The long, depressing history of Green Line extension cost increases

Train tracks along the proposed MBTA Green Line extension in Somerville. The Boston Globe

The news that the Green Line extension into Somerville and Medford is up to $1 billion over budget may have been surprising, but it probably shouldn’t have been. After all, it’s a major infrastructure project supported by federal funding. It was also far from the first time the price of the project itself has increased in the last 10 years.

Here’s a quick look back at Green Line extension price points since 2005.

$438 million-$600 million

According to a state report looking into the project, $438 million was the early projected cost of extending the Green Line to both Union Square in Somerville, and to West Medford. (Other alternatives in the report were cheaper, but were less comparable to the current version of the project.) The report citing this figure was issued in the summer of 2005, and was first reported by The Boston Globe in May of that year. The $438 million number was based on 2005 dollar values, and the report was considered conceptual.


It was just another week before the Globe reported a new number: $559 million. Costs between $550 million and $600 million were used over the next several years. That may have been based on the $438 million figure, taking inflation into account to project years-of-construction terms.

$934 million

By 2009, as then-Gov. Deval Patrick’s administration sought to capture federal funds to help subsidize half the project, costs had increased to this new figure. Why? The project manager at the time told Tufts Daily (via the number had changed because the prior $600 million estimate “was generated from a very preliminary planning study.’’

The new number excluded the previously planned Route 16 station at the end of the line in Medford, stopping near Tufts University instead. Bringing the line to Route 16 was estimated to cost another $130 million that could come down the line.

$1.3 billion-$1.4 billion

The figure was cited by the state in applying for federal funds in late 2011. It included contingency money in the budget, and the submission also cited more than $200 million in expected finance charges. Some costs grew due to changes in the size of stations and a maintenance facility, though the state filing said some of the new costs could be offset with other budgetary adjustments.


In a June 2012 letter to then-Secretary of Transportation Richard Davey, the federal government put the overall cost at $1.34 billion based on the state’s submission. The figure was often reported as $1.4 billion.

$2 billion

Last September, Davey said costs had increased to just shy of $2 billion, with debt service upping it to $2.3 billion. According to State House News Service, the bump was due in part to new items added to the project—such as an extension of a bike and pedestrian path, and further structural work on the Lechmere Viaduct—as well as more pay for a contractor that took on greater responsibility.

Davey said the figure was really more like $1.6 billion, but that it included nearly $400 million in contingency money in case things went over-budget. This was the estimate by which the feds agreed to provide close to a billion dollars in funding.

$2.7 billion-$3 billion

The most recent increase is the steepest yet. Though the new estimate of up to $3 billion (not including financing payments) was made public this week, MBTA interim General Manager Frank DePaola said he had known costs had spiked since May. A general contractor, White Skanska Kiewit Joint Ventures, said the next phase of the contract would cost about $400 million more than previously expected. The state decided to take a new look at the rest of the costs and found that overall, the project is somewhere between $700 million and $1 billion over the previous budget.


While state officials have said canceling the project is one option to deal with the latest hike, they’ve also said it’s not a desirable one. The state plans to negotiate with the contractor and is otherwise looking to figure out how it may be able to get costs back down—for now, anyway.

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