bereflected in the element ratings. Note: If the abutment has tipped, rotated, or settled, the settlement smartflag (element #360) should be appropriately rated.

Backfill Planks: The backfill planks retain the abutment backfill and transfer the earth pressureforces to the piling - they should be inspected for bulging, gaps, or voided backfill. Element #216(Timber Abutment) should primarily reflect the condition of the backfill planks, but should alsoreflect the overall structural condition of the abutment. This is a linear ft. item (measured alongthe front face of the abutments (excluding the wingwalls).

Bearing Cap: The bearing cap provides a bearing seat for the superstructure, and transfers thesuperstructure loads to the piling. Element #235 (Timber Pier Cap) should be used to rate thecondition of the abutment bearing cap. This is a “linear ft.” item (measured along the length ofthe cap) - the total element quantity should include the pier caps (if any). Note: If the cap iscomprised another material (such as steel or concrete), the appropriate cap element should beselected.

Piling: The piling transmit the superstructure load to the supporting soil. To resist the horizontalforce resulting from earth pressure, abutment piling may incorporate steel cable tie-back systems.Element #228 (Timber Piling) should be used to rate the condition of the abutment piling. This isan “each” item - the total element quantity should include the pier piling (if any), but not thewingwall piling. Note: If the piling are comprised another material (such as steel or concrete),the appropriate piling element should be selected.

Wingwalls: MnDOT has added element #386 (Timber Wingwall) to rate the wingwalls, thequantity is expressed as an “each” item - on a typical bridge, this quantity will typically be “4”(one wingwall at each corner). The wingwall piling can be included in this element (there is noneed to include them in the total piling quantities).

Front View of a Typical Timber Abutment

Piling

Bearing Cap

Ground Line

Backing Planks


A.1.2 Condition Rating Procedures for Piers

Concrete Column Pier: The most common pier configuration is a reinforced concrete “column pier”,which is comprised of two or more columns (bearing on footings), which support a bearing cap. Thesepiers are typically cast-in-place, and are tied together with steel reinforcement to create a rigid frame.

Pier Cap: The pier cap is the upper horizontal portion of the pier that supports the superstructure- they are subjected to bending and shear forces. The pier cap (including the bearing seats) israted using element #234 (Reinforced Concrete Cap) - this is a “linear foot” quantity (measuredalong the length of the cap).

Pier Columns: The vertical pier columns transfer the superstructure load from the pier cap to thepier footing - they are primarily subjected to compression forces. Pier columns are rated usingelement #205 (Reinforced Concrete Column) - this is an “each” item, a single condition ratingmust be determined for each column. If there are protective crash struts (or barriers) between thepier columns, they can be rated using element #380 (Secondary Structural Elements) - this is an“each” item, the quantity can simply be left as “1” (there is no need to add them up them).

Pier Footings: As pier footings are typically below grade and not visible for inspection, they aretypically not rated.

Inspection Procedures for Concrete Piers:

Note any concrete deterioration (cracking, leaching, rust staining, delamination or spalling). Note any evidence of deck joint leakage (staining on the cap or debris on the bearing seat). Note any evidence of settlement, tipping, rotation, or other movement. If the pier is submerged in water, the perimeter of the pier should be probed for evidence of scour,

undermining, or footing/piling exposure (refer to the underwater inspection report, if applicable). Note the presence and condition of any pier protection components (such as dolphins, fenders, or

crash struts).

Pier Column

Typical Concrete “Column Pier” Configuration

Pier Cap

Bearing Seat

Pier Footing

Ground Line


Concrete Pier Walls: Another common reinforced concrete pier configuration is a “pier wall”, which issupported by a solid shaft (instead of separated columns) - the shaft may be straight (vertical) or tapered.Element #210 (Reinforced Concrete Pier Wall) should be used to rate any pier supporting element that is10 ft. or greater in width. This is a “linear ft.” quantity (measured horizontally along the face of the pierwall (on tapered pier walls, use the widest dimension).

A pier wall may or may not include a pier cap. If a pier cap is present, element #234 (Reinforced ConcreteCap) should be used to rate the cap and bearing seats. If no cap is present, the bearing seats can beincluded with element #210 (Reinforced Concrete Pier Wall). As pier footings are typically below gradeand not visible for inspection, they are typically not rated.

Concrete Pier Wall - Tapered Shaft without Pier Cap

Tapered Pier Wall

Footing

Bearing Seat

Ground Line

Pier Wall

Footing

Bearing Seat

Pier Cap

Concrete Pier Wall - Straight (Vertical) Shaft with Pier Cap

Ground Line


Hammerhead Pier: A “hammerhead pier” consists of a single column with a relatively wide cantileveredpier cap. Element #234 (Reinforced Concrete Cap) should be used to rate the cap and bearing pedestals -this is a “linear foot” quantity (measured along the length of the cap). The cantilever portion of the capshould be examined for any evidence of structural distress (such as shear cracking).

Element #205 (Reinforced Concrete Column) will typically be used to rate the column - this is an “each”item. However, if the vertical support is 10 ft. or greater in width, it should be rated using element #210(Reinforced Concrete Pier Wall) - this is a “linear foot” item. As pier footings are typically below gradeand not visible for inspection, they are typically not rated.

Pier Cap

Pier Column (or Pier Wall)

Pier Footing

Bearing Seat

Ground Line

Typical “Hammerhead” Pier Configuration


Pile Bent Piers: Piers comprised of two or more piling supporting a pier cap are known as pile bents -while these are typically comprised of timber, they may include steel or concrete members. The inspectorshould determine the condition of each element, as well as the overall orientation and stability of the pier.The presence of failed connections or misaligned members should be reflected in the element ratings.Note: If the pier has tipped, settled, or moved the settlement smart flag (element #360) should beappropriately rated.

Piling: Pier piling transmit the superstructure load from the pier cap to the supporting soil (they aremainly subjected to compression forces). Piling should be examined for impact damage or deterioration(particularly along the waterline or ground line). If the piling are submerged in water, the adjacent streambottom should be probed for evidence of scour (refer to the underwater inspection report, if applicable).MnDOT six piling elements - they are all “each” items, a single condition rating must be determined foreach pile.

Element #225: Unpainted (Weathering) Steel Piling Element #226: Prestressed Concrete Piling Element #227: Reinforced Concrete Piling Element #228: Timber Piling Element #382: CIP (Cast-in-place) Piling Element #419: Painted Steel Piling

Pier Cap: The pier cap provides a bearing seat for the superstructure, and transfers the superstructureloads to the piling. The connections between the cap and piling should be examined for any deteriorationor distress. On a pile bent pier, the cap will typically be rated using element #230 (Unpainted WeatheringSteel Pier Cap, element #231 (Painted Steel Pier Cap), element #234 (Reinforced Concrete Pier Cap), orelement #235 (Timber Pier Cap). These are linear ft. items (measured along the length of the cap) - thetotal element quantity should include the abutment bearing caps (if any).

Pier Bracing: To prevent buckling, timber pier pilings are often reinforced with diagonal bracing - theseshould be examined for deterioration, impact damage, or connection failure. Bracing members can berated using element #380 (Secondary Structural Elements) - this is an “each” item, the quantity cansimply be left as “1” (there is no need to count up the separate members).

Piling

Pier Cap

Ground Line

Pile Bent Pier

Diagonal Bracing


A.2 Superstructure Components

A.2.1 Condition Rating Procedures for Truss Connection Elements

MnDOT has created five elements to rate the condition of primary truss connections…

Element #423: Gusset Plate Truss Connection - Painted Steel Element #424: Gusset Plate Truss Connection - Weathering Steel Element #425: Pinned Truss Connection - Painted Steel Element #426: Pinned Truss Connection - Weathering Steel Element #967: Gusset Plate Distortion Smart Flag

A truss bridge is typically comprised of two parallel trusses - the locations where the truss membersconnect are referred to as “panel points” (they are usually numbered from the south or west). These trussconnection elements are all “each” items - each primary truss connection should be rated as a unit, thequantity should correspond with the number of truss panel points. For example, on a 5-panel truss bridgewith 6 panel points on the bottom chord and 4 on the top chord - the element quantity should be “20” (10for each truss). Note: For element #967 (Gusset Plate Smart Flag), the quantity should be listed as “1”.

Truss diagram for a 5-panel truss using a typical panel point numbering system

U1 U2 U3 U4

L0 L1 L2 L3 L4 L5

Gusset Plate Inspection & Rating Procedures

Truss connection gusset plates should be rated using element #423 (see section 3.4.1 for painted steelelements) or #424 (see section 3.4.2 for unpainted weathering steel elements). A gusseted trussconnection will typically include two main vertical gusset plates, but the condition rating may take intoconsideration any plates, angles, channels, or connectors (rivets, bolt, etc.) that make up the connection.Note: these elements should not be used for secondary members (such as lateral bracing members) thatincorporate a gusseted connection.

The gusset plate thickness indicated on the plans should be verified with field measurements. Gusset platetruss connections should be cleaned of debris to allow for a thorough examination of the gusset plates(and other members). Any significant section loss should be measured and documented. If a gusset platehas significant section loss along the edge of a connecting truss member, several measurements should berecorded along length of the connection to determine the average percent section loss along the crosssection. Ultrasonic thickness measurements are recommended for areas where only one side of a gussetplate is visible for inspection

Element #967 (Gusset Plate Distortion Smart Flag) should be added for all truss (or open spandrel arch)bridges with gusseted connections (see section 3.7.12). Gusset plates should be examined with a straightedge for any evidence of distortion (bending, bowing, or buckling) - any distortion should be measuredand documented. Gusset plate distortion may result from a number of factors including, but not limited to,structural loading, pack rust, or from initial construction (fit-up tolerances). If distortion is observed on atruss connection gusset plate, the findings should be reviewed by the program administrator (or a loadrating engineer) to determine the significance of the findings and to recommend any corrective actions.


Pinned Truss Connection Inspection Procedures

Pinned truss connections should be rated using element #425 (see section 3.4.1 for painted steel elements)or #426 (see section 3.4.2 for unpainted weathering steel elements). This element could also be used forprimary connections on open spandrel arch bridges, suspension bridges, or other pinned connections notcovered by element #160 (see section 3.5.2). Note: these elements should not be used for secondarymembers (such as lateral bracing members) that incorporate a pinned connection.

Pinned connections are common on truss bridges constructed prior to 1920. A pinned truss connectionwill typically have only one main pin - but the condition rating could take into consideration any nuts,spacers, plates, angles, channels, or connectors (rivets, bolts, etc.) that make up the connection.

Any significant section loss, pack rust, or misalignment should be documented. Pack rust is often presentat pinned connections on the truss bottom chord - this often results in section loss on the truss members,and can cause distress to the pinned connection. Eyebars should be examined for any separation orfractures along the forge lines. The floorbeam connections should also be examined. Periodic ultrasonicexamination of the main pins is recommended.

A.2.2 Measuring and Documenting Section Loss on Steel Members

Corrosion is the most common defect found on steel bridges - all corrosion results in at least some loss ofthe original steel cross-section - this is referred to as “section loss”. Accurately measuring anddocumenting the extent and location of section loss is one of the primary responsibilities of the bridgeinspector, and is essential in evaluating the load-carrying capacity of a steel bridge.

The bridge inspection report should accurately describe the location and extent of any significant sectionloss - section loss is typically expressed as a percentage of the original cross-sectional area.

On members subjected to axial loading (such as truss members), section loss is typicallyexpressed as percentage of the entire member cross-section. For example: “truss bottom chordmember L2-L3 has 15% section loss at the L2 connection”.

On members subjected to bending moment (such as girders or beams), section loss is typicallyexpressed as percentage of the bottom flange, top flange, or the web cross-section. For example:“the bottom flange of the west girder has 10% section loss at the 1st deck drain east of Pier #2”.

When describing section loss in an inspection report, it is important that the extent of section loss not bemisrepresented. For example, the bottom flange of a girder has a 1” diameter hole which constitutes 15%of the total bottom flange cross-section. While the flange has rusted completely through at the hole, thisshould not be described as “the bottom flange has 100% section loss”, but rather as “the bottom flangehas 15% section loss” (or “the bottom flange of a girder has a 1” diameter hole”).

