Union square

Green Line extension to Union Square will open March 21, MBTA says

The long-awaited extension of the Green Line to Union Square in Somerville will open for passenger service on the afternoon of March 21, MBTA Chief Executive Steve Poftak announced Thursday.

New stations in Lechmere and Union Square will welcome passengers that day, marking an important milestone for the Massachusetts Bay Transportation Authority, which has been discussing expanding the Green Line for decades.

“It’s a really proud moment for the T, a really important moment for the region, and really a symbol that we can do great things and we can get things done,” Poftak said at a meeting of the MBTA Board of Directors.

The time of opening of The much longer Green Line extension branch to Medford, which includes five new stations, was tentatively scheduled for May but may not start carrying passengers until the summer.

The two branches, which cost the MBTA a whopping $2.3 billion, have faced a seemingly endless series of delays stretching back decades.

In 1990, the state promised to extend the Green Line to “Ball Square/Tufts University” as part of an agreement with the Conservation Law Foundation, a legal advocacy group, to mitigate the environmental impacts of the Big Dig, which buried Interstate 93 under the center of town. The foundation sued the state in 2005, accusing it of blocking the project, and settled in 2007 when the government agreed to complete it by 2014.

An interior view of the new Green Line train.David L. Ryan/Globe Staff

Further delays dragged the project down in 2015 when the budget hit $3 billion. Massachusetts considered removing it entirely. The MBTA cut costs and eventually won approval from its then-supervisory board to proceed with the project in 2017.

The 4.7-mile extension to Somerville and Medford began in 2018 with the aim of beginning passenger service at the seven new stations by December 2021.

But last year the MBTA pushed back the opening of the Union Square branch to March 2022, citing complications in the construction of its substations, and the delivery date of the Medford branch, which is winding down. at Tufts University, citing the supply chain impacts of the COVID-19 pandemic.

Despite the delays, transit advocates say they are excited to see the long-awaited project open to service next month.

The T expects shuttles to continue to replace Tube service between Lechmere and North Station until the day before service begins on the new branch, MBTA spokesman Joe Pesaturo said. last month.

Test trains have been running along the tracks since January 16.

Taylor Dolven can be reached at [email protected] Follow her on Twitter @taydolven.