A CCELERATED B RIDGE C ONSTRUCTION THE C LAYTON S TREET B RIDGE R EPLACEMENT ASCE & SEAM January 15, 2015 Malek Al-Khatib, P.E., Vice President , Project Manager | Louis Berger
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
Location Map Dorchester, Massachusetts Quick Facts • Located in the Dorchester neighborhood of Boston, Field Corner Massachusetts Station • Mix of residential industrial Clayton St. Bridge neighborhoods • Part of the MBTA Ashmont Red Line • Frequent truck route Braintree Branch
Old Structure Condition Through Girder Deck Structure • Steel elements showed signs of deterioration • Original 13’ - 10” clearance was not 13’ - 10” clearance sufficient for current steel bents truck traffic • Steel bents blocking the roadway caused hazards for motorists and obstructed sidewalks obstructed sidewalks for pedestrians
Challenges Structure • Low Clearance • Truck collision damage proved that low clearance was an ongoing issue that had to be fixed
Challenges 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 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• Third rail and heater cables run through the bridge and were in poor condition • Signal and communication system was outdated and not well plotted • Rail sprinkler system runs through the bridge and was in poor condition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 Rendering for temporary bridge cables from 500 to around 80 • Replace several manholes and junction boxes. • Cannot combine power and signal cable conduits • Maintain MBTA System operational.
Challenges 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 Traffic Management Plan (Clayton Closed & Dickens Closed • Clayton Street Bridge clearance is the highest in the area. • Narrow residential one way streets • Main streets are congested weekdays.
Weekend Hourly Schedule
Temporary Bridge Used 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 Installation of tiebacks and mini piles 85ft long tieback soil anchors 40ft deep minipiles
Strengthening Existing Abutments Installation of tiebacks and mini piles 85ft long tieback soil anchors 40ft deep minipiles
Strengthening Existing Abutments Installation of tiebacks Existing Bridge and mini piles Proposed Bridge
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
Strengthening Existing Abutments 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
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 9 th • 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
Finishing Touches • The bridge was painted a light grey color to match surroundings • Formliner was added to the face of the abutment walls • 14’ - 0” clearance New sidewalks were constructed and the roadway was paved and cleared • formliner New street lighting lightings sidewalks under the bridge
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
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