If the original cross-section has not yet been determined, it may be better to describe the location anddimensions of the area with section loss. For example: Girder #3 has 4” wide by 2” high area of pitting(up to 1/8” deep) at the west abutment bearing”.

When should section loss measurements be performed? As a general rule, section loss measurementsshould be taken if the approximate section loss on a primary structural steel member exceeds 5% of thetotal member cross-section (or 5% of the flange or web cross-section). As it is not generally practical toaccurately measure and document every area of section loss on a bridge, some judgment must be used bythe inspector in prioritizing the locations where section loss measurements are taken. Highly stressedportions of the structure (such as the bottom flange near the center of a span) should be prioritized forsection loss measurements. If section loss is present at similar details throughout a bridge, measurementsshould be taken at locations that appear to have the most severe and/or extensive section loss.


Locations Where Section Loss is Likely on Bridges: The locations where corrosion (and section loss)will occur on a bridge are typically predictable - steel members exposed to salt spray or covered by debriswill typically have section loss. The exact locations will vary depending upon the structural configurationand features present on the bridge - locations where corrosion (and section loss) is likely to occur includethe following…

Structural members located below deck joints Bearing areas Areas below deck drains or adjacent to downspouts Areas located directly above traffic (exposed to salt spray) Horizontal surfaces, field splices, or other details that tend to accumulate debris Fascia girders, beams, or stringers will typically have more corrosion and section loss than

interior members - particularly along the exterior bottom flange On bridges with concrete decks, corrosion will tend to be localized (below deck joints or leaching

cracks) - on bridges with timber decks, corrosion may be widespread Through truss and pony truss bridges will typically have section loss along the bottom chord,

particularly at the panel point connections - section loss may be present on the truss members orgusset plates. Truss diagonal and vertical members will typically have corrosion at the railingconnections, at the curb level, and at the bottom chord connections

Steel box girders (or other box sections) will develop internal corrosion if moisture accumulateswithin the box section

Steel piling will typically have corrosion at the waterline and/or ground line

Cleaning Prior to Inspection: In order to properly inspect a steel member (and to determine the extent ofsection loss) - the steel must first be cleaned of any dirt, debris, or excess flaking rust. A large build-up ofdebris on a steel member indicates not only inadequate maintenance, but also indicates inadequateinspection. A bridge inspector should have ready access to cleaning tools such as a shovel, spade, whiskbroom, wire brush, pick hammer, or scraper. Inspection during (or immediately after) re-paintingcontracts will often allow for more precise section loss measurements.

Methods of Measurement: During a bridge inspection, initial section loss is often estimated (often aidedby a straight edge or ruler) - as section loss advances, more precise measurements may be necessary.Calipers are a simple and inexpensive method of measuring the thickness of the remaining steel, but theymay not be able to reach some locations (such as a girder web). An ultrasonic thickness gauge is the mostprecise and effective method of obtaining thickness measurements - this can be used in confined areas orlocations where only one side of the member is accessible.

Field Notes & Cross-Section Diagrams: Field notes should be thorough, concise, and readable - theyshould include not only the thickness measurements, but the exact location where those measurementswere taken. To determine the extent of section loss on a structural member, the original cross section areamust be known. If no plans are available, measurements and thickness readings should be taken in areaswithout section loss to establish a basis for the section loss calculations. Plan dimensions and thicknessesshould be verified.

Cross-section diagrams are helpful in documenting field measurements and performing section losscalculations. If possible, blank forms (with cross section diagrams) should be prepared prior to takingfield measurements. To facilitate section loss calculations, the exact location of all thickness readingsshould be recorded - areas with section loss should be clearly indicated.


Example of cross section diagram with section loss field measurements

Section Loss Calculations: When performing section loss calculations, the level of accuracy willgenerally depend on how many thickness measurements are taken - the more measurements are taken, thegreater the accuracy. One common method of calculating section loss is to simply take the average ofseveral thickness measurements over a portion of the member cross-section. A slightly more accuratemethod is to divide the cross-section into trapezoidal sub-areas, based upon the exact locations of thethickness measurements - these areas are then calculated separately and added up. Whatever method isused, it should be done clearly and consistently, so the calculations can be easily checked and verified.

Cross-section showing location of thicknessmeasurements

Trapezoidal sub-area


Appendix B: Bridge Load Capacity Ratings

B.1 General Load Rating Information

B.1.1 Load Ratings - Basic Requirements

A load rating refers to the calculations made to determine the safe live load carrying capacity of a bridgeand to provide a basis for posting and permit decisions. A load rating is calculated for a new bridge (usingthe bridge plans), and is re-calculated throughout the life of a bridge as changes occur (based uponinformation from inspections).

Any bridge (or culvert) on the MnDOT structure inventory which carries vehicular traffic must have aload capacity rating performed. A load rating report (along with any calculations) must be retained in thebridge owner’s files - a copy of the load rating report should be submitted to the MnDOT Bridge Office.

B.1.2 General Re-rating Guidelines

Section 6A.1.1 of the AASHTO Manual for Bridge Evaluation states that, as part of every inspectioncycle, bridge load ratings should be reviewed and updated to reflect any relevant changes in condition orloading noted during the inspection.

State of Minnesota Rule 8810.9500 (Subpart 2, Ratings) stipulates that a structure must be re-ratedwhen it is determined that a significant change has occurred in the condition of the structure. Ratings mustbe reviewed and the structure re-rated if necessary when the allowable legal load using the structure isincreased.

Section 15.6 of the MnDOT LRFD Bridge Design Manual states that a new bridge load rating shouldbe calculated whenever change occurs that would sufficiently change the rating. The most commonlyencountered types of changes are:

A modification that changes the dead load on the bridge (such as a deck overlay) Damage that alters the structural capacity of the bridge (such as being struck by an oversize load) Deterioration that alters the structural capacity of the bridge (such as corrosion or rot) Settlement, movement, or scour of a pier or abutment Repairs or remodeling. A change in the AASHTO rating specification. An upgrading of the rating software. A change in the laws regulating truck weights

B.2 Role of the Bridge Inspector (Load Ratings)

The information gathered during a bridge inspection (condition ratings, inventory information, andinspection notes) is essential in determining if there is a need for a new load capacity rating. A bridgeinspector should understand the basic principles of bridge load ratings, should be familiar with theMnDOT load rating forms, and should have access to the most recent load rating report for the structurebeing inspected.

Prior to performing an inspection, the bridge inspection report and structure inventory report should bereviewed to determine the following…

When was the last load rating performed? Is a load posting signage required?

During a bridge inspection, the inspector should determine (and report) the following…


Has any damage or deterioration occurred since the last load rating which is significant enough toreduce the load carrying capacity of the bridge?

Has any dead load been added to the bridge since the last load rating? Is the load posting signage (if required) in-place, correct, and readable?

The inspector should also note the presence of any salvaged steel components, temporary structuralsupports, or any other information that might affect the load carrying capacity of the structure. If theinspector suspects that a new load capacity rating is required, or that a review of the load rating may bewarranted - the Bridge Inspection Program Administrator should be promptly notified.

B.2.1 Documenting the Condition of Primary Structural Elements

Only those structural elements that are in the direct load path (from the vehicle down the supportingearth) affect the bridge load rating - this includes primary structural elements of the deck, superstructure,and substructure.

Deck deterioration may have an effect on the load-carrying capacity of a bridge. This may be aconcern on timber decks, slab spans, composite structures, or bridges with an integral deck andsuperstructure (such as cast-in-place concrete or prestressed T-beam bridges).

A superstructure component (girder, beam, arch, truss, floorbeam, stringer, etc.) will typically bethe controlling element in a load rating. Any significant damage or deterioration of a primarysuperstructure element will likely reduce the load-carrying capacity of the bridge.

The substructure (piers and abutments) should be examined for deterioration, as well as damagefrom ice flows or flood debris. Substructure components should be examined for any evidence ofinstability (settlement, tipping, misalignment, or undermining) that could affect the load-carryingcapacity of the bridge.

The bridge inspection report should document deterioration or damage on a primary structural element(direct load path element) with sufficient detail so that the load-carrying capacity of the member can bedetermined in a load rating analysis. On corroded steel members, deteriorated concrete members, ordecayed timber members, the loss in cross-sectional area should be determined as accurately asreasonably possible. Misaligned, bent, or kinked members should be measured and documented(particularly compression members). Distressed or deteriorated connections should be thoroughlydocumented. As the inspection notes alone may not be enough to convey this information, additionalmeasurements, sketches, or photographs may be required. By obtaining and documenting adequateinformation during the initial inspection, the need for a follow-up inspection may be avoided.

B.2.2 Identifying and Reporting Additional Dead Loads

The inspector should note any significant dead loads which have been added to the bridge since it wasconstructed. Any significant change in the dead load on a bridge should be promptly reported to theBridge Inspection Program Administrator.

Verify the deck wearing surface type, depth, and year of installation - this is a particular concernon bridges with bituminous or gravel wearing surfaces. Any discrepancies with the informationdisplayed on the structure inventory report should be noted, and brought to the attention of theInspection Program Administrator.

Have the original bridge railings been replaced, filled in, or otherwise modified? Have sign structures, light poles, or other ancillary structures or decorative features been installed

on the bridge? Have utilities (water mains, gas mains, etc.) been installed on the bridge? On culvert structures, the inspector should note any unusual deterioration or distortion below the

driving lanes (which may indicate the need to restrict heavy loads), and verify the embankmentfill depth displayed on the structure inventory report.


B.2.3 Verification of Load Posting Signage

During each inspection, the inspector must verify that load posting signage (if required) is in-place,correct, and readable (see section 2.2.7 for examples of load posting signs).

If a posting is required, the actual posting will be displayed on the header of the MnDOT BridgeInspection Report (load posting information is also displayed at the bottom right corner of the MnDOTStructure Inventory Report). If the load posting signs are missing, or do not correlate with theinspection report, the Inspection Program Administrator should be promptly notified.

The inspector should confirm that load posting signs are present either on or immediately in front of thebridge, and should note if advanced signs are present. All of these signs must display the correct weightlimits. The condition of load posting signage can be rated using element #981 (see section 3.8.1).

If it is apparent that load postings are not being adhered to, the Inspection Program Administrator shouldbe notified.

B.2.4 Verification of Member Sizes and Steel Type

The size of structural members (and the type of steel of which they are comprised) will have a significanteffect on the load-carrying capacity of the structure. While verification of the member sizes and steel typeis not typically within the scope of a routine bridge inspection, information observed and reported duringan inspection can be essential to performing accurate load ratings.

Field Measurements: On bridges without plans, load ratings are based upon field measurements - theload rating will only be as accurate as those field measurements. If possible, it is a good idea to note thesize, number, and spacing of structural members on the inspection report. This may help identify errors inthe load rating calculations. Prior to performing a new load rating, the size and spacing of the structuralmembers should be confirmed. Any discrepancies with plan dimensions, or the dimensions indicated onthe load rating calculations, should be promptly reported to the Inspection Program Administrator.

Salvaged Steel Members: The inspector should note if any observed conditions would suggest that thestructural steel members present on a bridge are older than the construction date listed on the structureinventory report. Over the years, steel trusses and beams have frequently been salvaged from an olderbridge and moved to a new location. In some cases, the age of the salvaged steel may not have beenconsidered in the existing load rating. Clues which might indicate the presence of salvaged steel includethe following…

A steel beam or steel truss bridge with a timber substructure Steel beams with variable depths or unequal spacing Steel members with different paint systems Beam ends that are laterally offset or overlapping at the piers Floorbeams that have been extended with welded field splices Connection holes or stiffeners in odd locations

The presence of salvaged structural members should be noted on the bridge inspection report. If the age ofsalvaged structural elements can be determined, it should be noted on the bridge inspection report. If theinspector suspects that the structural steel on the bridge is older that what was assumed in the load ratingcalculations, it should be promptly reported to the Bridge Program Administrator.


B.3 Role of the Inspection Program Administrator (Load Ratings)

In Minnesota, every MnDOT District, County, City (or other agency with inspection jurisdiction for abridge), must appoint a “Bridge Inspection Program Administrator” to oversee the bridge inspection andinventory. The responsibilities pertaining to load capacity ratings are outlined below. A Bridge InspectionProgram Administrator must be a registered Professional Engineer (PE), and must regularly attendMnDOT Bridge Inspection seminars.

