The MBTA announced major work taking place this spring 2020 on the Green Line as part of the Green Line Extension project (GLX) and the Green Line Transformation Program (GLT): the closure, relocation, and complete replacement of Lechmere Station to take place for approximately one year; rehabilitation work on the Lechmere Viaduct; and scope and design work to take place the East Cambridge Viaduct.
•Lechmere Station Construction
Lechmere Station will be closed for approximately one year beginning in the spring of 2020 to remove and relocate the existing station as part of GLX. During Lechmere’s closure beginning in the spring, Green Line service between Lechmere and North Station will be replaced with shuttle bus service. Shuttle service will be provided by either MBTA buses or a third party with a Request for Proposals process currently underway. Commuter bus routes (Routes 69, 80, 87, and 88) will continue to provide service to the existing busway at Lechmere Station during the Green Line service suspension. GLX continues to closely coordinate with MassDOT on bus priority feasibility and with the Cities of Cambridge and Boston on termini arrangements.
During Lechmere Station’s closure, the GLX team is closely collaborating with the GLT team to also close and replace the existing Lechmere Viaduct.
•Lechmere Viaduct Construction
In December 2019, the MBTA’s Fiscal and Management Control Board awarded a $62 million contract to SPS New England, Inc., to rehabilitate the Lechmere Viaduct, a project managed by GLT in coordination with GLX. This project also necessitates the closing of Lechmere Station, which is already planned to be closed and reconstructed as part of GLX.
The current Lechmere Viaduct’s existing railing, deck, and stringer conditions warrant replacement due to extensive chloride intrusion and map racking of the concrete. Additional concrete and steel repairs are also necessary to extend the life of the structure. The structure’s current load rating indicates the concrete arches are below statutory requirements for revenue vehicles and work cars, and require restrictions on speed and number of simultaneous trains.
Improvements to come on the Lechmere Viaduct include new track and ties, deck, and stringer systems; renewed and reinforced infrastructure with arch spans and floor beams strengthened with CFRP Polymer wrap systems; a new concrete bridge railing system; new track, signal cables, and duct bank systems, overhead catenary poles, and power transmission system; and additional concrete repairs.
When complete, benefits to the Lechmere Viaduct include a reduction in future maintenance and repair costs in the long term; increased load-carrying capacity of the main structure to enable increased revenue service; a reduction in ongoing maintenance and repair costs as well as accelerated construction; a uniform appearance; an upgraded system that meets current operating standards; and the extension of the service life of the bridge while conserving the historic concrete structure built in 1910.
A Notice to Proceed was issued on January 14, 2020, with an approximate construction duration of eighteen months. Pre-construction activities to take place from January through April 2020 include surveying the existing conditions, shop drawings and submittal reviews, the installation of all work platforms, the installation of temporary fiber optic lines, the cleaning of concrete structures, and coordinating with various state and local agencies, historic commissions, and others.
During the construction period from May to September 2020 in which a track outage between North Station and Lechmere Station is required, construction includes arch strengthening with CFRP wrap; the repair and strengthening of floor beams; the removal and replacement of deck and stringer systems; the removal and replacement of track and ties; repairs to bascule span steel; and catenary, power, and signals systems replacement.
Testing will take place from October 2020 to March 2021. Construction will continue from October 2020 through July 2021 without a track outage needed and regular Green Line service resuming beyond North Station. Activities during that time include concrete repairs, railing replacement, and additional interior and pier repairs.
•Lechmere Viaduct Additional Design & Construction Phase Services
This week, the MBTA’s Fiscal and Management Control Board authorized to amend a current contract to Vanasse Hangen Brustlin, Inc. (VHB) for a sum not to exceed $3 million for construction phase services (CPS) and additional design services for the repair/rehabilitation of the Lechmere Viaduct Project. The contract completion date was also extended to April 26, 2022.
With VHB as the designer of record and due to an aggressive construction schedule, the MBTA project team recommended VHB for consultant continuity as VHB possess both the historical knowledge and technical abilities necessary for the project. The previous total project budget was $73,878,073 with a contract completion date of April 27, 2020. VHB has been awarded $3 million for CPS and additional design services with the contract completion date also extended to April 26, 2022.