Introduction to Bridge Design and
Construction 1
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Introduction to Replacement Bridge Planning and Design
Questa Engineering Corporation
Sydney Temple, P.E.
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Introduction
Today’s Talk:
Basic site analysis and investigation Geotech, Hydrology, Roadway, etc.
Bridge designs types Abutment/Foundation types
Bridge Deck types
Design exercise
Permits and review processes
Construction issues
Retrofits
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Why Bridges?
Bridges have better Flood Control performance
Less back water, better conveyance, safer
Geomorphic flexibility Maintains sediment transport, vertical
movement
Fisheries benefits Removes migration barriers, facilitates
movement, provides habitat
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Introduction to Bridge Design and
Construction 2
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Multi-Discipline Approach
Structural Engineering
Geotechnical Engineering
Civil Engineering
Planning and Permitting
Hydrology Science
Hydraulic Engineering
Biologic Evaluations
Geologic Evaluations
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Basic Design Approach
Investigate the site
Survey and geotech
Layout bridge location
Bridge Deck and foundation design
Hydraulic Design
Approach design
Permitting
Construction
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Site Survey Data
A GOOD SURVEY IS NEVER A WASTE OF MONEY!!
Survey site General topographic for 100 feet upstream downstream min.
Channel slopes Long profile at 350 feet upstream and downstream
Make sure controlling tailwater zones are surveyed
Existing structure data Slope, shape, dimensions, top of roadway, top of culvert, apron
slopes and wing wall geometries
Make sure bridge approach roads are surveyed including edge of pavement, roadway crowns, super elevations
Map utilities and nearby structures
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Site Analysis
Site analysis:
Layout
Geotechnical Considerations
Hydrologic/Hydraulic Studies
Geomorphic Considerations
Biologic issues
Introduction to Bridge Design and
Construction 3
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Bridge Layout – Structure Positioning
Right of Way
Jurisdictional determination
Alternative alignments
Approaches
Vehicular
ADA Requirements
Traffic/Roadway design
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Roadway Design Issues
Alignments
Approach elevations
Vertical Curves
Will you need embankments or other retaining structures
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Geotechnical Studies
Investigative procedures
Drilling rigs and types
Constraints
Report preparation
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Types of Geologic Investigations
Regional gelogic and seismic conditions
Soil conditions
Geologic hazards
Subsurface exploration
Analysis
Design recommendations
Introduction to Bridge Design and
Construction 4
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Local Geologic Map Detail of Cambria Area
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Soils Map
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Regional Seismicity and Geology Review
Alquist-Priolo Earthquake Fault Zone Maps
Seismic Hazard Zone Maps
Liquefaction
Seismic Induced Slope Instability
Seismic Shaking Hazard Maps
Regional Geologic Mapping
Regional Slope Stability Mapping
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Drilling, Logging and Sampling of Boreholes
Exploratory holes 10 feet into bedrock or required depth in soils
Soil sampling at depth intervals to collect samples for analytical testing
Perform Standard Penetration Test (SPT) sampling for strength characteristics (I.e. Blow Counts/ft)
Determine groundwater levels
Introduction to Bridge Design and
Construction 5
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Drill Rigs
Type of rig depends upon many factors;
Depth of hole,
required rock penetration,
potential for hole collapse,
sampling requirements, and
access restrictions
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Drill Rigs
Portable Augur Drill Rig
Truck/track mounted Augur Drill Rig
Mud or Air Rotary Drilling
Cone Penetration Testing
Re: Specialized drilling services may take time to schedule
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Types of Drilling
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Reviewing Boring Logs
Logs of test borings show summaries of data
Soil density
Soil material
Blow counts
Fewer blow counts - looser less dense material
High blow counts - solid denser soil conditions
Groundwater levels
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Introduction to Bridge Design and
Construction 6
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Foundation Type Feasibility Review and Laboratory Testing Request
Review Logs of Boreholes and Determine Feasible Foundations based on subsurface conditions
Determine Samples and Testing Protocol for Soils Laboratory
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Geotechnical Engineering Analysis
Foundation bearing capacity
Site seismic design criteria
Pier Friction Capacity
Liquefaction Analysis
Site Geology and Soil Conditions
Geologic Hazards
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Session Break
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H & H Investigations
Hydrology data
Hydraulics analysis
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Hydrologic Analysis
Hydrology Information
Gage data
Hydrologic models
Comparable basin analysis
Governmental sources; Caltrans, FEMA, and County Flood Control Agencies
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Construction 7
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Hydraulic Analysis
Hydraulic analysis
FishXing
HEC-RAS
Alternative Hydraulic models
Must have the ability calculate back water impacts