B.3.1 MnDOT District Program Administrators

The MnDOT District Bridge Engineer (or District Bridge Inspection Engineer) will typically serve as theBridge Inspection Program Administrator. Responsibilities of a MnDOT District Bridge InspectionProgram Administrator include, but are not limited to, the following…

Review the inspection reports and structure inventory reports during each inspection cycle todetermine if changes in condition or dead loads indicate that a new load rating should beperformed. Note: the most recent load rating reports for trunk highway bridges are now availableon EDMS (Electronic Document Management System).

If a new load rating is required for a trunk highway vehicular bridge, the MnDOT District BridgeInspection Program Administrator should immediately contact the MnDOT Bridge Office LoadRating Engineer - [email protected] Note: additional field measurements may berequired to perform a load rating.

Verify that any load posting signage (if required) is in place, correct, and readable. If a load rating determines that a bridge must be posted (or that an existing posting be revised),

the posting signs must be installed within 30 days of the District being notified by the MnDOTBridge Office Load Rating Engineer. Note: significant changes in the posted limit may warrantinstallation of temporary posting signs until permanent posting signs can be installed. TheMnDOT District Bridge Inspection Program Administrator must notify the MnDOT BridgeOffice Bridge Management Unit when posting signs are in place.

The MnDOT District Program Administrator is responsible for contacting the railroad, ifinspections determine that damage or deterioration to a railroad bridge is sufficient to reduce theload carrying capacity of the structure (registered mail is preferred).

B.3.2 County/Local Program Administrators

The County or City Engineer will typically serve as the Bridge Inspection Program Administrator - citieswhich do not employ an engineer may elect to designate a private consultant engineer as the ProgramAdministrator. Responsibilities of a Bridge Inspection Program Administrator include, but are not limitedto, the following…

Verify that load capacity ratings have been performed on all vehicular bridges on the agencyroster.

Review the inspection reports and structure inventory reports during each inspection cycle todetermine if changes in condition or dead loads indicate that a new load rating should beperformed.

The online report “Load Posting & Rating Review” should be reviewed annually by the ProgramAdministrator. This report lists bridges that require load postings, bridges without a load ratingdate, and bridges that may require a new load capacity rating. Any errors or discrepancies shouldbe reported to the MnDOT Bridge Management Unit.

See that any required load ratings are promptly performed, and that the appropriate load ratingform is submitted to the MnDOT Bridge Management Unit to update the structure inventory.Many agencies will hire a consulting engineer to perform bridge load ratings, most culvert loadratings can be performed by the agency using Form 90.



Verify that load posting signage (if required) is in-place, correct, and readable. Note: township ormunicipalities should be promptly notified if load restriction signage is incorrect, missing ordamaged. A follow-up inspection should be performed to verify that the load posting signage hasbeen corrected, repaired or replaced.

If a new rating requires that a bridge must be posted (or that an existing posting be revised),posting signs should be installed as soon as reasonably possible, but no more than 30 days afterthe load rating date. Note: significant changes in the posted limit may warrant installation oftemporary posting signs until permanent posting signs can be installed.

County and City Programs Administrators should be aware of Minnesota Statute 165.03,Subdivisions 3 & 4, which require that “A report of the inspections shall be filed annually, on orbefore February 15 of each year, with the county auditor or town clerk, or the governing body ofthe municipality. The report shall contain recommendations for the correction of, or legal postingof load limits on any bridge or structure that is found to be under strength or unsafe”.

The Program Administrator is responsible for contacting the railroad, if inspections determinethat damage or deterioration to a railroad bridge is sufficient to reduce the load carrying capacityof the structure (registered mail is preferred).

B.4 Load Rating Review - Bridge Condition Ratings

The MnDOT Bridge Inspection report should be reviewed during each inspection cycle to see if there areany changes in condition which would suggest that a new load rating should be performed.

B.4.1 Changes in NBI Condition Ratings

As the NBI condition ratings for deck (FHWA Item #58), superstructure (FHWA Item #59), substructure(FHWA Item #60, and culvert (FHWA Item #62) describe the overall physical condition of the structure,they can be a useful tool for determining if a new load rating is required. The following general rulesshould be followed when reviewing the NBI ratings during each inspection cycle…

If an NBI condition rating falls to 4 (“poor” condition), the bridge inspection report and existingload rating should be reviewed to determine if a new load rating is required.

If an NBI condition rating falls to 3 (“serious” condition), a new load rating should be performed.

B.4.2 Changes in Structural Element Condition Ratings

As the structural elements describe the condition of specific bridge components, they can be useful indetermining if a new load rating is required, and for identifying which specific structural member requiresanalysis. While any structural element or smart flag rated at the worst condition state should be reviewedby the Bridge Inspection Program Administrator, the following general rules should be followed whenreviewing the structural element condition ratings during each inspection cycle…

If any portion of a primary structural element is rated in the worst condition state, the existingload rating and inspection notes (along with any photographs, sketches, or measurements) shouldbe reviewed to determine if a new rating is required. For painted steel elements, the worstcondition state is condition “5”, for unpainted weathering steel, concrete, timber, or masonryelements; the worst condition state is condition “4”. Note: see Section 3.4 for rating descriptionsfor structural elements (grouped by material type).

As section loss due to corrosion is a common problem on steel bridges in Minnesota, the SectionLoss smart flag (Element #363) should be reviewed. If the Section Loss smart flag is rated ascondition “4”, the existing load rating and inspection notes (along with any photographs,sketches, or measurements) should be reviewed to determine if a new rating is required. Note:rating descriptions for the section loss smart flag are outlined in Section 3.7.8.


B.5 Load Rating Review - Structure Inventory Items

Load rating information is displayed at the bottom right hand corner of the MnDOT Structure InventoryReport under the heading “Capacity Ratings”. This includes the design load, operating rating, inventoryrating, posting, rating date, and MnDOT permit codes. For more information, refer to the FHWA’s“Recording and Coding Guide for the Structure Inventory and Appraisal of the Nation’s Bridges”.

Note: updates to load rating inventory items can only be performed by the MnDOT Bridge ManagementUnit (this will be done after a load rating report is submitted).

B.5.1 Load Rating Date

For any bridge or culvert which carries vehicular traffic, the date of the most recent load rating dateshould be displayed on the MnDOT Structure Inventory Report.

If the load rating date is blank, it indicates that a load rating has not yet been performed, or that aload rating report form has not yet been submitted to the MnDOT Bridge Management Unit. Theonline report “Load Posting & Rating Review” will list any vehicular bridge without a load ratingdate (it will exclude railroad and pedestrian bridges).

An old load rating date does not necessarily mean that a new load rating is required. The loadrating date should be compared with the bridge inspection report to determine if the bridge hasdeteriorated significantly since the last load rating, or if additional dead load has been added sincethe last load rating.

The load rating date should be compared with the year of wearing surface installation year (nearthe bottom left corner), and the year that the bridge was remodeled or rehabilitated (near theupper left corner) - these may indicate that dead load has been added since the last load rating.

B.5.2 Wearing Surface Type, Depth and Year of Installation

In most cases, load rating calculations will be based upon the deck wearing surface type and depth itemsthat are displayed near the bottom left corner of the structure inventory report. As the deck wearingsurface can constitute a significant dead load, it will have a significant effect upon the load-carryingcapacity of the bridge.

A load rating analysis should typically be performed prior to installing a new wearing surface. If any changes to the wearing surface type or depth are reported during an inspection, the load

rating should be reviewed - any increase in the dead load will require a new load rating. In some cases, excess gravel may have to be removed from a bridge deck to maintain the current

posting limits. The MnDOT Bridge Management Unit should be contacted to update the deck wearing surface

type, depth, and year of installation items in the structure inventory.

B.5.3 Posting

The “Posting” item indicates what the load restriction signage at the bridge should read - if no posting isrequired, this item will be left blank. This item is displayed on the MnDOT Bridge Inspection Report (aswell as the MnDOT Structure Inventory Report). The NBIS and Minnesota State law require that bridgesbe posted if the maximum legal load exceeds the load permitted on the structure under the operatingrating stress level. The AASHTO manual states that a bridge should be capable of carrying a minimum of3 Tons (if not, the bridge should be closed to vehicular traffic). Examples of load posting signs are shownin Section 2.2.7 of the MnDOT Bridge Inspection Manual - for more detailed sign standards andguidelines, refer to the MnDOT Traffic Engineering Manual and the Minnesota Manual on UniformTraffic Control Devices. Note: if a bridge is posted with a weight restriction, this will affect the codingof FHWA Item #41 (Structure Open, Posted, or Closed) and FHWA Item #70 (Load Posting).


B.5.4 Operating Rating (FHWA Item #64)

The operating rating generally describes the maximum permissible live load level to which the structuremay be subjected - load postings (if required) are based upon the operating rating. Allowing unlimitednumbers of vehicles to use the bridge at operating level may shorten the life of the bridge. Special permitsfor vehicles which exceed the legal load may occasionally be issued by a governing agency - permitvehicles must not exceed the structural capacity determined by the operating rating. The MnDOTStructure Inventory report will display the operating rating as an “HS” loading. The operating rating itemdoes not apply to railroad or pedestrian bridges (it will be left blank). Note: The operating rating canaffect the coding of FHWA Item #70 (Load Posting).

B.5.5 Inventory Rating (FHWA Item #66)

The inventory rating generally corresponds to the live load level to which the structure can be safelysubjected to for an indefinite amount of time. The MnDOT Structure Inventory report will display theoperating rating as an “HS” loading. The inventory rating item does not apply to railroad or pedestrianbridges (it will be left blank). Note: The inventory rating can affect the coding of FHWA Item#67(Structural Evaluation), as well as the Bridge Sufficiency Rating.

B.5.6 Design Load (FHWA Item #31)

This item indicates the standard AASHTO truck live load for which the structure was designed - this willbe typically be designated as an “H” or “HS” followed by the gross tonnage of the design vehicle. An “H”designation is a is a single unit truck with two axles spaced at 14 ft. - 20% of the weight on the front axleand 80% on the rear axle. An “HS” designation is a two unit, three axle truck with 14 ft. between the frontand center axles (the spacing between the rear axles can vary). Newer bridges which have been designedusing Load Resistance Factor Design (LRFD) will be listed as “HL 93”. These are the possible designloads for FHWA Item #31…

H 10 H 15 HS 15 H 20 HS 20 HS 20 + Mod

HS 25 HL 93 (LRFD) Pedestrian Railroad Other or Unknown Not Applicable

AASHTO “HS 20” Truck Diagram

B.5.7 MnDOT Permit Codes (Trunk Highway Only)

The three MnDOT permit coding items (“A”, “B” and “C”) are used by the MnDOT Office of Freight andCommercial Vehicle Operations (OFCVO), to route overweight permit loads on state trunk highways -these three items are left blank for County, local, or other bridges not on the state trunk highway system.Under certain conditions, OFCVO may issue permits for vehicles exceeding the maximum legal weightlimit (these are outlined in Minnesota Statute 169). Annual permits allow unlimited trips for trucksweighing up to a maximum of 145,000 pounds. Single trip permits have no maximum weight, but arelimited by capacity of the bridges along the prescribed route. Note: vehicles traveling under anoverweight permit are prohibited by law from crossing a load posted bridge.

B.6 Load Rating Responsibility

B.6.1 Procedures and Qualifications

Federal Law, as outlined in the National Bridge Inspection Standards (NBIS), requires that bridges beload rated in accordance with procedures specified in the AASHTO Manual for Condition Evaluationof Bridges. The National Bridge Inspection Standards (NBIS) require that the individual charged withoverall responsibility for the load rating of bridges must be a registered professional engineer.

Bridge load rating calculations should be based upon all relevant information in the bridge file - thisincludes the original plans, reconstruction or repair plans, any structural modifications which haveincreased the dead load on the bridge, traffic data, and the existing structural condition (based upon themost recent inspection). MnDOT recommends that bridge load rating calculations be checked by anotherengineer. The skills necessary to perform a load rating varies considerably depending upon the type of thestructure - complex or non-redundant (fracture critical) bridges may require specialized engineeringknowledge.

