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MBTA Green Line Extension Project

Arora Engineers (Arora) was part of the AECOM/HNTB joint venture team responsible for design development for the Green Line Extension Project’s advanced conceptual design. The project was an initiative of the Massachusetts Department of Transportation (MassDOT) and the Massachusetts Bay Transportation Authority (MBTA) to provide a direct rail link connecting the underserved areas of Downtown Boston to Union Square in Somerville and College Avenue in Medford.

The project extended the existing Green Line service from a relocated Lechmere Station in East Cambridge to Somerville and Medford. Designs for the project included six stations, 4.3 miles of Green Line light rail tracks, the relocation of four miles of double track commuter rail, extensive bridge repair and development, and a vehicle maintenance storage facility.


Arora was tasked with systems design and documentation for the stations and the transportation office building. Arora was responsible for engineering design of the following: mechanical, electrical, plumbing, fire protection and life safety systems. Arora was also responsible for the development of the building information modeling (BIM) relative to each discipline. Arora contributed to the development of both the BIM execution plan and BIM standards for the project.

The design of a 15,000 SF Rail Vehicle Maintenance Storage Facility was also included with the project. The facility features a seven-track car shop for the light rail vehicles used on the Green Line. This project aimed to provide additional shop space for the larger number of vehicles that will provide service on the expanded system. The new car repair facilities included inspection pits, a wheel lathe, and vehicle wash facilities. Building services included compressed air systems in addition to conventional heating and plumbing systems. A radiant floor heating system was designed to provide a comfortable working environment for shop personnel. The project also featured office space for the maintenance facility’s administrative support staff and a parking garage for employee cars and MBTA trucks was located over the rail vehicle storage yard to maximize real estate utilization in a congested urban location.

This important project greatly improves public transit service in some of the most densely-populated municipalities in Massachusetts. Among its many benefits, the Green Line Extension Project: Provides new and better opportunities for residents and visitors to travel within their communities and within the region; provides environmental benefits by reducing the number of vehicles on the road; and support municipal plans for sustainable growth and development.

While the overall program ran into budget issues and as a result, corresponding schedule delays, the Design Team JV met the design and submittal schedules set by the MBTA’s team. The team did so within the allocated and authorized budgets. The MBTA temporarily halted the project to terminate the contracts of the PM/CM and construction team members, however, the Design Team JV was retained and was trusted by the MBTA to evaluate and redefine the program as a Design/Build project.


Massachusetts Bay Transportation Authority


East Cambridge, Somerville, and Medford, MA

Key Facts

LEED Silver Certification (Vehicle Maintenance Facility, In Progress)