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Project Site
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Hydraulic Modeling
HEC-RAS
Good design tool accepted by most if not all agencies for analysis
Requirements:
Accurate topographical survey
Surveyed benchmarks
Hydraulic structures
Bridge soffit/roadway measurements
Slope
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Design Water Surface elevations
Hydraulic Design Criteria and Freeboard
Vary by Jurisdiction
50-year with 2 ft of freeboard
100-year with at least 1 ft freeboard
Levees – three of freeboard
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Construction 8
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Bridge Design and Impacts
Goal: shortest bridge with the least amount of impact
Design Criteria
Passes design flows with freeborad
50-year with 2 ft of freeboard
100-year with at least 1 ft freeboard
No increase in flood threat
Minimizes scour and deposition
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Bridge Scour Analysis
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Bridge Scour
Event Based scour vs. Long-term scour
Hydraulic Engineering Circular (HEC) 18,
"Evaluating Scour at Bridges," FHWA-IP-
90-017
Geomorphic evaluations
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Geomorphic Analysis
Vertical & Lateral Creek Movement
Sediment Transport
Bankfull channel
Low-Flow (scour line) Channel
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Introduction to Bridge Design and
Construction 9
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Determining Vertical and Lateral Creek Movement
Historic profile analysis
Existing condition long profile analysis
Historic air photo examination
Historic topographic map analysis
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Lateral movement
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Longitudinal Profile Analysis
70
80
90
100
110
120
130
140
150
-1+50 3+50 8+50 13+50 18+50 23+50 28+50 33+50
River Station (ft)
Flo
w L
ine
Ele
va
tio
n (
ft)
Reach 3Reach 2Reach 1
Mitigated Knickpoint (armored)
Un-mitigated Knickpoint
Dri
sco
ll R
oad
Pal
m A
ven
ue
SF Aqueduct,
concrete
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Longitudinal Profile Analysis
Determines average slope through the site
Assesses offsite bed slope issues
Places project site in context with upstream downstream areas
May indicate bed aggradation
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Fall 2003 March 2005
Introduction to Bridge Design and
Construction 10
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Design Breakdown
Foundation design
Bridge deck design
Channel Design
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Bridge Foundation Considerations
Required Load Capacity and Anticipated Uses
Site Conditions & Geotechnical Investigations
Foundation Types Spread Footings
Driven Piles
Drilled Cast-In-Place Piers
Economic Analysis Capacity and Service Life versus Cost
Typical Construction Costs
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Required Load Capacity and Anticipated Uses
Public Trails -
Pedestrian/Bicycle/Equestrian/Disabled Users
Light-Duty – Typically Residential
Automobiles/Light Trucks
Highway Traffic – Heavy Trucks HS20-25 loads
(AASHTO Load Standards)
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AASHTO & Caltrans
American Association of State Highway and Transportation Officials
National Association which establishes and promotes highway construction and safety standards.
California Department of Transportation
Manages State Highway System
Issues permits for encroachment into state owned highways and properties
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Typical Light-Duty Bridge Crossing Profile
80
0+00 0+40 0+80 1+20 1+60 2+00 2+40 2+80
94.4
94.3
94.1
93.5
93.1
90.7
89.7
86.0
82.9
81.2
83.9
86.5
92.5
96.0
97.0
98.0
98.8
99.7
100
.2
100
.2
100
.2
100
.2
100
.2
99.2
98.2
97.2
90
100
94.4
95.3
96.2
97.1
96.8
96.7
2+91
80
90
100
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Introduction to Bridge Design and
Construction 11
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Foundation Types - Spread Footings
Relatively shallow reinforced concrete mats to distribute bridge loads over wide area of supporting soils.
Advantages
Typically least expensive option
Minimal equipment mobilization requirements
Disadvantages
– Not suitable over soft or liquefiable soils
– Minimal resistance to undermining or slope instability
– Moderate to heavy site disruptions
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Typical Spread Footing Bridge Foundation
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Foundation Types - Driven Piles
Tubular and Sheet Steel, Reinforced Concrete or Composite Piles driven into soils using a dropped weight or piston hammer, applied typically in marine settings.
Advantages Minimal site disruption
Provides support over soft or variable subgrade conditions
Applied in areas prone to flooding or with very soft soils
Disadvantages Requires mobilization of large equipment and materials
Requires minimum embedment depth into soil
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Reinforced Concrete Piles Being Installed in a Marine Environment
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Foundation Types - Drilled Cast-In-Place Piers
Drilled holes filled with cast-in-place reinforced concrete piers.
Advantages Typically provides greatest resistance to vertical and lateral
loads
Provides excellent resistance to scour
Used in steep and/or unstable slope areas
Disadvantages Typically highest cost
Difficult to apply in areas of shallow ground water or loose soils
Moderate site disruptions
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Drilled Pier Foundation Design for Timber Framed Bridge
#4 BAR
#4 BARS
FOR STEM WALL
1'
3'-4"
14'-8"
#4 HOOPS @12" O.C.
4 #5
3" COVER3' COVER
58" X 12" ANCHOR
BOLT @ 48" O.C.
12"
#4 HOOPS @12" O.C.