B.6.2 Responsibility for Performing Load Ratings

Trunk Highway Bridges: Load ratings for Minnesota trunk highway bridges are performed by theMnDOT Bridge Office Load Rating Unit. Load ratings for truck highway culvert structures are the sharedresponsibility of the MnDOT Bridge Office and the District. For newly constructed trunk highwayculverts, the MnDOT Bridge Office Bridge Management Unit will fill out Form 90 and enter thecorresponding operating and inventory load ratings in the MnDOT database. The District is responsiblefor monitoring culvert conditions and consulting with the MnDOT Bridge Office Load Rating Unit ifchanges in condition indicate that a new rating may be needed.

County & Local Bridges: Load ratings for County/local bridges and culverts are the responsibility of theagency with inspection jurisdiction over the bridge. Counties and Cities will typically hire consultants toperform some (or all) of their load ratings.

Railroad Bridges: The Federal Railroad Administration (FRA) guidelines to railroads for the inspectionand management of railroad bridges are outlined in 49CFR 213, Appendix C. The railroad track owner isresponsible for ensuring that the bridge is capable of safely carrying all railroad traffic operated on thattrack, and for specifying the maximum loads that may be operated over the bridge. Load ratings forrailroad bridges are performed according to AREMA Manual for Railway Engineering. Load ratingsfor railroad bridges are not generally filed by MnDOT. Load rating information for a railroad bridge is notentered in the MnDOT database, and is not reported to the FHWA.


B.6.3 Load Rating Responsibilities of the MnDOT Bridge Office

MnDOT Bridge Office - Load Rating Unit: The MnDOT Bridge Office Load Rating Unit performsload capacity ratings for Minnesota trunk highway bridges (with some exceptions), develops the loadrating report forms, and provides data to the MnDOT Office of Freight and Commercial VehicleOperations (OFCVO), to route overweight permit loads on state trunk highways.

The MnDOT Bridge Office Load Rating Unit will perform load ratings on new trunk highway bridges,when a trunk highway bridge is remodeled, or when a MnDOT District requests a new load rating due tostructural damage of deterioration.

After being contacted by a MnDOT District that a bridge requires a new load rating, the MnDOTLoad Rating Engineer will perform a preliminary evaluation - the time frame for calculating a newload rating will depend upon the level of importance determined from the preliminary evaluation. Thefinal load rating (if necessary) should be completed within 45 days of the preliminary evaluation.

While the MnDOT Bridge Office Load Rating Unit does not perform load ratings for County/localbridges, they are available for technical assistance.

MnDOT Bridge Office - Bridge Management Unit

The MnDOT Bridge Office Bridge Management Unit files a copy of the load rating report for any bridge(Trunk Highway, County, City, Township, Etc) which carries vehicular traffic.

The MnDOT Bridge Office Bridge Management Unit is responsible for updating load rating items in thestructure inventory database and reporting load rating information to the FHWA. The NBIS requires thatload rating information for state trunk highway bridges be updated within 90 days of the load rating date,and that load rating information for County/local bridges be updated within 180 days of the load ratingdate.

For newly constructed trunk highway culverts, the MnDOT Bridge Office Bridge Management Unit willfill out Form 90 and enter the corresponding operating and inventory load ratings in the MnDOTdatabase.

B.7 Load Rating Methods & Forms

B.7.1 Load Ratings Methods (FHWA Items #63 & 65)

The method used to calculate a bridge load rating will be indicated on the load rating report, and isreported to the FHWA with Item #63 (Method used to determine operating rating) and Item #65 (Methodused to determine inventory rating). These two items are not currently displayed on the MnDOT StructureInventory Report. The following coding options are available…

Load Factor (LF) Allowable Stress (AS) Load and Resistance Factor (LRFR) Load Testing No Rating Analysis Performed

The majority of bridges on the MnDOT inventory are rated using the Load Factor (LF) method. The Loadand Resistance Factor Rating (LRFR) method is used on newer bridges designed according to LRFDBridge Design Specifications using the HL 93 design load. The Allowable Stress (AS) rating method istypically used only for timber or masonry bridges. The load testing method is seldom (if ever) used inMinnesota, and would be limited to special situations.


B.7.2 MnDOT Bridge Load Rating Forms

The results of a bridge load rating analysis should be summarized on a bridge rating and load postingreport form. MnDOT Load Rating forms can be found on the Bridge Office Web Site under the heading“Documents and Forms” (see link below).

http://www.dot.state.mn.us/bridge/docsdown.html

These are the MnDOT load rating and posting report forms…

Form RC-CL & RD-CL (Bridge Rating & Load Posting Report for County and Local Bridges) Form RC-TH & RD-TH (Bridge Rating & Load Posting Report for Trunk Highway Bridges) Form 90 (Culvert Rating Form) Form PIR (Physical Inspection Rating) Form PW (supplemental posting worksheet) TrussR (truss member rating form)

Any questions related to performing load ratings or filling out the MnDOT load rating and posting reportforms should be directed to the MnDOT Load rating Engineer. Immediately after a load rating isperformed, a copy of the appropriate MnDOT load rating and posting report form(s) should be submittedto the MnDOT Bridge Management Unit to update the structure inventory…

Bridge Management UnitMnDOT Bridge Office

3485 Hadley Avenue NorthOakdale, MN 55128-3307

Form RC-CL (County and Local Bridges): Form RC-CL is the bridge rating and load postingreport for County and local bridges - this form (along with all load rating calculations) must be retained inthe files of the bridge owner. A copy of Form RC-CL should be submitted to the MnDOT BridgeManagement Unit to update the structure inventory report (this will be retained in the files of the MnDOTBridge Management Unit).

Form RC-TH (Minnesota Trunk Highway Bridges): Form RC-TH is the bridge rating and loadposting report for Minnesota trunk highway bridges - this form (and any load rating calculations) isretained in the files of MnDOT Load Rating Engineer. A copy of Form RC-TH shall be forwarded to theMnDOT Bridge Management Unit to update the structure inventory report (this will be retained in thefiles of the MnDOT Bridge Management Unit). Note: Load rating reports for most trunk highway bridgesare now available through the MnDOT Electronic Document Management System (EDMS) to allowMnDOT Districts to view, download or print load rating reports.

Form 90 (Culvert Rating Form): Any culvert which carries vehicular traffic and is defined as“bridge” under Minnesota state law (total structure length of 10 ft. or greater), must have a load rating.New culverts, or culverts in fair or better condition with no evidence of distress due to normal trafficloads, can be rated using Form 90. Form 90 includes a table from which the inventory and operatingratings can be selected based upon the culvert design and material type. The inventory ratings shown inthe table are based upon the minimum original design load, regardless of original capacity.

Note: Before using the table on Form 90, the most recent bridge inspection report must bereviewed to confirm that the NBI culvert rating (FHWA Item #62) is condition 5 or greater. If theNBI culvert rating is 4 (“poor” condition) or lower, Form 90 cannot be used. Form PIR shouldthen be used to determine a reduced level for these ratings (it should be attached to Form RC-CLor RC-TH).

http://www.dot.state.mn.us/bridge/docsdown.html


Some other guidelines for using Form 90 include…

If the Form 90 table guidelines are not followed in determining the inventory and operatingratings, an explanation should be provided.

Box culverts with a clear span 20 ft. or greater cannot be rated using Form 90 - they must be ratedas a “bridge” (use Form RC-CL or RC-TH instead).

If a culvert is comprised of more than one culvert type or material, the segment with the lowestinventory and operating ratings will govern (this should be noted on Form 90).

Cast-in-place concrete box culverts are typically classified as either type “W” (generallyconstructed prior to 1944) or type “C” (generally constructed after 1945). As the type “W”culverts have less steel reinforcement, they will have lower inventory and operating ratings.

The Culvert Rating Form 90 should be retained in the files of the bridge owner - a copy of Form 90should be submitted to the MnDOT Bridge Management Unit to update the structure inventory report(this will be retained in the files of the MnDOT Bridge Management Unit).

Form PIR (Physical Inspection Rating Form): In situations where a load rating cannot readily becalculated, an evaluation by an engineer (based up the most recent inspection) may be used toapproximate the inventory and operating ratings. Form PIR (Physical Inspection Rating) may be used forone or more of following reasons…

No bridge plans are available. For concrete bridges where the steel reinforcement is unknown. If the superstructure has deterioration or damage which cannot be quantitatively measured, but

has obviously reduced the load carrying capacity of the bridge. If the substructure has deterioration, shifting, tipping or misalignment which obviously reduced

the load carrying capacity of the bridge, but the extent of the reduction cannot be readily becalculated.

A culvert with an NBI culvert rating of 4 (“poor” condition) or lower. A culvert posted with less than legal loads.

The rating is determined by the engineer upon careful consideration of all available information,including bridge condition (corrosion, spalling, damage, deflection, settlement, cracking, etc.), age, typeof construction, redundancy, ADT, loading (past, present, and future), etc. Engineering judgment or acombination of calculations, experience, and engineering judgment is used.

The numbers in the rating should follow this approximately ratio: (1.6 x HS Inventory Rating) = (HSOperating Rating) = (the posting weight in Tons for the single truck) = (0.625 x the posting weight inTons for a combination truck).

Note: Form PIR must be accompanied by the cover Form RC-CL or RC-TH. For type of analysis check“Other” and write in “PIR” and for method of rating check “No Rating Computations Performed.”

The Physical Inspection Rating Form PIR (attached to the cover Form RC-CL or RC-TH) must beretained in the files of the bridge owner. A copy of Form PIR (attached to the cover Form RC-CL or RC-TH) should be submitted to the MnDOT Bridge Management Unit to update the structure inventory report(these will be retained in the files of the MnDOT Bridge Management Unit).

Bridges rated using Form PIR should have all overweight permits prohibited, unless the bridge has adocumented history of carrying heavier trucks with no evidence of distress beneath the traffic lanes.


B.8 Load Rating References and Laws

References for performing bridge load capacity ratings include the following…

MnDOT LRFD Bridge Design Manual - Section 15 (2009)

AASHTO Manual for Bridge Evaluation (2008)

AASHTO Manual for Condition Evaluation and Load and Resistance Factor Rating (LRFR) ofHighway Bridges (2003)

AASHTO Manual for Condition Evaluation of Bridges (1994)

AASHTO Standard Specifications for Highway Bridges (2002)

AASHTO LRFD Bridge Design Specifications (2007)

AREMA Manual for Railway Engineering (2008)

Laws Pertaining to Bridge Load Ratings

The National Bridge Inspection Standards (NBIS) are outlined in the Code of Federal Regulations (CFR)Title 23: Highways, Part 650 - Bridges, Structures, and Hydraulics, Subpart C – National BridgeInspection Standards. Sections of the NBIS which pertain to bridge load capacity ratings include thefollowing…

CFR 650.303 - Applicability CFR 650.305 - Definitions CFR 650.309 - Qualifications of Personnel CFR 650.315 - Inventory CFR 650.317 - References

Minnesota State Rules and Statutes can be viewed on the following link…

https://www.revisor.leg.state.mn.us/pubs/

Some key Minnesota state laws pertaining to bridge load capacity ratings include the following…

Minnesota Rule 8810.9000, Subpart 7 - Rating (Definition) Minnesota Rule 8810.9500, Subpart 2 - Ratings Minnesota Statute 165.03, Subdivision 3 & 4 - Annual Reporting of Load Rating Changes Minnesota Statute 165.03, Subdivision 6 - Toll bridge load ratings reported every two years Minnesota Statute 169.80 - Size, Weight, Load Minnesota Statute 169.801 - Implements of Husbandry Minnesota Statute 169.822 - Weight Limitations & Definitions Minnesota Statute 169.824 - Gross Weight Schedule Minnesota Statute 169.826 - Seasonal Increases Minnesota Statute 169.8261 - Timber Products Minnesota Statute 169.84 - Load Limit on Bridge Minnesota Statute 169.86 - Special Permits Minnesota Statute 169.871 - Excess Weight Penalty Minnesota Statute 169.88 - Damages & Liability

https://www.revisor.leg.state.mn.us/pubs/


Appendix C: Safety Features (FHWA Item #36)

C.1 FHWA Item #36 (Traffic Safety Features)

FHWA Item #36 describes the adequacy of the bridge railing and approach guardrail from the aspect ofcurrent traffic safety standards (see pages 19-21 of the FHWA Recording and Coding Guide for theStructure Inventory and Appraisal of the Nation’s Bridges). During a bridge inspection, sufficientinformation should be recorded to determine the adequacy of these four safety features…

Item #36A - Bridge Railings Item #36B - Transitions (between approach guardrail and bridge railing) Item #36C - Approach Guardrail Item #36D - Approach Guardrail Ends

FHWA Items #36 A-D are displayed on the MnDOT Structure Inventory Report (halfway down theright hand side) - the coding for FHWA Item #36 should be reviewed during each bridge inspection.These four items are coded as follows…

Code Description Display

0Inspected feature does not meet currently acceptable standards

or a safety feature is required and none is provided.0-Substandard*

1 Inspected feature meets currently acceptable standards. 1-Meets StandardsN Not applicable or a safety feature is not required. N-N/A or Not Required- - Unknown (NBI)**

* The coding for FHWA Item #36 is based upon current standards for new construction orrehabilitation. Upgrading of an existing safety feature coded as “0-Substandrad” is generally requiredonly when Federal or State-Aid funding is used for a bridge (or roadway) improvement project.

