MBTA Green Line extension

MBTA Green Line extension
Name	Green Line Extension
Type	Light rail
System	MBTA
Status	Operational
Locale	Middlesex County, Massachusetts
Start	Lechmere
End	Union Square / Medford/Tufts
Stations	7 new
Open	2022
Owner	Massachusetts Bay Transportation Authority
Operator	Massachusetts Bay Transportation Authority
Character	At-grade, elevated, and tunnel
Linelength	4.7 miles (7.6 km)

MBTA Green Line extension is a major expansion of the MBTA's Green Line light rail system into the cities of Somerville and Medford. The project, which opened in phases in 2022, extends service from a rebuilt Lechmere station along two branches terminating at Union Square and Medford/Tufts station. Conceived to fulfill legal commitments from the Big Dig project and to improve transit access in densely populated areas, the extension represents the largest expansion of the MBTA rail system in decades.

History

The origins of the project are deeply tied to mitigation requirements for the Central Artery/Tunnel Project, commonly known as the Big Dig. As part of a 1990 legally binding agreement with the Conservation Law Foundation and the U.S. Environmental Protection Agency, the Commonwealth of Massachusetts committed to extending the Green Line to alleviate traffic congestion and air pollution. Planning advanced slowly for years, with a major draft environmental impact statement filed with the Federal Transit Administration in the 2000s. The project faced significant challenges, including escalating cost estimates that prompted a major redesign in 2015 under the administration of Governor Charlie Baker. Following a financial and management restructuring, the project was approved for a Full Funding Grant Agreement from the Federal Transit Administration in 2021.

Project description

The extension adds 4.7 miles of new track, branching from the existing Lechmere viaduct. The main line follows the right-of-way of the Lowell Line commuter rail corridor, owned by the Massachusetts Bay Transportation Authority. One branch diverges to serve the Union Square neighborhood in Somerville, while the main branch continues north to Medford, terminating near the campus of Tufts University. The project included a complete reconstruction and relocation of the historic Lechmere station, moving it to an elevated position across from the CambridgeSide Galleria. Key infrastructure elements include the GLX Viaduct, the Washington Street Bridge, and a new vehicle maintenance facility.

Construction and timeline

Major construction began in 2018, led by the design-build joint venture GLX Constructors, a team comprising Fluor Corporation, The Middlesex Corporation, and Herzog Contracting Corp. The project was overseen by the Massachusetts Department of Transportation and the MBTA. The first phase, comprising the Union Square branch and the rebuilt Lechmere station, opened for passenger service on March 21, 2022. The second phase, extending service to Medford/Tufts station, opened on December 12, 2022. Construction involved extensive utility relocation, the installation of new overhead catenary systems, and the building of seven new stations.

Stations

The extension added seven new stations, all designed with full accessibility and modern amenities. On the Union Square Branch, the sole new stop is Union Square. The Medford Branch includes East Somerville station, Gilman Square station, Magoun Square station, Ball Square station, and the terminus at Medford/Tufts station. Each station features distinctive public art installations, canopies, and real-time passenger information displays, with designs developed by the architectural firm Sasaki Associates.

Service and operations

The extended line is integrated into the existing Green Line service matrix. The Medford Branch is served by the E Branch during peak hours, providing a one-seat ride to Northeastern University and Brigham Circle, while the Union Square branch is primarily served by shuttle services to Lechmere. The Massachusetts Bay Transportation Authority operates the service using its existing fleet of Type 8 and Type 9 light rail vehicles. The extension has increased daily ridership projections significantly for the MBTA system.

Impact and reception

The project has been hailed for improving transit equity and access in historically underserved communities within Somerville and Medford, areas previously reliant on bus routes like the 88 and 101. It provides a direct rail link to major employment centers in Kendall Square and Downtown Boston, and to institutions like Tufts University. Urban planners and local officials, including former Mayor Joseph Curtatone of Somerville, have emphasized its role in supporting sustainable development under plans like SomerVision. While the project's early cost overruns drew criticism from the Massachusetts Fiscal Alliance and state auditors, its eventual on-budget completion has been viewed as a major achievement for the Baker-Polito administration and the MBTA.

Category:MBTA Category:Light rail in Massachusetts Category:Railway lines opened in 2022