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Ontario’s Rapid Installation of Single Span Bridges

Kent Street Overpass and other bridges

on Highway 417 in Ottawa

May 2016

PRESENTATION OVERVIEW

History and existing conditions

Renewal options

Unique design and construction challenges

Lessons learned

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BACKGROUND

Location

History

Existing conditions

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LOCATION

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EXISTING STRUCTURE

WBL Structure EBL Structure

Typical Section

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GENERAL HISTORY

Original EBL and WBL structures built in 1965

Single variable span – variable depth rectangular voided slab

reinforced concrete structures

Rehabilitation in 1985 (new barriers and exp. joints, deck

patch, concrete overlay, w/p pave and substructure repairs)

Curved abutments (R= 67 m and 85m) on steel ‘H’ piles

WB: 4 traffic lanes EB: 3 traffic lanes

AADT of 160,000 (2015)

Table 1: Summary of Existing Girder Range of Variable Span and Depth

Structure Existing Girder No. Span (m) Depth (mm)

HWY 417 EB G1 31.34 1969

G7 23.28 1635

HWY 417 WB G8 23.23 1635

G16 18.87 1245

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STRUCTURE EXISTING CONDITION

Debonding of concrete overlay

Overlay had reached the end of

its useful service life (28 years

old)

Parent concrete questionable

Probable active corrosion in 0%

and 3% of WBL and EBL deck

Chloride content generally below

0.025% threshold

Deck soffit in fair condition

Substructure in fair condition

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RENEWAL OPTION – SCOPE OF WORK

Conventional superstructure rehabilitation

(40 yrs) vs rapid replacement (75 yrs)

Conventional rehabilitation ruled out (90+

years old, unknown conditions, formwork

removal)

Rehabilitation of existing abutments and

wingwalls with concrete refacing,

sacrificial galvanic anode system

Semi-integral conversion and removal of

ballast walls

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SUPERSTRUCTURE ALTERNATIVES

Slab on steel plate girder (800 mm – 1300 mm depth)

Slab on 1250 mm - 1400 deep steel box girder

Slab on 900 mm – 1500 mm deep CPCI girder

Slab on B 800 – B1000 prestressed box girder (side-by-

side or spaced)

Post-tensioned concrete structure

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PREFERRED ALTERNATIVE

Slab-on-steel girder

Shallower structure allows

increasing existing vertical

clearance from 4.54 to 4.79 m

Design and fabricate custom

girders to suit variable spans

Light superstructure –

reduced seismic demand

Uniform behavior achieved

by varying depth/stiffness to

produce more or less equal

deflections at adjacent

girders

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UNIQUE DESIGN AND CONSTRUCTION

CHALLENGES

Unknown ballast wall and bearing seat condition

Ballast wall removal

Semi-integral abutment conversion

Bearing design

Temporary lateral restraint

Structure plan geometry - variable span/depth, skew, curved end

Staging area

SPMT support points

Watermain – rapid demolition

Rapid replacement constraints

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BEARING SEAT ACCESS

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BALLAST WALL REMOVAL

Removal on weekends with rolling

lane closures

Track-mounted circular saw

Stabilization with temporary lateral

restraint

Granular backfill directly against

structure

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SEMI-INTEGRAL ABUTMENT CONVERSION

Pre-rapid lift condition

Final condition

Sawcut and remove ballast

wall in advance of rapid lift

Stabilize structure for skew

effects

Place perforated subdrain and

temporary backfill

Excavate and remove existing

structure

Place Evafoam blocking

Install new structure

Post rapid lift – form and

pump concrete

Place bearing seat overlay

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BEARING DESIGN

Offset new and existing bearings

Adjustable bearing design

Lateral restraint (skewed forces and seismic)

Legend: = existing bearing seat = new bearing seat

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BEARING DESIGN

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TEMPORARY LATERAL RESTRAINT DEVICES

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DECK PLAN GEOMETRY

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STRUCTURE PLAN GEOMETRY

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VARIABLE SPAN/DEPTH STRUCTURE

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BEARING REACTIONS

WBL

EBL

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SHEAR DIAGRAMS

During Transport on SPMT’s

Permanent Position

WBL structure

EBL structure

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BENDING MOMENT DIAGRAMS

During Transport on SPMT’s

Large negative moments due to skew. Additional

reinforcing steel required to prevent cracking of the

deck during rapid lift

Permanent Position

WBL structure

EBL structure

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STAGING AREA

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SPMT SUPPORT POINTS

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RAPID STRUCTURE DEMOLITION

1200 dia. water main presented construction challenges

Contractor movement plan was based on SPMT

configuration with heavier axle loadings

Contractor presented change proposal (later) to carry out

rapid demolition

Avoid travelling over water main with existing structure

New structures are much lighter than existing (420/440

tonnes vs 820/900 tonnes)

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RAPID STRUCTURE DEMOLITION

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RAPID STRUCTURE REPLACEMENT

EBL Structure - 440 tonnes

2 sets of self-propelled

modular transporters

(SPMT’s)

8 axles, 64 wheels

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RAPID STRUCTURE REPLACEMENT

WBL Structure - 420 tonnes

2 sets of self-propelled modular

transporters (SPMT’s)

8 axles, 64 wheels

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RAPID REPLACEMENT

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LESSONS LEARNED

Survey plan is a must (knowledge of existing structure geometry –

ballast wall/bearing seat elevations/dimensions)

Design flexibility – bearings, geometry, existing bearing conditions

Movement plan should be prepared several weeks in advance

(before fabrication) and to be reviewed by designer and owner

Travelling over utilities – let the Contractor design own temporary

methods but designer to ensure feasible methods exist

Make provisions for repair/adjustment of elements that cannot be

inspected before the removal of the existing structure (ballast

walls, abutment seats, etc.)

Coordinate lift procedure with fabrication of steel girders.

(Additional bearing stiffeners were added because the Contractor

adjusted the lift points)

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LESSONS LEARNED

Use road plates under

SPMT travel path,

especially after heavy

rain, it’s 5:00 am, you are

stuck and cannot get a

hold of the SPMT tow

truck

road plate

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ACKNOWLEDGEMENTS

AECON – General Contractor

SARENS – Subcontractor For Rapid Lift Move (Constructability

Review)

MAMMOET – Rapid Lift Specialist (Constructability Review)

McIntosh Perry – Contract Administrator

MMM Design Team – Adriano DiRienzo – P. Eng., Andrew

Krisciunas – P. Eng., Michael Matthews – P. Eng., Gary Greenan

MTO – Dina Miron P. Eng., George Collins, P. Eng. – Structural

Regional Office

MTO – David Glass P. Eng., Chad Manion – Construction (and

Photographs)

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Questions?

https://www.youtube.com/watch?v=FREdt1jPxHA

http://www.cbc.ca/news/canada/ottawa/kent-street-

bridge-replacement-captured-on-video-1.3290421

E-mail contact info:

Dina Miron – dina.miron@ontario.ca

Michel Vachon – vachonm@mmm.ca

Kent Street Overpass - time lapse video/media coverage

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