** Any structure currently coded as “Unknown” for FHWA Item #36 A, B, C or D must be re-codedas either “0-Substandard” , “1-Meets Standards”, or “N-N/A or Not Required”.

FHWA Item #36 refers only to the roadway traveling over a bridge (or culvert) - these four items shouldbe coded as “N” (not applicable or not required) for railroad or pedestrian bridges.

The coding of FHWA Item #36 should not consider traffic damage or deterioration. Any damage ordeterioration on the bridge railings should be noted and rated using the appropriate railing element (seesection 3.3.10). Any damage or deterioration on the guardrail should be noted and rated using theguardrail element #982 (see section 3.8.2).

The coding of FHWA Item #36 can have a slight effect on the Bridge Sufficiency Rating, but only forbridges with a sufficiency rating or 50% or greater (see page B-9 of the FHWA Recording and CodingGuide for the Structure Inventory and Appraisal of the Nation’s Bridges). If two of these four items arerated as “0-Substandard” it will result in a 1% reduction, if three are rated as “0-Substandard” it willresult in a 2% reduction, and if all four are rated as “0-Substandard” it will result in a 3% reduction.

Disclaimer: The initial entry coding for FHWA Item #36 should not be assumed to be correct. Theexisting coding of FHWA Item #36 should not be the final determinant when deciding if safety featuresare required, or if existing safety features meet current design standards. A review and analysis of thesafety features present on a bridge should be conducted prior to any bridge improvement project.


C.2 FHWA Item #36A: Bridge Railing

FHWA Item #36A indicates if the bridge railings meet current traffic safety standards. Bridge railingsmust meet specific geometric criteria, must be strong enough to sustain vehicle impact, and must becapable of smoothly redirecting a vehicle after impact. With few exceptions, all vehicular bridges requirerailings - if no railings are present, FHWA Item #36 should typically be coded as “0” (substandard).Railroad or pedestrian bridges should be codes as “N” (not applicable).

Coding FHWA Item #36A for Culverts: If the embankment above a culvert structure is of sufficientdepth to allow guardrail to be installed along the roadway which is not directly connected to the culvert,FHWA Item #36A should be coded as “N” (not applicable). If guardrail is attached directly to a culvert -it should be considered to be a “bridge railing”, and FHWA Item #36A must be coded as either “0”(substandard) or “1” (meets standards).

FHWA Item #36A - Bridge RailingsCode Description Display

0Vehicular railings do not meet currently acceptable standards

or railings are required and are not present.0-Substandard

1 Vehicular railings meet current standards. 1-Meets StandardsN Not applicable or not required. N-N/A or Not Required- - Unknown (NBI)*

*Any structure currently coded as “Unknown” for FHWA Item #36A must be re-coded as either“0-Substandard” , “1-Meets Standards”, or “N-N/A or Not Required”.

The FHWA requires that bridge railings used on National Highway System (NHS) Federal-aid projectsmeet full-scale crash-test criteria in accordance with the guidelines contained in the NationalCooperative Highway Research Program (NCHRP) Report 350, “Recommended Procedures forthe Safety Performance Evaluation of Highway Features”. FHWA Railing policy, and examples orrailings which meet these criteria are listed on the link below…

http://safety.fhwa.dot.gov/roadway_dept/road_hardware/bridgerailings.htm

Current design standards for bridge railings are also available in the AASHTO LRFD BridgeSpecifications (Section 13), and the MnDOT LRFD Bridge Design Manual (Chapter 13). AASHTOdefines six crash test levels for which bridge railings (and guardrail) should be designed, based upontraffic and site conditions…

TL-1 (very low volume, low speed local streets) TL-2 (local and collector roads with favorable site conditions, reduced posted speeds, and small

numbers of heavy vehicles) TL-3 (high speed arterial highways with very low mixtures of heavy vehicles and favorable site

conditions) TL-4 (high speed highways, freeways, expressways and Interstate highways with a mixture of

trucks and heavy vehicles) TL-5 (similar to TL-4 where large trucks make up a significant portion of the average daily

traffic or unfavorable site conditions exist) TL-6 (high center of gravity vehicles - such as tanker trucks - are expected, combined with

unfavorable site conditions).

Table 13.2.1 (Standard Rail Applications) in the MnDOT LRFD Bridge Design Manual outlines theapproved applications for bridge railing designs currently used in Minnesota - it displays the AASHTOtest level and the speed limits for which these rail types are used.




C.2.1 MnDOT Railing Type Codes & Diagrams

The type of vehicular railings present on a bridge should be coded according to Table C.2.1 “MnDOTBridge Railing Codes” - this table should also be used for coding FHWA Item #36A. Table C.2.1includes diagrams of approximately 50 rail types (grouped by material and shape) commonly used inMinnesota, and indicates if these railing meet current design/safety standards. Note: the railing codediagrams shown in the 1995 MnDOT Recording and Coding Guide are outdated, and should not be usedfor coding FHWA Item #36.

MnDOT Rail Type Coding: The MnDOT rail type codes are displayed at the bottom left corner of theMnDOT Structure Inventory Report. They are listed as “Left Rail Type ID” and “Right Rail Type ID (the“left” and “right” hand directions are based by traveling in the direction of increasing referencestationing). This item should be updated if the bridge railings are reconstructed or replaced.

Criteria for Coding FWHWA Item #36A: To determine the appropriate coding for FHWA Items #36A,the type of vehicular railing present on the bridge should be confirmed, and design speed (or postedspeed, whichever is greater) of the roadway traveling over the bridge must be determined. For a bridgerailing to be considered as “meeting standards”, it must either meet the crash test standards outlined inNCHRP Report 350, or meet the 10-kip design load requirements from the AASHTO StandardSpecifications. Depending upon the roadway design speed (or posted speed, whichever is greater), therailing must also meet specific geometric criteria. The general railing criteria for low speed and highspeed roadways are as follows …

Design speeds ≥ 45 MPH

o Must meet either TL-4 crash test or 10 kip AASHTO design specificationso 2’-8” minimum heighto Curb projection (beyond face of rail) must not exceed 9”o No snagging hazards

Design speeds ≤ 40 MPH

o Must meet either TL-2 crash test or 10 kip AASHTO design specificationso 2’-4” minimum height

Table C.2.1 displays the current MnDOT rail type codes (along with diagrams of each type) - the tablewill indicate if the railing meets standards for all speeds, for speeds ≤ 40 MPH, or if the railing is considered to be substandard for all speeds. The commentary in the table will also indicate (with a nextto “yes” or “no”) if the railing meets each of the four criteria listed below...

NCHRP 350 Crash Tested AASHTO 10-kip Design Requirements Geometric Requirements (≥ 45 MPH) Geometrics (≤ 40 MPH)

Upgrading of Existing Bridge Railings: There is no requirement or obligation to upgrade existingbridge railings unless Federal or State-Aid bridge improvement funding is used on the bridge. Note: onlow speed roadways, bridge railings mounted on a sidewalk might not require upgrading (the sidewalkmust be at least 6 ft. wide, with a curb height between 8” and 10”).


MnDOT Railing Code List: The railings in Table C.2.1 are grouped by material type and shape, TableC.2.1A (below) provides an abbreviated description listed in numerical order. Railing codes #20 & 45have been eliminated, as there are no known any examples of these rail types in Minnesota.

Table C.2.1A - MnDOT Bridge Railing Type Code List (numerical order)Code Description Code DescriptionNN Vehicular Railings Not Required 31 Two-Line Concrete Railing

00 Substandard Railing (undefined) 32 Steel Angle Railing (Steel Posts)

01 Meets Standards for All Speeds (undefined) 33 Concrete Through-Girder Bridge

02 Meets Standards ≤ 40 MPH (undefined) 34 Steel Through-Girder Bridge

03 One-Line Concrete Railing w/6”Brush Curb 35 Steel Pipe Railing (Steel or Concrete Posts)

04 One-Line Concrete Railing w/Split Posts 36 Solid Concrete Railing

05 Two-Line Steel Tube Railing (Steel Posts) 37 Steel Plate Beam Guardrail w/ Timber Posts

06 Timber Post & Beam Railing 38 Timber Plank Railing

07 Concrete Railing (Type “G”) w/Pipe 39 One-Line Concrete Railing w/Narrow Beam

08 Concrete Railing (Type “G”) 40 Ornamental Metal Railing

09 One-Line Concrete Railing w/Pipe 41 Open Balustrade Concrete Railing

10 Concrete Railing (Type “D”) w/Pipe 42 One-Line Steel Bent Plate Railing (Steel Posts)

11 Concrete Railing w/Aluminum or Steel Pipe 43 Triple Beam Retrofit Guardrail

12 Concrete Railing w/Flat Tube 44 Reconstructed One-Line Railing (“J” Facing)

13 Concrete Railing w/Pipe 45 Concrete Rail (Type “J”) w/Hooked Anchors

14 One-Line Concrete Railing w/2-Line Pipe 46 Reconstructed One-Line Railing (2’-1” High)

15 Concrete Railing (Type “D”) w/2-Line Pipe 47 Reconstructed One-Line Railing w/Pipe

16 Concrete Railing w/2-Line Flat Tube 48 One-Line Concrete Railing w/6”Flush Curb

17 Concrete Railing w/2-Line Alum. or Steel Pipe 49 One-Line Concrete Railing w/10”Brush Curb

18 Concrete Railing w/2-Line Pipe 50 Glulam Timber Railing

19 Concrete Railing w/2-Line Alum. or Steel Pipe 51 Concrete “P-2” Parapet w/Steel Tube (TL-4)

20 This code is no longer used 52 Structural Tube “Wyoming” Railing (TL-4)

21 Concrete “P-1” Parapet w/Fence (Bikeway) 53 Three-Line Steel Tube Railing (TL-4)

22 Concrete Railing (Type “F” or “J”) 54 Two-Line Steel Tube Railing (TL-2)

23 Concrete Railing (Type “F” or “J”) w/Pipe 55 Timber Railing on Concrete Deck (TL-4)

24 Precast Railing (Type “J”) w/Straight Anchors 56 Timber Railing on Concrete Deck (TL-2)

25 Precast Railing (Type “J”) w/Hooked Anchors 57 Concrete Parapet w/Two-Line Tube (TL-4)

26 Laminated Timber Railing (Type “F” or “J”) 58

Reserved for future use

27 Concrete Parapet w/Two-Pipe Rail (Bikeway) 5928 Concrete P-1 Parapet w/Metal Rail (Bikeway) 6029 Reconstructed One-Line Railing (2’-4” High) 6130 Concrete Railing (Type “F” or “J”) w/Fence 62


Table C.2.1 - MnDOT Bridge Railing CodesCode Description Diagram (or Description)

NN Vehicular Railings Not RequiredUse this code for pedestrian bridges, railroad bridges,

or culvert structures that do not require railings.

00 Substandard For All SpeedsRailing cannot be accurately described by any of thetype codes in this table (this code should also be usedif vehicular railings are required but are not present).

01 Meets Standards For All SpeedsRailing cannot be accurately described by any of the

type codes in this table.

02Does Not Meet Standards ≥ 45 MPH

(Meets Standards ≤ 40 MPH) Railing cannot be accurately described by any of the

type codes in this table.

