Even when it opens, South Coast Rail may never be completely 'finished.' Here's why.

South Coast Rail is a major feat of engineering and politicking that has taken decades to see through — the long-promised return of passenger rail to Fall River, Taunton and New Bedford. But what began as a promise in 1991 and which will carry riders to Boston in a little under a year is still “incomplete.”

What's opening in spring of 2025 is only Phase 1.

South Coast Rail has a second phase, known to the MBTA as the “Full Build.” It promises a faster, more direct, more environmentally friendly trip to Boston with more stations, including one at Fall River’s Battleship Cove — overall, a better product.

It may never happen.

Among the skeptics is Jackson Moore-Otto, the regional rail lead at the Boston public transportation advocacy group TransitMatters.

“I think maybe that’s a little bit bold to assume that there will be a Phase 2 without continued advocacy, just to be completely honest about the funding and political picture," he said.

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What is the South Coast Rail Full Build?

Phase 1 of South Coast Rail is an extension of the existing Middleboro/Lakeville commuter rail line. It takes a sharp turn west from Middleborough to the new East Taunton station, then in Berkley splits into two forks: one headed to New Bedford and one to Fall River.

The MBTA’s Full Build would connect the SouthCoast via Stoughton instead of Middleboro and use electric trains.

How is the Full Build different from Phase 1?

The Full Build is a straighter, faster, cleaner route. According to the Environmental and Energy Study Institute, among other sources, electric trains are cheaper to buy, cheaper to maintain, cleaner to operate, travel faster, and run more efficiently.

The Full Build contains more stations, too:

• two platforms in Easton

• a platform in Raynham

• a platform just outside downtown Taunton

• a second stop in Fall River at Battleship Cove, at the Gates of the City

So why didn’t we build that instead?

Money, time and a swamp. At its conception, South Coast Rail was supposed to follow the Stoughton route. But that route would also run through the Hockomock Swamp, an environmentally crucial and sensitive area in Raynham. In the late 1990s, environmental complaints about running diesel locomotives through it killed South Coast Rail for a time.

By the mid-2010s, the Army Corps of Engineers had given the OK to run electric trains through the region. It would also cost over $3 billion, which the state didn’t have, and take seven more years to build, which legislators didn’t think was acceptable.

So Gov. Charlie Baker’s administration decided in March 2017 to split the project into two phases. The first phase, at about $1 billion, would be much cheaper and (believe it or not) years faster to construct. It would give the SouthCoast at least some service to tide us over until the state could work on the second phase.

Is the Full Build in the works?

It’s hard to say. MassDOT has said it “views Phase 1 service as an interim service until the full service along the Stoughton corridor can be provided." The MBTA’s South Coast Rail website says “conceptual design work and preliminary engineering are currently underway.” It’s unclear if any new design work is being actively pursued, or if this refers to design work that’s already been performed.

In the past, MassDOT’s website has said we could expect the full build by 2030. That sentence is no longer on the website.

Will the Full Build ever happen?

Only time will tell. Moore-Otto says he's not confident, but it should happen.

"This was the first step in a multi-part promise," he said. “There will have to be continued advocacy at the local and state levels if we want to make good on the promises of ultimately improved service.”

Moore-Otto said he's optimistic that South Coast Rail's first phase will be successful, but said the area deserves even better. However, he noted, the T needs more stable income to pay for such a tall order.

"Given the current funding landscape and given the deferred maintenance needs of the T, unless we get a new stable source of revenue for the T, I don’t think that Phase 2 is going to happen," he said. “I don’t get the sense that it’s lined up for funding or being prioritized in a way that means it will be developed within the original timelines. That’s unfortunate.”

This article originally appeared on The Herald News: South Coast Rail: What is the Full Build, and will it be constructed?