BOSTON (WHDH) -- A major MBTA expansion got the green light from Governor Deval Patrick on Monday.

The governor and other state officials kicked off construction for the first phase of the Green Line Extension project. They will rebuild two bridges and demolish a building to make way for new tracks.

Patrick said the expansion will benefit Boston and the surrounding communities.

“Green Line extension means expanded employment opportunity, housing opportunity and recreational opportunity. This project is about more than transportation, it’s about opportunity. It’s about growth,” said Patrick.

The expansion will extend existing Green Line service from East Cambridge to Union Square in Somerville and College Avenue in Medford.