ACCELERATED BRIDGE

CONSTRUCTION

THE CLAYTON STREET BRIDGE

REPLACEMENT

Malek Al-Khatib, P.E.,Vice President , Project Manager | Louis Berger

ASCE & SEAM January 15, 2015

Background

History of the Clayton Street Bridge

• First Massachusetts Bay Transportation Authority (MBTA) transit bridge built using Accelerated Bridge Construction (ABC) methods

• Built in 1911 and modified in 1926

• Deteriorated three-span steel structure with steel bents

• Replaced in 2013 with a single-span steel structure, thus opening up the street and the sidewalks below

• Design completed September 2012

• New structure erected November 2013

• Located in the Dorchester

neighborhood of Boston,

Massachusetts

• Mix of residential industrial

neighborhoods

• Part of the MBTA Ashmont

Red Line

• Frequent truck route

Location MapDorchester, Massachusetts

Clayton St. Bridge

Quick Facts

Field

Corner

Station

Braintree

Branch

• Steel elements showed

signs of deterioration

• Original 13’-10”

clearance was not

sufficient for current

truck traffic

• Steel bents blocking the

roadway caused hazards

for motorists and

obstructed sidewalks for

pedestrians

Old StructureCondition

steel bents

Through Girder Deck

Structure

obstructed sidewalks

13’-10” clearance

Challenges

Structure

• Low Clearance

• Truck collision damage

proved that low clearance

was an ongoing issue that

had to be fixed

Community and MBTA Red Line Operation

• Residential abutters cross the street from the bridge

• MBTA Red Line trains could not be shut down on

weekdays

• Limited number of possible Red Line weekend

shutdowns

• Coordination with other MBTA construction projects

Notice for public information meeting

Challenges

Challenges

Structure

500 ft. radius track curve

Challenges

Structure

50 degree bridge skew angle

Challenges

Structure

• Converting 3 span

structure to a single span

• Existing abutments

couldn’t sustain the load

increase

Challenges

Structure

• Framing Configuration

Challenges

MBTA System

• Traction power lines run

through the bridge

• Third rail and heater cables

run through the bridge and

were in poor condition

• Signal and communication

system was outdated and

not well plotted

• Rail sprinkler system runs

through the bridge and was

in poor condition

Challenges

MBTA System

• Conduct testing and tagging of signal and communication cable.

• Replace antiquated signal system and reducing the number of conductor cables from 500 to around 80

• Replace several manholes and junction boxes.

• Cannot combine power and signal cable conduits

• Maintain MBTA System operational.

Rendering for temporary bridge

Construction Site Constraints

• Limited ROW

• Heavy traffic on Clayton Street during rush hours

• City ordinance regarding noise and work hours

• Limited number of possible streets shutdowns

• Coordination with the utility companies

Challenges

• Clayton Street Bridge

clearance is the highest in

the area.

• Narrow residential one way

streets

• Main streets are congested

weekdays.

ChallengesTraffic Management Plan

(Clayton Closed & Dickens Closed

Weekend Hourly Schedule

Temporary BridgeUsed to re-route MBTA

systems off bridge during

construction

• Temporary bridge built in

Spring 2013 to re-route

cables off existing

structure

• Minimized interference

with train service during

construction

• (Left) temporary bridge

completed with utility

ducts re-routing utilities

System Work

System work without

interrupting service

• Systems were

replaced, re-routed

and/or upgraded

• New manholes were

installed

• New cables and

junction boxes

improved service

Strengthening Existing Abutments

40ft deep minipiles

85ft long tieback soil

anchors

Installation of tiebacks and mini piles

Strengthening Existing Abutments

40ft deep minipiles

85ft long tieback soil

anchors

Installation of tiebacks and mini piles

Strengthening Existing Abutments

Proposed Bridge

Existing BridgeInstallation of tiebacks and mini piles

Strengthening Existing

Abutments

Installation of Tiebacks

• 85-foot-long tiebacks

installed at design

angle while avoiding

existing steel bents

• Installed during two

weekend street

shutdowns while trains

were operational over

the bridge

Installation of Mini Piles

• 40-foot-long mini piles

cored through top of

existing abutment

• Installed during three

weekend Red Line

shutdowns while

keeping the streets

open below

Strengthening

Existing Abutments

New Bridge

Constructed on site

• New superstructure was

pre-assembled in the shop

• New superstructure

arrived in five panels and

was fully assembled onsite

• New superstructure was

assembled in yard

adjacent to existing

structure

• New structure was erected

on scaffolding

SPMT Units – ABC Construction

Self Propelled Modular Transit Units

• Two SPMT Units were used to transport bridge

• SPMT Units moved simultaneously and were controlled

by one operator

• Tires of SPMT Unit had 360º rotation capabilities for

ease of mobility and precision when placing new

structure on bearings

• Steel plates were placed along the path of the SPMT to

ensure proper load bearing capacity

Veteran’s Day

Weekend

• Friday Nov. 8, 2013:

Demolition; preparation

began after last train

• Saturday Nov. 9, 2013 at

noon: Clayton Street was

cleared of debris

Veteran’s Day Weekend

Preparing the Substructure

• Saturday 10 p.m.: Bearings and backwalls were

installed

• Existing backwalls were sawn off and cleaned along

with the existing bridge seats

• New backwalls were installed

• Lesson learned: Place down new bridge prior to

installing backwalls

• New bearings were installed and locations were

confirmed by surveyor

• Lesson learned: Ensure bearings and bearing

plates are level prior to placing down bridge

Veteran’s Day Weekend

Moving the Superstructure

• Saturday 5:30 p.m.: Bridge started to move

• SPMT Units lifted the bridge off the scaffolding at 5:30 p.m. on November 9th

• Media and residents gathered to watch the 500,000lb structure slowly roll into place

• Saturday 10:30 p.m.: Substructure modifications were completed, and the bridge began moving to its final position, and lowered on the new bearings.

• Bridge was successfully placed on the bearings and the track and ballast were replaced

• Sunday Nov. 10, 2013: bridge was completed.

• Monday 12:05: Track work completed for Monday morning service

• Service resumed for Monday morning commuters on schedule

ABC Planning/Design/Construction

Basic Elements

• Detailed planning, design, and constructability reviews.

• Proposed means and methods included in the bid documents.

• Attention to all details that affect schedule.

• Risk assessment and minimize unforeseen conditions.

• Detailed construction scheduling during the design phase, including hourly schedules and assignment of responsibilities, were necessary for success of weekend installation

• Detailed scheduling and dry-runs with the contractor to ensure smooth delivery

• Collaboration and open communication between owner, contractor and designer ensured a smooth weekend

ABC Planning/Design/Construction

Benefits of Accelerated Bridge Construction

• By conventional techniques, the replacement would

have taken an additional 10 months and $2 million to

complete

• Conventional methods would have resulted in several

weeks of Red Line and street closure

• Community engagement drove the project schedule

and ultimate success

• Due to proper preparation, work that was initially

scheduled for a 3-day weekend was successfully

completed in a 2-day weekend with no injuries or

accidents

Replacement Sequence 3D Animation

• The bridge was painted a light grey color to match surroundings

• Formliner was added to the face of the abutment walls

• New sidewalks were constructed and the roadway was paved and cleared

• New street lighting under the bridge

Finishing Touches

formliner

sidewalks

14’-0” clearance

lightings

Before & After

• Clearance was increased from 13’-10” to 14’-0”

• Sidewalks were widened

• Steel bents were removed

• Bird netting was installed to protect bridge seats

• Formliner was added for esthetics

Planning, attention to details, and partnering = Success