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What’s going on with the Green Line extension project?

Train tracks along the proposed MBTA Green Line expansion area in Somerville.Aram Boghosian for The Boston Globe/Globe Freelance

The plan to extend the Green Line into Somerville and Medford is facing a major hurdle after MBTA officials disclosed this week that they may need between $700 million and $1 billion more to finish the project, which would add nearly 5 miles of trolley track, six new stations, and relocate an existing one.

Why did the price tag go up?

T officials vastly underestimated the project’s price in part because engineers the agency hired based their calculations on prices of large T projects completed during the recession, according to Transportation Secretary Stephanie Pollack.

Officials also said another reason costs are higher than expected is that they are using a new contracting process for the project that requires the T to negotiate the price of each portion of the multiphase project as they go along.


Can anything be done to lower costs?

Officials said they are looking into various options now, including downsizing and simplifying the design of stations, cutting back on a planned walkway and bike path, and making changes to plans for a maintenance and storage facility along the extension.

The agency is also considering trying to find additional state funding to cover the costs and may turn to private partners for funding aid. The T could also seek a new contractor to finish the project for less.

Could the project be delayed or even canceled?

Officials said they are not ruling out the possibility of scrapping the project altogether, even though they’ve already spent several million dollars and would face additional expenses if they give up on it entirely.

If the project isn’t canceled, it will likely be delayed — another in a series of setbacks it has seen over the years.

In the 1990s, the state committed to the Green Line extension as a measure to offset the Big Dig’s environmental impact and set 2011 as the deadline to finish the project. Work did not begin until 2013, however. The first three stations of the project are now due to open by 2017 and the other four by 2020.


What are the next steps?

State officials will now weigh various options to either reduce costs or secure more funding or a combination of both.

The state is also seeking public input through Sept. 9. To share your thoughts with the MBTA and the state Transportation Department, e-mail: and

Nicole Dungca can be reached at Follow her on Twitter @ndungca.