Governor to Kick Off Phase I of Green Line Extension Tuesday

Gov. Deval Patrick will be in Somerville Tuesday to kick off the construction of Phase 1 of the Green Line Extension.

The governor will be joined by Rep. Michael Capuano, Somerville Mayor Joseph Curtatone and Massachusetts Secretary of Transportation Richard Davey, according to an announcement from the Green Line Extension team.

Phase 1 of the Green Line Extension consists of reconstructing two bridges and tearing down one building.

Workers will reconstruct the Medford Street railroad bridge in Somerville and the Harvard Street railroad bridge in Medford. Doing so will allow both Commuter Rail and Green Line trains to use the bridges. Crews will also knock down an MBTA-owned building at 21 Water St. in Cambridge, which will help prepare that area for the new Lechmere Station.

In other words, you won't see any trains or stations when Phase 1 is complete. You can read more about Phase I here.

Work on Phase 1 will cost $12.9 million, according to the Green Line Extension team's announcement. That's less than one percent of the total cost of the $1.3 billion Green Line Extension project.

Here are the other phases of the Green Line Extension project, along with their costs and projected completion dates (taken from this year-old document, which is already a bit out-of-date but gives a rough idea of the project's scope.)

• Phase 2 and 2A: Complete service to Washington Street and Union Square Stations. Cost: $340 million. Completion date: End of 2016.
• Phase 3: Construct new maintenance facility in Somerville's Inner Belt area. Cost $167 million. Completion date: End of 2017, early 2018.
• Phase 4: Complete service from Washington Street Station to College Avenue Station. Cost: $449 million. Completion date: Middle of 2018 (although that's an optimistic date; it is scheduled to be complete between 2018 and 2020.)
• Additional: Purchase of 24 new Green Line vehicles. Cost: $139 million.

The MBTA and Massachusetts Department of Transportation are seeking $557 million in funding from the Federal Transit Administration's New Starts program for the Green Line Extension. 

Tuesday's kick-off event takes place at 1:30 p.m. at 180 Somerville Ave. (in the back of the Target parking lot).