STV joined the Massachusetts Bay Transportation Authority (MBTA) to celebrate the opening of the Green Line Extension (GLX).

Revenue service has begun on the Union Square branch, the first of two segments to be completed on this $2.3 billion design-build.

STV serves as the lead designer for GLX as part of the design-build team led by Fluor Corporation/Middlesex Corporation/Herzog Contracting Corp/Balfour Beatty joint venture (GLX Constructors).

“It’s gratifying to see the impact this project will have on our communities,” said Keith MacKenzie, STV project manager. “Designing a public transportation project like this increases vital access to the educational, medical and economic institutions that connect our communities. STV is thrilled to have designed a system that will provide real opportunities for people for generations to come.”

The GLX design-build program includes the design and construction of a vehicle maintenance facility, an administration building, three traction power substations, a viaduct with more than 50 spans, seven stations, six bridges, and a community path with a pedestrian bridge.

The now-open Union Square Branch consists of two stations, the new elevated Lechmere Station and Union Square in Somerville. The branch is part of the larger 4.7-mile system that will ultimately provide the Massachusetts communities of Cambridge, Somerville, and Medford with a one-seat ride to downtown Boston.

The Medford Branch is scheduled to open later this year. 

The MBTA said it anticipates a number of benefits for GLX, including the reduction of 26,000 regional daily vehicle miles travelled. Daily ridership at the seven new GLX stations is expected to hit 45,000 by 2030.