The Green Line Extension is in the home stretch. Here’s an update on construction.

“From a big picture standpoint, we are right now at the eighty percent complete point, which is a long way.”

The MBTA Green line passengers with masks on a weekday morning during COVID-19 coronavirus pandemic. (David L Ryan/Globe Staff )

The Green Line Extension (GLX) into Somerville and Medford is 80% done, but there’s still a ways to go.

At a Wednesday meeting, the GLX team shared updates on construction progress and confirmed some long-anticipated opening dates. The Union Square branch will open this December as part of the D line, and the five-stop Medford branch will open in May 2022 on the E line.

GLX Program Manager John Dalton shared a little history about the project, noting that its main goal was to mitigate the environmental impacts of the central artery project, or Boston’s “Big Dig.” When the GLX is finished, 80% of Somerville will be within walking distance of rail transit, compared to the current 20%.


The GLX technically includes seven stations: an update to the existing Lechmere station, Union Square (its own branch), and then East Somerville, Gilman Square, Magoun Square, Ball Square, and Medford/Tufts. The project also included a new vehicle maintenance facility and community path extension.

“From a big picture standpoint, we are right now at the eighty percent complete point, which is a long way,” Dalton said. “We’ve come a long way — but these last twenty percent are not without challenges.”

Dalton shared a piece of good news about funding. In 2016, Cambridge and Somerville committed $25 million and $50 million respectively to help fund the project, to be paid in installments. The MBTA will be refusing the last few payments, Dalton said, and will likely return the full amount when the project closes next summer.

“Those two cities stepped up at a time that was critical and crucial,” Dalton said. “It’s a good news story to be able to say ‘thank you’ and ‘we’re fortunately in a position to not have to need it, and you’ll be getting it back.’”

Dalton noted they’re not out of the woods yet — the pandemic continues to impact supply chains and workforce availability. With much of the work behind them, the next step is testing and commissioning the systems.


“In the coming weeks and months, the public will begin to see Green Line trains running along the alignment,” he said. “For a while, that is going to be part of the testing process, so it will be very exciting to see trollies running on the Green Line Extension, but don’t immediately interpret that to mean we’re right on brink of opening the system to service, we’ll still be a ways away even when we see those trains running.”

Somerville State Sen. Pat Jehlen toured the East Somerville Station and a section of the community path, which she said had a great view of the city. Somerville State Reps. Christine Barber and Mike Connolly each shared their excitement for the opportunities the line will bring to the area, and cautioned a measured approach.

“We understand that as the GLX moves forward it is raising land values and creating additional displacement pressure,” Connolly said. “So, even after the project is done, we will need to address those issues. …We have to continue working to make sure the people who have waited for this for so many years get to stay in our community and enjoy the benefit of these transit improvements.”


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