22

Concrete Railing Type “F”(Florida) or Type “J” (New Jersey)

Meets Standards For All Speeds

NCHRP 350 Crash TL-4 Yes No

AASHTO 10-kip Design Yes No

Geometrics (≥ 45 MPH) Yes No

Geometrics (≤ 40 MPH) Yes No

23

Concrete Railing Type “F”(Florida) or Type “J” (New Jersey)

with One-Line Steel Pipe

Does Not Meet Standards ≥ 45 MPH (Meets Standards ≤ 40 MPH)

NCHRP 350 Crash Tested Yes No


Geometrics (≥ 45 MPH)* Yes No


*The steel pipe railing is a snagging hazardand if removed, the 2’-4”concrete base is

too short for speeds ≥ 45 MPH.

24

Precast Concrete Railing Type “F”or “J” with Straight Anchor Bolts



AASHTO 10-kip Design* Yes No



*Substandard for speeds ≥ 45 MPH due to the questionable deck connection detail.



25

Precast Railing (Type “J”) withHooked Anchor Bolts

(MnDOT Standard Plate 5-397-140)







Precast Concrete Railing (Type J)Code #25

45

Concrete Railing Type “J” withHooked Anchor Bolts

(Retrofit on Existing Deck)







Retrofit Concrete Railing (Type J)Code #45

30

Concrete Railing Type “F” or “J”with Chain Link Fence (Bikeway)


NCHRP 350 Crash Tested* Yes No




*Substandard for speeds ≥ 45 MPH due to the fence mounted on top (snagging hazard).



08

Concrete Railing Type “G”(early 1970’s General Motors design)






*Railing must be at least 2’-8” high forspeeds ≥ 45 MPH.

07

Concrete Railing Type “G”(General Motors) with Steel Pipe






*Pipe railing is a snagging hazard and the2’-4”base is too short for speeds ≥ 45 MPH.

03

One-Line Concrete Railing with 6”High Brush Curb (9” Projection)




Geometrics (≥ 45 MPH)** Yes No


*Top rail beam must be at least 9” wide tomeet 10-kip design requirements.

**For speeds ≥ 45 MPH, the curb projection cannot exceed 9”.



04

One-Line Concrete Railing withSplit Posts

Does not Meet Standards ≥ 45 MPH (Meets Standards ≤ 40 MPH)






**1” post setback (1”) is a snagging hazard.

39

One-Line Concrete Railing(8” or 7” wide top beam)

Substandard For All Speeds



*As the top rail beam thickness is less than9”, these railings do not meet the 10-kip

design requirements.

48

One-Line Concrete Railing with 6”High Curb (Flush with Rail)







49

One-Line Concrete Railing(8” wide top beam with 10” High

Brush Curb)




*As the top rail beam thickness is less than9”, these railings do not meet the 10-kip

design requirements.



29

Reconstructed One-Line ConcreteRailing (2’-4” high excluding curb)

Meets Standards For All Speeds*





*For speeds ≥ 45 MPH, the total height (including curb) must be at least 2’-8” and

the curb projection cannot exceed 9”.

46

Reconstructed One-Line ConcreteRailing (2’-1” high excluding curb)






* For speeds ≥ 45 MPH, the total height (including curb) must be at least 2’-8” and

the curb projection cannot exceed 9”.

44

Reconstructed One-Line ConcreteRailing with Type “J” (New

Jersey) Facing






*Railing must be at least 2’-8” high forspeeds ≥ 45 MPH.



31

Two-Line Concrete Railing(1940’s-1950’s design)




36

Solid Concrete Railing

Does Not Meet Standards ≥ 45 MPH (Might Meet Standards ≤ 40 MPH)




Geometrics (≤ 40 MPH)** Yes No

*Unless an engineering analysis isperformed, older (pre 1964) concrete

railings should be coded as “substandard”.**Railing must be at least 2’-4” high for

design speeds ≤ 40 MPH.

41

Open Balustrade Concrete Railing

Substandard For All Speeds*




Geometrics (≤ 40 MPH)** Yes No

*Unless an engineering analysis isperformed, older (pre 1964) concrete

railings should be coded as “substandard”.**Railing must be at least 2’-4” high for

design speeds ≤ 40 MPH.

33

Concrete Through-Girder Bridge(early 1900’s design)






51

Concrete Parapet (Type P-2) withStructural Steel Tube Railing




57

Concrete Parapet with 2-lineStructural Steel Tube Railing


NCHRP 350 Crash TL-4* Yes No


*Although not crash tested, this designexception has been allowed due to the

similarity to Code #51

21

Concrete Parapet (Type P-1) with6 ft. Chain Link Fence (Bikeway)






*Fence is a snagging hazard, and the 2’-4”parapet is too short for speeds ≥ 45 MPH.

28

Concrete Parapet (Type P-1) withMetal Railing (Bikeway)






*Railing is a snagging hazard, and the 2’-4”parapet is too short for speeds ≥ 45 MPH.



27

Concrete Parapet Railing withTwo-Line Pipe Railing (Bikeway)






*Railings are a snagging hazard, the 2’-4”parapet is too short for speeds ≥ 45 MPH.

09

One-Line Concrete Railing withSteel Upper Pipe & Curb Pipe







**Upper pipe rail is a snagging hazard.

14

Concrete Railing with Two-LineSteel Pipe & Curb Cable







**Upper railings are a snagging hazard.

10

Concrete Railing (Type “D”)with One-Line Steel Pipe






15

Concrete Railing (Type “D”) withTwo-Line Steel Pipe



AASHTO 10-kip Design Yes No.

11

Concrete Railing with One-LineAluminum or Steel Pipe




*Upper pipe rail does not meet 10-kipdesign requirements.

47

Reconstructed Concrete Railingwith One-Line Pipe






*Rail height (including curb) must be atleast 2’-8” high, and curb projection must

not exceed 9” for speeds ≥ 45 MPH.

13

Concrete Railing with One-LineSteel Pipe




*Upper pipe rail does not meet 10-kipdesign requirements.



17

Concrete Railing with Two-LineAluminum or Steel Pipe




*Upper pipe railings do not meet 10-kipdesign requirements.

18

Concrete Railing with Two-LineSteel Pipe





19

Concrete Railing with Two-LineAluminum or Steel Pipe





12

Concrete Railing with One-LineFlat Tube




*Upper tube rail does not meet 10-kipdesign requirements.



16

Concrete Railing with Two-LineFlat Tube




*Upper tube railings do not meet 10-kipdesign requirements.

35

Steel Pipe Railing with Steel orConcrete Posts (1930’s design)




43

Triple Beam (“Thrie Beam”)Retrofit Guardrail


NCHRP 350 Crash Tested* Yes No




*Analysis must be performed to determine ifretrofit railings meet TL-4 and AASHTO 10-

kip design requirements.**Rail height (including curb) must be atleast 2’-8” high, and curb projection must

not exceed 9” for speeds ≥ 45 MPH.

52

Structural Tube Railing(Type “Wyoming”)




Upper rail beam is 6” x 4” x ¼” tubularsteel, lower rail beam is 6” x 3” x ¼”



53

Three-Line Tubular Steel Railing(State Aid Projects)




5” x 5” x ¼” tubular steel rail beams(top rail beam is 4” x 4” x ¼”)

54

Two-Line Tubular Steel Railing(State Aid Projects)





4” x 4” x ¼” tubular steel rail beams

05

Two-Line Steel Tube Railing withSteel Posts




42

One-Line Steel Bent Plate Railingwith Steel Posts






32

Steel Angle Iron Railing(Two-Line or Three-Line)




40

Ornamental Metal Railing




34

Steel Through-Girder Bridge




37

Steel Plate Beam Guardrail withTimber Posts & Curb






55

Timber Post & Beam Railing onConcrete Deck (TL-4)(State Aid Projects)




* The TL-4 design is nearly identical to theTL-2 design, but the TL-4 design requires six

curb bolts adjacent to each post.

56

Timber Post & Beam Railing onConcrete Deck (TL-2)(State Aid Projects)





*The TL-2 design is nearly identical to theTL-4 design, but will only have 4 curb bolts

adjacent to each rail post.



50

Glulam Timber Post & BeamRailing on Timber Deck (TL-2)





06

Timber Post & Beam Railing onTimber Deck (TL-2)





26

Laminated Timber Railing Type“J” (New Jersey)




38

Timber Plank Railing





C.3 Guardrail Requirements (Roadway over Bridge or Culvert)

Prior to coding FHWA Items 36-B (guardrail transition), 36-C (guardrail) & 36-D (guardrail ends), itmust first be determined if current construction standards would require installation of guardrail on thebridge approaches, or along the roadway traveling over the culvert. If it is determined that guardrail is notrequired, these three items should be coded as “N” (not applicable or not required). It is important to notethat installation or upgrading of guardrail on an existing bridge or culvert is typically only requiredduring a bridge or roadway improvement project.

C.3.1 Approach Guardrail Requirements for Bridges

The end of a bridge railing is a fixed object hazard that normally warrants the installation of approachguardrail, and there are typically other hazards present on a bridge approach (see figure below). Whileguardrail may also be warranted on the roadway traveling under a bridge, FHWA Items #36 B-D onlyaddress the roadway traveling over a bridge.

Potential Hazards at a Bridge Approach (Figure 10-7.01E – MnDOT Road Design Manual)

Guardrail Requirements - Bridges on the Minnesota State Trunk Highway System

For bridges on the Minnesota State trunk highway system (Interstate Highways, US Highways, andMinnesota State Highways), current guardrail requirements are outlined in Chapter 10-7.01.05 of theMnDOT Road Design Manual. Guardrail is required on bridge approaches unless all of the followingcriteria are met…

1. The bridge is located within the limits of a municipality2. The bridge site is located where design speeds are less than 40 mph3. The roadway is either an urban section with curbs and sidewalk or on a rural section in which the

bridge roadway width equals or exceeds the width of the approach roadway (including shoulders)

Guardrail Requirements - Bridges on the County/Local System

For bridges on County Highways, Township roads, City streets, or other roadways not on the MinnesotaState trunk highway system, current guardrail requirements are outlined in State of Minnesota Rule8820.9920 (Minimum Design Standards; Rural and Suburban Undivided Roadways; New orReconstruction Projects). Guardrail is required on bridge approaches if…

1. The design speed (or posted speed) exceeds 40 mph, and2. The existing ADT exceeds 400 or the bridge roadway width is less than the approach roadway

width (including shoulders)


C.3.2 Guardrail Requirements for Culverts

Culvert ends often warrant the installation of guardrail as the culvert headwalls and wingwalls are a fixedobject, the culvert end represents a sudden drop-off, and deep water is often present at culvert ends.

Culverts on the Minnesota Trunk Highway System

For culverts on the Minnesota State trunk highway system (Interstate Highways, US Highways, andMinnesota State Highways), current guardrail requirements are outlined in the MnDOT Road DesignManual. Chapter 10-7.01.04 of the MnDOT Road Design Manual states that hazards within the“roadside clear zone” (including culvert ends) typically warrant guardrail.

The roadside clear zone measured from the edge of the travel lane - this distance will vary dependingupon the embankment slope geometry, design speed, radius of horizontal curvature, the average dailytraffic (ADT), and the presence of curbs (a vaulting hazard). Chapter 4-6.04 of the MnDOT Road DesignManual provides a detailed description of roadside clear zones - it includes criteria, figures, graphs, andtables for determining the required clear zone distance, and includes examples of clear zone distancecalculations.

To provide a rough estimate of minimum roadside clear zone distances, a portion of Table 4.6.04A of theMnDOT Road Design Manual is shown below. Note: this table is only intended to quickly identifyexisting culverts without guardrail that should be coded as requiring guardrail for FHWA Item #36. Anyfinal calculations of clear zone distances should be based upon the criteria and tables in Chapter 4-6.04of the MnDOT Road Design Manual. Questions regarding the calculation of the roadside clear zonedistances should be directed to the MnDOT Design Standards Unit. [email protected]

Clear Zone Distances for Culvert Ends (Straight Roadway)Based upon Table 4.6.04A in the MnDOT Road Design Manual

Design Speed ADTEmbankment Slope (rise over run)

1:10 1:6 1:5 1:4**

40 mph*< 1,500 11 ft. 12 ft. 13 ft. 14 ft.

1,500-6,000 13 ft. 14 ft. 15 ft. 16 ft.> 6,000 14 ft. 15 ft. 16 ft. 17 ft.

45 mph< 1,500 14 ft. 15 ft. 17 ft. 20 ft.


