Fairmount Line's Morton Street station: The MBTA would deploy new Diesel Multiple Units (DMUs) on the Fairmount Line under a plan now under consideration within the Patrick administration. The new cars would allow for more flexibility to run more frequent service on the railway.

A recent Boston Globe article about the burgeoning public transit needs of the Seaport/Innovation District in South Boston focused on the state’s plans to add a new rail connection in that booming section of the city. The new service, the paper explained, would utlilize DMUs, a new, affordable rail car that could be in service in the Seaport District in as soon as two years.

Buried deep in the story, however, was a tantalizing nugget of information: The Patrick administration intends to spend roughly $100 million on buying DMUs for the Fairmount Line, which the Globe said “will get the new rail cars first.”

DMUs are Diesel Multiple Units – self-propelled cars powered by individual engines – that will replace the large locomotives like the kind that now run on the Fairmount Line. Patrick has hinted before in interviews that he thinks DMUs are a good fit for the line. State Secretary of Transportation Rich Davey is also a big proponent of the idea and word out of Beacon Hill is that the administration is moving closer to taking action this week.

Replacing the current rolling stock on the Fairmount Line with DMUs makes perfect sense. The DMUs would allow the line to pivot from its current hybrid role as a rapid-transit/commuter rail line into something closer to the Red or the Orange line. By eliminating the large and clunky locomotives that currently pull the commuter rail cars, the line will be able to run more like a subway line – fewer cars, but with more frequency. Critically, DMUs would offer the flexibility that the MBTA needs to add weekend service on the Fairmount Line, which now only operates Monday through Friday – a major weakness.

The DMUs can run on the existing right of way, without the need to tinker with bridges or platforms. And, without the behemoth locomotives at the front or rear, they will be less noisy as they roll through the neighborhoods— a major complaint of abutters. The state will need to create a new facility to maintain the cars, but that will be a worthwhile investment.

DMUs are now being manufactured in the United States for the first time, which will make their procurement by the MBTA cheaper and more efficient. They are already in heavy use elsewhere, particularly in Europe. But, they have not been heavily employed in the US for safety reasons. The newer generation DMUs are sturdier and will pass muster with federal regulators, clearing the way for their use here in Boston.

The DMUs probably won’t be in service until after Patrick leaves office. But an investment in this new technology by the governor and his team will add mightily to his legacy of achievements in our neighborhoods. The modernization of the Fairmount Line – and the opening of its cars to new communities in Mattapan and Dorchester – has been a decades-long dream of activists, and its potential economic impacts are profound. The Patrick administration has proven its commitment over the last six years by building new stations and making the improvements needed to take the Fairmount to the next level. The procurement of DMUs is the logical next step and we applaud the administration for its forward-thinking approach to the issue.

– Bill Forry