| 
The MBTA's logo is seen on the side of an MBTA commuter rail locomotive in this file photo. Photo by James Sanna | Banker & Tradesman Staff
Electrification of the MBTA’s commuter rail lines has been a long-held dream for developers, riders and transit advocates, alike. And Boston residents could be first in line for a preview of what it could look like.
According to an RFP the MBTA posted Friday and first reported by Streetsblog Mass, the T is hoping to add battery-powered trains to the Fairmount Line, which connects South Station to Hyde Park via the core of Dorchester and Mattapan.
The RFP is in response to an unsolicited proposal from Keolis, the French company contracted to run the T’s commuter rail system, to run battery-powered electric multiple-unit trains on the Fairmount Line every 20 minutes on weekdays and every 30 minutes on weekends. That would bring the Fairmount Line close to the “regional rail” standard the MBTA’s former oversight board embraced in 2019, but more than half as frequent as most of the agency’s subways.
The RFP suggests the improved service could be underway as early as June 2026, when Keolis’ larger contract is due to be renewed or allowed to expire.
Any operator trying to beat Keolis’ proposal has until April 12 to respond.
Trains on the Fairmount Line only run every 45 minutes on weekdays and every 90 minutes on weekends, but neighborhood activists credit even this low level of service with dramatically improving transit access in Newmarket, Upham’s Corner, Bowdoin-Geneva, central Mattapan and Hyde Park, and some multifamily investors and affordable housing developers have used the line, launched under Gov. Deval Patrick in 2012 and given a frequency boost by Gov. Charlie Baker, to anchor their investments in the area.
While Mattapan Square is connected to the Red Line via a short light rail line, the rest of the neighborhood and much of the heart of Dorchester relies only on buses for transit.
The contract would also include building a maintenance facility for the new type of train, which the T hasn’t used before and which American transit agencies have very limited experience with. While the larger vision for a frequent, electrified commuter rail Transit advocates and MBTA officials have debated on whether to use these battery-electric trains when electrifying the commuter rail amid concerns about range, power infrastructure cost and the performance impact of heavy batteries compared to the well-understood overhead catenary wire technology traditional electric trains use. However, some fear overhead catenary wire would be politically difficult to build in some suburbs and it can be vulnerable to trees falling during severe weather.
