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Green Line Extension (GLX)

Green Line train pulling into the Science Park/West End Station

The Green Line Extension (GLX) will extend the northern end of the Green Line from Lechmere to Union Square in Somerville and College Avenue in Medford.

  • Contract awarded: November 2017
  • Projected completion: Spring 2022
  • Budget: $2.3 billion
  • Status: Construction

GLX will provide service in areas that historically did not have access to fast and reliable public transit. By supporting an increased ridership of more than 50,000 trips per day, this project will significantly reduce vehicle emissions on the road.

Building a Better T

As part of our $8 billion, 5-year capital investment plan, we're renovating stations, modernizing fare collection systems, upgrading services for our buses, subways, and ferries, and improving the accessibility of the entire system.

Learn more

Project Features

  • A new Green Line branch on existing Lowell Commuter Rail tracks, from Lechmere to Medford
  • A new Green Line branch on existing Fitchburg Commuter Rail tracks, from Lechmere to Union Square in Somerville
  • The relocation and reconstruction of Lechmere station in Cambridge, plus six new additional T stations
  • A new vehicle storage and maintenance facility

View GLX stops on system map

Rider Benefits

  • Create additional transportation routes in the Medford and Somerville neighborhoods
  • Reduce the number of vehicles on local roads to improve traffic concerns
  • Support municipal plans for sustainability and urban redevelopment

What to Expect During Construction

An arial view of the new Lechmere Station, facing South.
Aerial view of the new Lechmere station, facing north toward the newly constructed Union Square and Medford Branches (August 2021)

green line Green Line Service Changes

Green Line service between North Station and Lechmere has been interrupted while crews work on the Lechmere Viaduct Rehabilitation in conjunction with Green Line Extension work.

During this time, dedicated inbound and outbound bus lanes along Charles River Dam Road connect Lechmere and North Station, providing continuous bus service for 14,000 Green Line riders.

Beginning Sunday, October 24:

  • B and C Branch trains will terminate at Government Center
  • D and E Branch trains will terminate at North Station

As GLX enters the testing phase, you may see trains running to Union Square while passenger service has not yet resumed. Check Green Line schedules and service alerts for current service information.

See service alerts for the Green Line

commuter rail Commuter Rail Service Changes

Commuter Rail service may shut down periodically along various portions of the Lowell and Fitchburg lines to support this work. Shuttles will replace trains during these times.

See service alerts for the Lowell Line

Bridge Closures

Construction near the following major bridges in Somerville has been completed and all four bridges have reopened:

LocationStatusSchedule
LocationWashington Street Bridge/UnderpassStatusOpenScheduleReopened May 31, 2020.
LocationBroadway BridgeStatusOpenScheduleReopened June 6, 2020.
LocationMedford Street BridgeStatusClosedScheduleWork is ongoing. Expected to reopen in spring 2022.
LocationSchool Street BridgeStatusClosedScheduleWork is ongoing. Expected to reopen in spring 2022. 

Learn more about bridge closures and detours

Past Events

View all events

Contact Us

For all questions and comments related to the Green Line Extension (GLX), please contact the GLX Project Team at info@glxinfo.com or 855-459-4636.

Recent Updates

View all project updates

Related Projects

four photos: two construction workers tamping down tracks, a person in a GLT hard hat directing a person in a wheelchair, a new green line train, and a green line trolley car full of riders heading to Park Street. There's a GLT logo banner at the bottom going across all four photos

This project is one of many we're working on to ensure twice as many passengers have access to a safer, more comfortable, and more reliable Green Line by 2030.

Learn more about the Green Line Transformation

Building a Better T

As part of our $8 billion, 5-year capital investment plan, we're renovating stations, modernizing fare collection systems, upgrading services for our buses, subways, and ferries, and improving the accessibility of the entire system.

Learn more

Recent Updates

View all project updates

Related Projects

four photos: two construction workers tamping down tracks, a person in a GLT hard hat directing a person in a wheelchair, a new green line train, and a green line trolley car full of riders heading to Park Street. There's a GLT logo banner at the bottom going across all four photos

This project is one of many we're working on to ensure twice as many passengers have access to a safer, more comfortable, and more reliable Green Line by 2030.

Learn more about the Green Line Transformation