MBTA Bundles Bridge Replacements to Upgrade Transit Infrastructure
The Massachusetts Bay Transit Authority (MBTA) has replaced six bridges along its commuter rail lines as part of its Capital Investment Plan. The 5-year, $8 billion plan is focused on upgrading the aging infrastructure along the Framingham/Worcester, Lowell, Haverhill, and Newburyport/Rockport rail lines.
The rail bridge replacement project targeted those structures nearing the end of their useful lives. Those crossings include Bacon Street, Intervale Road, and High Line supplied by Coreslab Structures. Parker Street, Lynn Fells Parkway, and Commercial Street supplied by Fort Miller. The new structures have a service life of 75 years and will reduce future maintenance costs and service impacts along the commuter rail system.
The design-build bridge bundle method reduced costs and streamlined design and construction.
Vanasse Hangen Brustlin, Inc. (VHB) partnered with Barletta Heavy Division to provide track design and construction as well as ancillary roadway and utility work. The team worked closely with the MBTA on a public engagement campaign to keep commuters informed of project impacts and progress.
While each bridge had its own set of challenges the six bridges used precast concrete for the substructure along with consistent details that simplified design, fabrication and installation. Precast was a critical part of the Accelerated Bridge Construction (ABC) methods used to minimize rail disruption and the impact to the traveling public.
The design-build bundling effort reduced design and construction time and provided a single provider for both design and construction which promoted collaboration between engineers, contractor, and MBTA staff.
Precast concrete and ABC used were to overcome the low headroom accompanying these old structures. Precast concrete pile caps, back walls, wing walls and approach slabs facilitated the scheduled replacement over a weekend. The construction sequence started with the demolition of the old bridge and then moved to the assembly of the proposed bridge superstructure with minimal impacts to the traveling public. In order to avoid substantial temporary easements for off-site work zones the bridges were moved into place during weekend track outages via self-propelled modular transporters (SPMTs).
Construction of the new bridge that carries the Framingham/Worcester Line over Intervale Road in Weston began in March, 2021 and was completed in the summer of 2022. The original steel bridge was built in 1914 and was at the end of its useful life. The replacement structure has a 75 year service life and a three-track bridge design that could accommodate future construction.
The replacement of the bridge that carries the Needham Line over Robert Street was completed in the Fall of 2021. The steel bridge, which was built in 1898 and last rehabilitated in 1985, was completely replaced to meet the MBTA’s reliability and modernization needs.
The single span bridge design with higher clearance provided more open space below. The single-track bridge design can accommodate future construction of a second track.
The use of ABC and precast concrete substructure minimized the impact to the transit riders and the local communities. The upgrades to the rail crossings provides safer and more reliable service on the commuter rail lines.