4 #5
9 #5
7 #4
8"
12"
1'
5'-8"
10'-0"
12"
8"
3" COVER
3" COVER
2'-4"
7 #4
12"
12"
12"
12"
14'-8"
3'-8"
10'-0"
#5 #4
C'
B
3" COVER3" COVER
#4 HOOPS @12" O.C.
4 #5
#4 HOOPS @12" O.C.
4 #5
3' MIN.
12"
12"
7 #4
B
PLANSECTION B-B'
SECTION C-C'
SECTION A-A'
C
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Construction 12
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Photo of Drilled Cast-In-Place Pier Installation
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Economic Analysis
Capacity and Service Life versus Cost
Typical Cost for Light-Duty Bridges $1,000/ft for pre-fabricated steel bridges
w/ wood decking
$2,000/ft installed including design and foundations
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Concrete Box Girder
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Introduction to Bridge Design and
Construction 13
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Bridge Widths
12 foot width lanes plus 2 feet of railing/curb
Single lane = 18 feet, 14 feet between railings/curbs
Two Lane = 28 feet, 24 feet between railings/curbs
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Planning Level Bridge Costs
Pedestrian Bridge construction costs in northern California $125-$140 per square feet (sf) for cast in place concrete, $115-$150 per sf for prefabricated bridges. $1,500 per lineal foot
Traffic Rated Bridges Two Lane light to medium traffic
$350-500 sf
Major arterial structures $600-$750 sf
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Picture of ferrasci improvements
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Introduction to Bridge Design and
Construction 14
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Project Concept
CEQA
Certification
Flood Control
Public Safety
Permits
Environmental
Permits
Implementation
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Permits and Approvals
Documents needed for permitting
Permitting procedures
Design Review
Construction implementation
Construction management and inspection
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Project Permit Documents
Site Map Water of the USCOE Jurisdictional Area Project Description Detailed Alternatives examined/project justification 30% design drawings
Project Analysis Technical analysis or separate back up design
memorandum (H&H, Geotech, etc.)
Biologic Reconnaissance
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Project Description
Project Justification Site plan
Project channel bed profiles
Project cross section views
Habitat enhancement features
Limits of work
Area of impact
USCOE, riparian area, vegetated area
Determination of cut and fill quantities
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Environmental Permits
U.S. Army Corps of Engineers 404 Permit
Endangered Species Act Consultation
California Department of Fish & Game Streambed Alteration Agreement
Regional Water Quality Control Board
Water Quality Certification & General Stormwater Construction Permit
Coastal Development Permit
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USCOE Permits
Reviews application and notifies National Marine Fisheries Service (NMFS) and/or US Fish and Wildlife Service (USFWS)
May ask for formal or informal consultation
May require preparation of a Biologic Opinion (BO) and/authorization for take
NMFS will review Fish passage analysis
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Construction 15
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Streambed Alteration Agreements
CDFG engineering staff will review project fish passage analysis
Must have CEQA completed to issue
Includes impacts to riparian areas
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Biological Reconnaissance
Special-Status Species
Existing Habitat ID and Mapping
Proposed Habitat Mitigation
OHWM/Wetland Delineation
CNDDB Search
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Coastal Development Permit
Usually processed through the County
May require architectural review
May require separate monitoring protocols
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Public Safety Permits
County/ City Building Permits
Structural & Roadway Design Review
Caltrans
Encroachment permits
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Construction 16
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Caltrans Encroachment Permit
Primarily concerned with impacts to their facilities and safety
Reviews design storm hydrology and hydraulics
Erosion and bank stabilization in and around their facilities
Maintenance responsibility
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County/City Review
Reviews detail plans and calculations
Roadway design
Structural design
Geotechnical design
Flood control
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CEQA Review
Categorical Exemption
Initial Study Preparation
Mitigated Negative Declaration
EIR/EIS
Lead Agency
City or County
CDFG for some grant funded projects
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Permit Timeline
6 month is likely minimum
1 year is not out of the question
NMFS and USFWS have 135 days
CDFG - 30 days
Coastal Development Permit
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Construction Factors
Site and Channel Access
Work Conditions
Restricted Seasons
Mobilization and Staging Areas
Materials Storage Areas
Dewatering
Limits of Work
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Construction 17
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Construction Issues Access & Staging
How are you going to get to the site?
Dewatering issues
Do access roads need to built?
How will machinery move around the site?
Where will work be staged?
Material and spoils storage
Maintenance and fueling areas
Delivery truck access and traffic issues?
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Construction Sequence
Water control
Foundation construction Drilling
Concrete forming
Channel demo and grading
False work/deck forming
Pre-stressing/curing
Installation
Approaches
Erosion control
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Construction Inspections
Inspections are very important - use construction inspection forms
Extensively photograph work progressing
Inspection Milestones:
Staking and job layout
After clearing and grubbing, new topo may be taken to estimate quantities
After rough grading
During rock placement/willow staking
During LWD/in-stream structures placement
Check step pool elevation and depths as you go!!
After erosion control installation; during and after planting and irrigation installation