The groundbreaking was held at the future site of Union Square Station in Somerville. Secretary Chao also announced the release of $225 million in federal funding for GLX, representing the second installment of federal support for the project.

“The Green Line Extension will improve access to education, housing and job opportunities across the entire MTBA system,” said Governor Charlie Baker. “Our administration is grateful for the collaboration and support we have received from Secretary Chao and all partners at the federal, state and local level to reach this milestone and begin a project that will have a transformational impact on this region of the Commonwealth by accommodating riders and spurring economic growth.”

“Residents across the region will benefit greatly from having expanded service in Somerville, Cambridge and Medford,” said Lt. Governor Karyn Polito. “The Green Line Extension is a key project in our administration’s work to increase transit options for travelers across the Commonwealth.”

“The Green Line Extension project will improve mobility, access to jobs, schools and the quality of life for tens of thousands of passengers in the Boston area,” said Secretary Elaine L. Chao.

“This is a terrific day for Somerville and Cambridge,” said Congressman Mike Capuano. “The Green Line Extension is moving forward and I look forward to the ribbon cutting.  I appreciate the effort and commitment of all our Green Line partners, especially the residents who have fought so hard to keep this project alive.”

“The Green Line Extension will bring long-awaited environmental justice, public health benefits, and economic development to our community. I’m thrilled to celebrate this milestone and remain committed to expanding access to public transportation throughout the Commonwealth,” said Congresswoman Katherine Clark.

The GLX Project will extend the Green Line approximately 4.7 miles along two branches from a relocated Lechmere Station in East Cambridge. Approximately one mile of the extension will run parallel to the Fitchburg Commuter Rail Line to Union Square in Somerville and approximately 3.7 miles will run parallel to the Lowell Commuter Rail Line to College Avenue in Medford. Seven new stations will be constructed as part of the project, including the relocated Lechmere Station, along with a new vehicle storage and maintenance facility in Somerville. Once completed, trains will operate every five to six minutes in the peak periods, providing fast and efficient service to downtown Boston.

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 that established the scope of federal participation in the GLX project. Under the FFGA, federal dollars will fund approximately $996 million of the revised budget of $2.3 billion.

“Today’s groundbreaking is another milestone in the concerted efforts it took in making GLX a reality,” said Transportation Secretary and CEO Stephanie Pollack. “Nearly two years ago, the Baker-Polito Administration hit the pause button to address GLX cost overruns, found ways to reduce the original design cost by one billion dollars, and led the effort to redesign the project. GLX project teams continue to meet with and facilitate input from stakeholders, including officials with the Federal Transit Administration, and other structural steps have been taken to bring us here to the site of what will be one of seven brand new stations. I want to thank the Baker-Polito Administration for its leadership, thank Somerville and Cambridge for financial contributions, and express appreciation to John Dalton and the GLX project team for their continued hard work in propelling GLX forward.”

“Just two years ago, many people thought this day would never come,” said MBTA General Manager Luis Manuel Ramírez. “But thanks to our federal, state, and municipal partners and a lot of hard work by a determined MBTA staff, we’ve made this project a reality.”

“Today’s groundbreaking signifies an important milestone for this project – and for the region,” said Somerville Mayor Joseph Curtatone. “With construction officially underway, the transportation, environmental, and economic benefits the completed Green Line Extension will bring to our communities are within our reach.”

The city of Somerville and the city of Cambridge have also exemplified their continued commitment to the GLX project with the contribution of funds, the first annual installment of which was received at the beginning of 2018. Both cities will make five annual payments with the City of Somerville contributing $10 million per year and the City of Cambridge contributing $5 million per year, totaling $50 million from the City of Somerville and $25 million from the City of Cambridge.

The Green Line Extension was procured through a framework that set strict limitations on the project’s total cost while allowing bidders to include additive options ensuring the MBTA could procure a project that maximized the benefits without jeopardizing its budget.  In addition to track infrastructure and seven station stops (including the relocated Lechmere Station), construction will include six additive options: platform canopies, additional elevators at select stations, public art, an extension of the community path with additional connections, and an enhanced vehicle maintenance facility.

In November 2017, the MBTA’s Fiscal and Management Control Board voted unanimously to award the design and construction contract to GLX Constructors, which is comprised of Flour Enterprises, Middlesex Corp., Herzog Contracting Corp., and Balfour Beatty Infrastructure.

The total project cost is approximately $2.3 billion, which includes other project components such as real estate, professional services, contingency, and procurement of 24 new trolleys to augment the existing Green Line fleet, the first of which is anticipated to enter service in fall 2018 with all cars anticipated to be complete by early 2019.

Design and pre-construction work, such as vegetation clearing and utility location along the right of way, is currently underway. Heavy construction is expected to start this fall with the project scheduled to enter the testing phase in late 2020 and the extension operational in late 2021.