50 mph< 1,500 16 ft. 18 ft. 19 ft. 23 ft.


55 mph< 1,500 23 ft. 25 ft. 29 ft. 33 ft.


60 mph< 1,500 26 ft. 29 ft. 31 ft. 38 ft.


70 mph< 1,500 29 ft. 32 ft. 35 ft. 43 ft.


*Guardrail is generally not required if the design speed is less than 40 mph.** Slopes steeper than 1:4 are not considered to be “recoverable”.

mailto:[email protected]?Subject=Standard%20Plans


Culverts on the County/Local System

For culverts not on the Minnesota State trunk highway system, Chapters 10-7.01 and 4-6.04 of theMnDOT Road Design Manual can also be used for determining when guardrail is required. Additionalguidance for low ADT roads (less than 1,500) is provided by State of Minnesota Rule 8820.9920 -“Minimum Design Standards; Rural and Suburban Undivided; New or Reconstruction Projects”. Note:this table is only intended to quickly identify existing culverts without guardrail that should be coded asrequiring guardrail for FHWA Item #36.

Clear Zone Distances for Culvert Ends (based upon Minnesota Rule 8820.9920)

ADTRecovery

Area*Design Speed

(mph)In-Slope

(rise over run)Roadway Surface

< 50 7 ft. 30-60 1:3 Aggregate50 - 149 9 ft. 40-60 1:4 Aggregate150 - 749 15 ft. 40-60 1:4 Paved

750 - 1,499 25 ft. 40-60 1:4 Paved> 1,500 30 ft. 40-60 1:4 Paved

*The “recovery” area is the obstacle-free area (measured from edge of traffic lane). For suburban roadways asdefined in part Mn Rule 8820.0100, the recovery area may be reduced to a 10 ft. (for ADT < 1,000) and reduced to20 feet (for ADT ≥ 1,000). If the posted speed limit is 40 mph or less, the recovery area may be reduced to 10 feet.

C.4 FHWA Item #36B: Guardrail Transitions

Whenever semi-rigid approach guardrail connects to a rigid bridge railing, a “crash-worthy” transition isneeded. Approach guardrail must be firmly attached to the bridge railing (or end post), gradually stiffenedas it nears the bridge, and configured such that impacting vehicles will not “snag” or “pocket”. FHWAItem #36B indicates if the transition from the approach guardrail to the bridge railing meets current safetystandards. Note: FHWA Item #36B only applies to the roadway traveling over the bridge - the rating doesnot take into consideration any collision damage or deterioration, the actual condition of the approachguardrail transitions should be rated using the guardrail element #982 (see Section 3.8.2).

FHWA Item #36B: Approach Guardrail TransitionsCode Description Display

0Guardrail transitions do not meet current standards (or

approach guardrail is required and is not present).0-Substandard

1 Guardrail transitions meet current standards. 1-Meets StandardsN Not applicable (or approach guardrail is not required). N-N/A or Not Required- - *Unknown (NBI)

*Any structure currently coded as “Unknown” for FHWA Item #36B must be re-coded as either “0-Substandard” , “1-Meets Standards”, or “N-N/A or Not Required”.

If guardrail is required (based upon current standards for new construction) but is not present,FHWA Item #36B should be coded as “0” (Substandard).

If approach guardrail is present on the roadway traveling over a bridge, FHWA Item #36B must(with very few exceptions) be coded as either “0” (Substandard) or “1” (Meets Standards).

If guardrail is present on the roadway over a culvert, and is not directly connected to the culvertstructure, FHWA Item #36B can be coded as “N” (Not Applicable).

Railroad or pedestrian bridges should be coded as “N” (Not Applicable).


General requirements for the installation and upgrading of bridge approach guardrail transitions areoutlined in Chapter 10.7.01.05 of the MnDOT Road Design Manual. Crash-worthy transitions arerequired at all new bridges, or on existing bridges if the railings are reconstructed, when the design speedis 40 mph or greater. When a bridge is located within the limits of roadway reconditioning orreconstruction project, existing transitions must be upgraded if the design speed is 40 mph or greater, andthe ADT is greater than 1,500. Approved bridge approach guardrail transitions are shown in the MnDOTStandard Plans Manual, series 600 (Safety Features & Special Structures).

C.4.1 Guardrail Transition Checklist

A guardrail transition includes several components, and includes an area extending 20-25 ft. from thebridge railing connection. If any component of the approach guardrail transition does not meet currentstandards, FHWA Item #36B should be coded as “0” (Substandard). The following checklist may be usedas a general guide for determining if a guardrail transition meets current design standards…

The bridge railing end post should be at least 3 ft. long, and at least 18” thick (at the base). A 4-bolt guardrail connection (MnDOT Standard Plate 8318C) should be present. The plate beam guardrail should be “double-nested” for the 12'-6" nearest the bridge. A curb transition or rub rail should be present below the guardrail at the bridge connection. The curb projection (if any) beyond the front face of the guardrail should not exceed 9". The guardrail post spacing should gradually reduce over the last 20-25 ft. nearest to the bridge. The two guardrail posts closest to the bridge should be a heaver design (8 ft. deep post).

C.4.2 Guardrail Transition Details

Bridge Railing End Posts: The bridge railing or end post must provide a sufficient anchorage for theguardrail. Current MnDOT standards require the end post to be at least 3 ft. long, 18” thick (at the base),and 2 ft. 8 inches high (at the downstream end). While slightly smaller end posts (with adequatereinforcement) might be sufficient, any transition with an end post smaller than the current standarddesign should be coded as “0” (Substandard). When upgrading the approach guardrail on an existingbridge, a new end post may need to be constructed (see MnDOT Standard Plan 5-297.609).

End Post Design for Concrete “F” Rail - MnDOT Bridge Detail Plan 5-397.114


Retrofit Bridge End Post - MnDOT Standard Plan 5-297.609

Railing Connection Details: The standard 4-bolt detail for the plate beam guardrail connection to abridge railing/end post is shown on MnDOT Standard Plate 8318C (see figure below) - this replaced anolder 2-bolt connection. Unless otherwise approved by an engineering analysis, any transition without thestandard 4-bolt guardrail connection should be coded as “0” (Substandard).

MnDOT Standard Plate 8318C: 4-Bolt Plate-Beam Guardrail Connection to Bridge

Curb Transitions and Rub Railings: To prevent an impacting vehicle from snagging on the bridge endpost, a guardrail transition should include either a curb transition or a rub rail (located just below theguardrail at the bridge connection). If neither is present, the transition should generally be coded as “0”(Substandard). On new bridges, the approach curb will gradually transition from 4” high to 10” high overthe 7 ft. adjacent to the bridge. Upgraded transitions on existing bridges without a curb transition willtypically employ a rub rail - this is a 6” steel channel running from the bridge end post over the length ofthe transition (typically around 25 ft.).


Curb transition on a bridge approach (from MnDOT Standard Plan 5-297.603)

Rub Rail Connection to Existing J-Rail (from MnDOT Standard Plan 5-297.606)

Approach Guardrail Transition Layouts: Approved bridge approach guardrail transitions are shown inthe MnDOT Standard Plans Manual, series 600 (Safety Features & Special Structures). The post spacing(and other details) on these plans will vary, but they generally include a reduced post spacing starting 20-25 ft. from the end of the bridge, and require two nested W-beam sections for the first 12 ft-6 in. adjacentto the bridge. Unless otherwise approved by an engineering analysis, any transition which does notconform to one of the MnDOT Standard Plans should be coded as “0” (Substandard). Some of theMnDOT Standard Plans for guardrail transitions are listed and/or diagramed below - they can be found atthis link… http://www.dot.state.mn.us/design/standard-plans/e-600.html

5-297.601 Guardrail Installations At Medians and End Treatments 5-297.603 New W-Beam Transition to Concrete F-Rail (Steel Post) 5-297.605 New W-Beam Transition to Concrete F-Rail (Wood Post) 5-297.606 Upgraded W-Beam Transition to Existing Concrete J-Rail (Wood Post) 5-297.607 New W-Beam Transition to Existing Concrete J-Rail (Wood Post) 5-297.609 New W-Beam Transition to One-Line Concrete Rail with New End Post (Wood Post) 5-297.614 W-Beam Transition to Thrie Beam Guardrail (for Bull Nose Medians) 5-297.617 Upgraded W-Beam Transition to Existing One-Line Concrete Rail 5-297.618 New W-Beam Transition to Existing Concrete J-Rail (Steel Post) 5-297.619 New W-Beam Transition to One-Line Concrete Rail with New End Post (Steel Post) 5-297.686 Steel Box Beam Guardrail Transition to Concrete F-Rail

http://www.dot.state.mn.us/design/standard-plans/e-600.html


Details from MnDOT Standard Plan 5-297.603 - W-Beam Transition to Concrete F-Rail (Steel Post)

Detail from MnDOT Standard Plan 5-297.606 -Upgraded Transition to Existing J-Rail (Wood Post)


Detail from MnDOT Standard Plan 5-297.609 - Transition to Existing One-Line Rail w/ New End Post

C.5 FHWA Item #36C: Approach Guardrail

FHWA Item #36C indicates if the approach guardrail on a bridge (or the guardrail on the roadway over aculvert) meets current safety standards. Approach guardrail should have adequate length and structuralqualities to shield motorists from the railing ends (and other hazards at the bridge site), and must becapable of safely redirecting an impacting vehicle. FHWA Item #36C generally applies to the section ofguardrail between the guardrail transition (Item 36-B) and the terminal (Item 36-D).

Note: FHWA Item #36C only applies to the roadway traveling over the bridge (not below the bridge), therating does not take into consideration any collision damage or deterioration - the actual condition of theapproach guardrail should be rated using guardrail element #982 (see Section 3.8.2).

Code FHWA Item #36C: Approach Guardrail Display

0Approach guardrail does not meet current standards or

guardrail is required and is not present.0-Substandard

1 Approach guardrail meets current standards. 1-Meets StandardsN Not applicable (or approach guardrail is not required). N-N/A or Not Required- - *Unknown (NBI)

*Any structure currently coded as “Unknown” for FHWA Item #36C must be re-coded as either “0-Substandard” , “1-Meets Standards”, or “N-N/A or Not Required”.

If guardrail is required (based upon current standards for new construction) but is not present,FHWA Item #36C should be coded as “0” (Substandard).


The standard types of guardrail used by MnDOT are outlined in Chapter 10-7.02 of the MnDOT RoadDesign Manual. If guardrail is required on a bridge approach, structural plate-beam “W-beam” guardrailis typically installed. While “Thrie” beam guardrail or box beam guardrail could also be used on bridgeapproaches, they have only been used to a limited extent in Minnesota. 3-cable guardrail (MnDOTStandard Plate 8330) is not generally used on bridge approaches, but may be used to protect culverts in


instances where deflection is not a constraint. Cable guardrail should not be installed along embankmentssteeper than 1:2, around the inside of a curve greater than 4 degrees or any place where the installationdoes not develop tension in the cable upon impact.

C.5.1 Bridge Approach Guardrail Layouts & Length Requirements

Figure 10-7.01C in the MnDOT Road Design Manual indicates where bridge approach guardrailshould be installed. On bridges with two-way traffic, guardrail should normally be installed for bothrailings on both ends of the bridge. On bridges with one-way traffic, guardrail should normally beinstalled for both railings at the approach end of the bridge. Depending upon the site conditions, guardrailmay also be required on the “downstream” end of the bridge. Basic layouts for bridge approach guardrailare shown in Figure 10-7.03F in the MnDOT Road Design Manual and on MnDOT Standard Plan 5-297.601 (Guardrail Installations at Medians & End Treatments).

