Nobis has been selected by the Massachusetts Bay Transit Authority (MBTA) to provide advanced preliminary engineering and final geotechnical design services for the Green Line Extension (GLX) project as part of the AECOM | HNTB GLX Joint Venture. The GLX Project will extend the MBTA Green Line from a relocated Lechmere Station in East Cambridge to Union Square in Somerville and College Avenue in Medford. The total construction cost is estimated at $1.3 billion.
The proposed GLX service extension consists of two branches, the mainline branch which will operate within the existing right-of-way of the MBTA Lowell Line, beginning at a relocated Lechmere Station in Cambridge and traveling north to Medford, and a tributary branch line operating within the existing right-of-way for the MBTA Fitchburg Line to Union Square in Somerville. Seven new stations will be constructed as part of the project. A vehicle maintenance facility (VMF), Transportation Building, and Elevated Parking Deck will also be constructed. Five highway bridges over the rail lines and three railroad bridges over existing roadways will be replaced to accommodate the rail corridor improvements. Once completed, trains will operate every five to six minutes in the peak periods, providing fast and efficient service to downtown Boston.
Nobis recently completed geotechnical services for Task 1A, the advanced preliminary engineering phase of the project and is currently providing Task 1BC final design services. These services include coordination of the final design subsurface exploration and laboratory testing program, geotechnical engineering for shallow foundations, ground improvement recommendations for stabilization of soft soils and existing urban fill with aggregate piers, and deep foundation design for both large and small diameter drilled shafts, micropiles, and driven piles. Nobis will also provide geotechnical engineering for the design and analysis of cantilever and anchored retaining walls systems planned along the right-of-way.