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The first part of the Green Line Extension opens Monday. Here’s what you need to know.

"When both branches of GLX are open, 80% of Somerville's population will be within walking distance of a rail station."

The newer trains console/control operator's screen. David L. Ryan/Globe staff

On March 21, Green Line trains will rumble into Union Square for the very first time, a milestone in the decades-long Green Line Extension project.

Eventually, trains will head into Medford as part of the second phase of the project. But for now, Union Square in Somerville will be the first to see the new rapid train service.

Even just this portion of the project has taken longer than anticipated. The opening date was originally slated for October last year, but then was pushed to December. It was subsequently kicked forward to March.

The Medford branch of the extension is planned to open over the summer. In all, there will be six new stations, as well as a reconstructed and relocated Lechmere station. The new stations include Union Square on the first phase, plus East Somerville, Gilman Square, Magoun Square, Ball Square, and College Avenue stations as part of the second.


“It’s really exciting to see not only a project … that is going to be of a great benefit to our customers, but a project that was, frankly, dead, that essentially crashed and burned in 2015 and 2016,” Poftak said recently, according to The Boston Globe.

The Green Line is set to be extended to Union Square. – Globe staff


To get to the opening of the first new Green Line branch, MBTA officials have navigated many hurdles.

The history of the extension into Somerville dates back to 1990 when state officials announced it as part of a large-scale plan that included other transit projects for Boston 2020. The plan was to have the Green Line go beyond Lechmere to West Medford. There were also plans to extend the Blue Line. The cost for the Green Line project was estimated at $600 million at that time.

A hop, skip and a jump to 2005, and the advocacy group Conservation Law Foundation sued the state for delaying the project. The state set a 2014 deadline then.

In 2007, the project was delayed again for another couple of years. A delay of three more years was added in 2011. Construction began in 2012 with two bridge projects. Then, in 2015, contracts were cancelled with four firms, and the search for a new manager to monitor the project began. In December, 2016, it was announced that the new Green Line stations wouldn’t open until December 2021.

The last few years

The project made it through a time in 2015 when officials considered tossing it all together; the total cost of the project reached $3 billion. There wasn’t enough oversight, officials argued, according to the Globe. There were also problems with the bidding process and the timeline.


Then, in 2017, a new bid was awarded to GLX Constructors. The rebirth of the project really took place in 2018, according to the Globe. Construction began again with the idea of having all seven new stations, and the 4.7 miles of track, ready for December 2021.

The project was set at $2.3 billion, the current pricetag.

That, obviously, didn’t happen. The T announced last fall that the Union Square branch wouldn’t open until March this year.

“That’s unfortunate,” Poftak said at the time. “We really were looking forward to delivering this project in December. But we’ve faced a variety of challenges that have forced us to push the schedule out.”

It was a power substation that caused the delay, he said. The first delay, announced in June 2021, was due to the pandemic supply chain issues.

The substation, he noted, was near an elevated viaduct close to the Cambridge-Somerville border where the two new branches will part. The substation, he said, is the power source for Union Square. The size of the station made it difficult to work in.

“There’s only so many people who can fit inside that space and do productive, technically demanding work,” Poftak said at that time.


There are two more of them along the new Medford branch, he said. He hopes crews can apply new lessons learned to work on them.

“It is one of the challenges we are facing, and it is one of the areas that we are concentrating on as one of the critical path items,” Poftak said at the time. “If we’re not more productive and more efficient in building out these next two traction power substations, it is going to impact the schedule.”

Grand opening

A grand opening is planned for the extension at 11:30 a.m. on Monday. Massachusetts Department of Transportation Secretary Jamey Tesler, Poftak, and others are set to gather at the Lechmere Station in Cambridge.

The new Union Square stop at 50 Prospect Street in Somerville has already been added to the T’s spring train schedule, with the first train departing at 4:50 a.m. and the last at 12:36 a.m. during the week. There isn’t an MBTA parking lot or garage at the new station, although there are several public lots in the area.

But the hope, according to the MBTA, is for a large chunk of commuters to walk to the station and its forthcoming counterparts. “Union Station’s strategic location will contribute to an estimated removal of 26,000 private vehicle trips per day from local streets,” noted MBTA spokesman Joe Pesaturo. “When both branches of GLX are open, 80% of Somerville’s population will be within walking distance of a rail station. Today, that figure is only 20%.”


And for commuters hoping to stop for coffee during that walk, the nearest Dunkin’ to the new station is the one at 282 Somerville Ave., which is about a five-minute walk. For Starbuck fans, the nearest one is about an 11-minute walk to 180 Somerville Ave.

Departing Union Square and the new Lechmere station will require riders to now validate their CharlieCard or CharlieTicket before boarding. This includes tapping your ticket at one of the ticket machines and taking a receipt before boarding.

Branch 2?

While the Medford branch was planned to open in May, Poftak said in early February it’s likely to be summer instead. An exact date hasn’t been set. This branch includes the five new stations, terminating at the new College Avenue station.

“We’re still working to nail that down,” Poftak said at the time.


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