• Brooke Iglar

Green Line Extension Project Nears Completion

The upcoming $2.28 billion Green Line extension is nearing completion, with the new Union Square branch expected to open in December 2021 and the new Medford branch expected to be completed in May 2022. Construction on the extension began in 2018, with the old Lechmere station closing down in May 2020.

Photo Credit: MBTA

The Green Line is the oldest Boston rapid transit line and the third most heavily used light rail system in the United States, following the Metro Rail in Los Angeles and the Muni Metro in San Francisco. The line was assigned the green color in 1967 during a systemwide rebranding because several branches pass through sections of the Emerald Necklace of Boston.


The Green Line runs underground through downtown Boston, from the Lechmere Viaduct to Kenmore Square; it then branches out into four additional lines, the B, C, D, and E lines. These branches move above ground and run through western Boston.


In the new extension, which is being overseen by program manager John Dalton, the Green Line would continue north past the current Lechmere station in East Cambridgeinto two additional branches: one to Union Square in Somerville and the other to College Avenue in Medford, with four additional stops along the way. The Union Square branch will be a part of the D line, while the Medford branch will be accessed through the E line. This will expand the current Green Line by 4.7 miles.


Those four additional stations will be Washington Street, Gilman Square, Lowell Street, and Ball Square. The project will also oversee the construction of a new vehicle maintenance and storage facility, as well as a new Lechmere station that will be above ground and completely modernized.

Massachusetts Bay Transport Authority (MBTA) is working in conjunction with the Massachusetts Department of Transportation (MassDOT) to complete this extension.


Prior to its opening in December, trains will be tested on the Union Square branch of the Green Line for four months, beginning in August 2021. Testing on the Medford branch is expected to begin in the winter, ahead of its May 2022 opening.


From May 2020 to May 2022, the Lechmere and Science Park stations will be shut down for upgrades. During this time, shuttle buses will run along the same route as alternative transportation.


Construction has additionally led to the temporary closing of several bridges, requiring local residents to seek additional routes. Two, the Washington Street Bridge and the Broadway Bridge, have already opened, in May 2020 and June 2020 respectively. The Medfort Street Bridge and the School Street bridge will remain closed until Fall 2021.


In January 2015, a Full Funding Grant Agreement (FFGA), between the MBTA and the U.S. Department of Transportation Federal Transit Administration (FTA) was signed. Under the FFGA, the FTA will fund approximately $996 million of the $2.28 billion extension.


In 2016, Cambridge and Somerville committed $25 million and $50 million respectively to help fund the project; the MBTA plans to refund the full amount when the project closes next summer.

Despite earlier financial worries, the project is now expected to come in under budget. MBTA set aside $200 million of their budget for potential contingencies, with an additional $103 million provided by the American Rescue Plan. This funding from ARP was distributed to federally funded transportation projects to help cover additional costs and adjust for setbacks caused by the COVID-19 pandemic.


Due to the COVID-19 pandemic, the project was delayed by an estimated five months; the supply chain was impacted by COVID protocols and restrictions, as well as the construction workers.

Joe Aiello, the chair of the MBTA’s Fiscal and Management Control Board, has stated that any leftover money from the project will go to Somerville and Cambridge to help repay the funds they provided for this project.


The project will provide riders with a one-way trip from Somerville, Cambridge and Medford to downtown Boston, eliminating the need for bus and rail transfers at Lechmere Station and at Orange and Red Line stations and reducing travel time.


By supporting an estimated increased ridership of more than 50,000 trips per day, this project is also expected to significantly reduce vehicular emissions and traffic congestion. The project will additionally provide fast and reliable public transportation to areas that did not previously have it.

The extended Green Line is additionally expected to contribute additional business to these areas. As parking is typically hard to come by, the addition of a public transportation system will allow for easier access to local stores.


The project has raised some concerns regarding the potential gentrification of the neighborhoods it will be running through.


Since the development is receiving federal funding, it was required to perform an equity analysis to assess if it would have a racially discriminatory impact, or put a disproportionate burden on low-income riders. In May 2021, MBTA officials presented an equity analysis which found that, although the project would not negatively impact low-income or minority riders, the upcoming extension would disproportionately benefit higher-income, white riders.


It was noted that Somerville in particular has seen formerly blue-collar neighborhoods transformed by an influx of young professionals and new development in the years since state officials first committed to the Green Line extension. 80% of Somerville residents will live within half a mile from a transit stop once the project is complete, compared to the current 20%.


The Federal Transit Agency, which provided nearly $1 billion in funding, was informed of these findings, but given that the project is near completion, they determined that there were no practical alternatives or changes that could be made. The MBTA will instead attempt to mitigate the effects by continuing to run the 80 bus, which currently runs parallel to the planned Medford branch. Originally, officials had planned to remove it, forcing residents to pay a higher fee to ride the Green Line.