Through our national reputation as a leader in Accelerated Bridge Construction, CME was selected by MassDOT to investigate if it was possible to replace a complicated bridge structure in the middle of a congested downtown area, flanked by large buildings, that carries commuter railways, highways, major City throughways, and one of the heaviest traveled sidewalks in the State. CME was able to deliver a viable solution that included developing a phased-construction plan and incorporation of innovative design solutions including Accelerated Bridge Construction (ABC) techniques to minimize the overall impacts to the public.
Sophisticated shoring and staging methods were implemented during the substructure project (Phase 1) to allow construction activities to take place while high-volume traffic and commuter rail operations continued through the work zone. In Phase 2, ABC techniques were employed to expedite the replacement of the superstructure and incorporate improvements for pedestrians and bicyclists.
This complex project involved the rehabilitation and replacement of substructure elements (Phase 1) and full-replacement of superstructures (Phase 2) carrying Commonwealth Avenue and MBTA Green Line over I-90 (Massachusetts Turnpike) and MBTA Commuter Line in downtown Boston. The structures are located immediately east of the Allston Viaduct near Boston University and Fenway Park necessitating continuous coordination with stakeholders, utilities and railroad lines to minimize disruption to everyday operations.
CME and team members developed construction documents for a substructure rehabilitation project through the MassDOT Design-Bid-Build procurement process for Phase 1, Substructure Replacement. CME performed a detailed substructure retaining wall inspection, substructure design, preliminary bridge design and load rating. CME also worked to satisfy the needs of the project related to public outreach with the stakeholders, utility coordination, including both railroad lines, and construction assistance related to our specific roles on the project. The rehabilitation of the abutments and replacement of the piers were constructed and completed in 2015 in preparation for the Phase 2 of the project.
For Phase 2, the Superstructure Replacement, CME performed a preliminary design of the three-span bridge comprised of three different structures. Two of the structures carry Commonwealth Avenue (Comm. Ave.) EB and Comm. Ave. WB, while the third structure carries the MBTA Green Line over the MBTA Commuter Line and Interstate 90/Massachusetts Turnpike (Mass. Tpke.) EB / WB. The Green line superstructure and Comm Ave EB was replaced during the summer months when traffic was minimal and the following summer the Comm Ave WB structure was replaced after a year of utility relocation to the EB structure. The traffic on the Mass Turnpike was managed with a movable barrier and a crossover that limited the number of lanes in each direction at various times of the day.
Over the course of the entire project, CME performed preliminary investigations and inspections; developed preliminary design plans for the proposed superstructure; prepared contract documents for the substructure improvements; and created RFQ/RFP documents for the superstructure replacement for a Design-Build (DB) procurement.
The project also included numerous logistical complexities which CME coordinated including extensive coordination for utility relocation (gas, electric, water, communications, etc.); collaboration with municipalities, private stakeholders and public safety operations; ongoing public outreach efforts to commuters and residents; and organization with several private and public transportation projects simultaneously occurring in this corridor.
During construction, CME assisted the District Construction Office with management and oversight of the superstructure project construction. The bulk of the construction work was performed in short duration closures during the summer using a multitude of ABC techniques where longitudinal precast panels with concrete closure pours and SPMTs were used to deliver girder pairs from a nearby assembly area.