Bridge Approach Guardrail Criteria (MnDOT Road Design Manual Fig. 10-7.01C)


The required length of guardrail installations is outlined in Chapter 10-7.03 of the MnDOT RoadDesign Manual. For bridge approach guardrail, the required length will depend upon design speed, ADT,horizontal curvature of the roadway, and the distance between the guardrail and the edge of the trafficlane (the “shy line offset). Hazardous site conditions such the steep approach slopes or fixed objects mayalso be a consideration. Table 10-7.03A in the MnDOT Road Design Manual outlines the designparameters for determining guardrail length. The length-of-need for guardrail at bridge ends normallyincludes the transition to the bridge rail as well as any portion of the end treatment that has re-directivecapabilities. Plate beam guardrail is typically installed in multiples of 12’-6” or 25 ft. (the standard platelengths). Determining the length of need for guardrail is a roadway design issue, but the inspector shouldnote any installation which does not appear to have sufficient length. Questions regarding the requiredlength of guardrail installations should be directed to the MnDOT Design Standards [email protected]

Typical Bridge Approach Guardrail Layout (MnDOT Road Design Manual Fig. 10-7.03F)

Design Parameters for Roadside Barrier Layout (MnDOT Road Design Manual Table 10-7.03A)



C.5.2 Structural Plate-Beam (“W-Beam”) Guardrail

Structural plate-beam (or “W-beam”) guardrail is the most commonly used traffic barrier in Minnesotaand the rest of the nation (see Chapter 10-7.02.01 of the MnDOT Road Design Manual). It derives itsname from the “W” shaped cross-section of the steel plate-beam.

Structural plate-beam guardrail is a “semi-rigid” system - impact is resisted by a combination of bendingand tension of the steel rail acting with the posts. Steel plate-beam may be used with timber posts(Standard Plate 8307) or steel posts (Standard Plate 8338). Design “A”, with post spacing of 12 ft-6 in., isused where the design speed is less than 50 mph - Design “B”, with a post spacing of 6 ft-3 in., is usedwhere design speeds are 50 mph or greater.

The centerline of plate-beam guardrail should typically be 1’-9” (21”) high - a variation of 3 inches fromthe nominal height is generally acceptable. Note: on plate beam guardrail transitions to existing concreteJ-rail, the guardrail centerline height gradually increases through the transition to 2’-2” high at therailing connection (see MnDOT standard plans 5-297.606 & 5-297.607) - these transition designs alsoinclude a rub rail below the plate beam guardrail.

The following checklist may be used to o determine if structural plate-beam guardrail meets standards…

Centerline of plate beam should be between 18” and 24” high (with the exceptions noted above) Maximum post spacing should be 6’-3” (50 mph or greater) or 12’-6” (less than 50 mph) The slope should not be steeper than 1:10 (extending at least 2 ft. behind the guardrail) The guardrail layout should correspond with the Standard Plans Manual, series 600 The overall length of the guardrail installation must be adequate for the site conditions (as defined

in Chapter 10-7.03 of the MnDOT Road Design Manual).

The centerline of plate-beam guardrail should typically be 21” high (a 3” variance is acceptable)

W 6 x 9 steel guardrail post W 8 x 21 steel guardrail post


C.6 FHWA Item #36D: Approach Guardrail Ends

As the exposed ends of plate-beam guardrail installations are themselves a hazard, the “upstream” endsmust have acceptable end treatments. FHWA Item #36D indicates if the approach guardrail terminationson a bridge (or the guardrail terminations on the roadway over a culvert) meet current safety standards.

Note: FHWA Item #36D only applies to the roadway traveling over the bridge (not below the bridge), therating does not take into consideration any collision damage or deterioration - the actual condition ofapproach guardrail terminations should be rated using guardrail element #982 (see Section 3.8.2).

Code FHWA Item #36D: Approach Guardrail Ends Display

0Guardrail terminations do not meet current standards or

guardrail is required and is not present.0-Substandard

1 Guardrail terminations meet current standards. 1-Meets StandardsN Not applicable (or approach guardrail is not required). N-N/A or Not Required- - Unknown (NBI)

*Any structure currently coded as “Unknown” for FHWA Item #36D must be re-coded as either “0-Substandard” , “1-Meets Standards”, or “N-N/A or Not Required”.

If approach guardrail is present on the roadway traveling over a bridge or culvert, FHWA Item#36D must be coded as either “0” (Substandard) or “1” (Meets Standards).

If guardrail is required on a bridge (or culvert), but is not present - FHWA Item #36D should becoded as “0” (Substandard).


C.6.1 Twisted End Treatments

The twisted-end treatment has been used on plate-beam guardrail for many years - however, these do notmeet current crash test criteria, as they present a “launching” hazard. Chapter 10-7.02.06 of the MnDOTRoad Design Manual outlines the policy for the upgrading of twisted end treatments…

1. Twisted-end treatments shall not be used on new plate-beam guardrail installations on any trunkhighway.

2. Reconditioning projects on which the in-place guardrail is disturbed require replacement oftwisted-end treatments with crash-worthy terminals on all roadways where the design speed limitis 40 mph or greater.

3. Reconditioning projects on which the in-place guardrail is not disturbed require replacement oftwisted-end treatments with crash-worthy approved terminals on all freeways and on expresswaysand other four-lane roadways where the design speed limit is 40 mph or greater. They also requirereplacement on two-lane roadways where the design speed limit is 40 mph or greater and thecurrent ADT is greater than 1,000. On roadways where the design speed limit is 40 mph orgreater and the ADT is less than the values specified above, the twisted-end treatments mayremain in place.

4. Twisted-end treatments can remain in place or be installed on any roadway off the trunkhighway system on which the design speed limit is less than 40 mph.

With the exception of criteria #4 above, if twisted-end treatments are present, then FHWA Item #36Dshould be coded as “0” (Substandard).


C.6.2 Guardrail Terminals and Crash Cushions (Selection Flow Charts)

Chapter 10-7.02.06 of the MnDOT Road Design Manual provides guidance for selecting theappropriate end terminal treatment, guidelines for updating existing guardrail ends, and lists approvedguardrail terminations - these include the following…

Eccentric Loader Breakaway Cable Terminal (ELT) Slotted Rail Terminal (SRT-350) Extruding Terminal (ET-2000 and ET-Plus) Sequential Kinking Terminal (SKT-350) Flared Energy Absorbing Terminal (FLEAT-350) Crash Cushion Attenuating Terminal (CAT) BRAKEMASTER Crash Cushion/End Terminal

FHWA Item #36D can be coded as “1” (Meets Standards), if any of the end treatments listed above arepresent. Other end treatments, crash cushions, or impact attenuators meeting the crash-test criteriaoutlined in the National Cooperative Highway Research Program (NCHRP) Report 350 could also becoded as “1” (Meets Standards). On divided highways with two adjacent bridges, the median guardrailwill typically have a “bull nose” terminal (see MnDOT standard plan 5-297.611).

A flow chart for selecting the appropriate termination for plate beam guardrail is shown in Figure 10-7.02H in the MnDOT Road Design Manual - photos and/or diagrams of end terminal designs are shownin Table C.6.3. At most locations, a flared terminal such as the ELT, SRT-350 or the FLEAT-350 shouldbe used. If there is not sufficient room for a 4 ft flare and 1:10 slope grading, a tangent terminal such asthe ET-2000/ET-Plus, SKT-350 or the variable flare FLEAT-350 should be used. However, as theseterminals allow vehicles to pass behind the terminal, and rapidly extrude guardrail off to the side, theyshould not be used on narrow medians or where pedestrians may be present. At locations where none ofthe other systems are appropriate, the CAT or the BRAKEMASTER can be used. Regardless of whichterminal design is used, it is important that the system be properly installed and that proper grading beprovided in order for the terminal to function as intended. The presence of curbs higher than 4” can be aproblem, as none of these terminals have been tested in this configuration.

End Treatment Selection Flow Chart (MnDOT Road Design Manual - Figure 10-7.02H)


Crash Cushions: Crash cushions (also known as crash attenuators) are explained in Chapter 10-8.0 ofthe MnDOT Road Design Manual. Crash cushions may be used in gore areas or medians whereguardrail cannot be adapted due to the site restrictions - they are often installed on bridge decks whereelevated roadways split or merge. The selection of a particular type of crash cushion will depend uponsuch factors as the obstacle width, the available space, and the relative probability of impact. Some crashcushions are designed to withstand multiple impacts without maintenance. A flow chart for the selectionof crash cushions is shown in Figure 10-8.06A of the MnDOT Road Design Manual - photos and/ordiagrams of crash cushion designs are shown in Table C.6.3.

General diagram showing a crash cushion

Crash Cushion Selection Flow Chart (MnDOT Road Design Manual - Figure 10-8.06A)


C.6.3 Guardrail Terminals and Crash Cushions (Identification Table)

Note: Table C.6.3 displays examples of guardrail terminals and crash cushions/attenuators for whichFHWA Item #36D could be coded as “1” (Meets Standards). This table is not intended to be a list ofapproved products, but is simply intended to aid in the identification of the guardrail terminations and/orcrash cushions present on a bridge. Most of the end treatments and crash cushions shown in this table arepatented, proprietary systems. Only the manufacturer (or an authorized representative) can provide themost recent and properly updated descriptions, designs, photos, or installation/maintenance manuals forthese systems. Additional information may be obtained electronically from the manufacturers' website –they will usually provide hard copies by customer request. These manufacturers offer a variety ofproducts not shown in this table which also meet NCHRP 350 standards. Any questions regardingspecific guardrail terminations or crash cushions should be directed to the MnDOT Design StandardsUnit. [email protected]

Table C.6.3 - Examples of Guardrail Terminals & Crash CushionsTerminal/Cushion Type Photo/Diagram

Thrie Beam Bull Nose Terminal

(Median of Divided Highways)

MnDOT Standard Sheet 5-297-611

The W-Beam guardrail will transition toThrie Beam guardrail before forming the

“Bull Nose” end treatment

ELT

Eccentric Loader Breakaway CableGuardrail Terminal (Flared)

Requires a flat (1:10) shoulder at least 9 ft.wide. Should not be on narrow medians or

adjacent to a sidewalk.

MnDOT Standard Plate 8329




SRT-350 TM

Slotted Rail Guardrail Terminal(Flared)

Requires a flat (1:10) shoulder at least 9 ft.wide. Should not be on narrow medians or


Trinity Highway Products, LLC.Dallas, Texas

highwayguardrail.com

FLEAT-350TM

Flared Energy Absorbing GuardrailTerminal

Flare can vary from 2 ft. 6 in. to 4 ft.Should not be on narrow medians or


Road Systems, Inc.Big Spring, Texasroadsystems.com

SKT-350TM

Sequential Kinking GuardrailTerminal

Should not be on narrow medians oradjacent to a sidewalk.

Road Systems, Inc.Big Spring, Texasroadsystems.com



ET-2000TM

Extruding Guardrail Terminal




ET-PlusTM

Extruding Guardrail Terminal




CATTM

Crash Attenuating Guardrail Terminalor Crash Cushion

May be as a guardrail terminal adjacent toa sidewalk. This crash cushion design isgenerally recommended for hazards 3 ft.or less in width with a low probability ofimpact, or on medians at least 20 ft. wide.Concrete anchorage or pad is not required.



BRAKEMASTER®

Guardrail Terminal or Crash Cushion

May be as a guardrail terminal adjacent toa sidewalk. This crash cushion design isgenerally recommended for hazards 3 ft.or less in width with a low probability ofimpact, or on medians at least 20 ft. wide.Concrete anchorage or pad is not required.

Energy Absorption Systems, Inc.Chicago, Illinois

energyabsorption.com



QuadGuard®

Crash Cushion/Crash Attenuator

This crash cushion design is generallyrecommended for hazards 3 ft. or less in

width with a moderate probability ofimpact, or on medians at least 20 ft. wide.

Requires a level concrete anchorage.



QuadGuard® (Wide)


This crash cushion design is generallyrecommended for hazards wider than 3 ft.

but less than 7 ft. Requires a levelconcrete anchorage.



TRACCTM



width with a moderate probability ofimpact, or on medians at least 20 ft. wide.

Requires a level concrete anchorage.



ENERGITE®


This crash cushion design is generallyrecommended for hazards wider than 7 ft.The layout of the sand-filled barrels (200lb. and 400 lb. size) must be approved by

an engineer.





REACT 350®



width with a high probability of impact (itcan withstand multiple impacts withoutresetting or repair). Incorporates plasticcylinders and a cable system - requires a

level concrete anchorage.



TAU II®


Incorporates barrel-shaped energyabsorbing cartridges. Requires a level

concrete anchorage.

Barrier Systems, Inc.Rio Vista, California

barriersystemsinc.com

SCI-100GM®


Incorporates a cable and hydrauliccylinders system. Requires a level

concrete anchorage.

SCI Products, Inc.Work Area Protection Corporation

St. Charles, Illinoisworkareaprotection.com

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