MBTA Commuter Rail Maintenance Facility. The MBTA Commuter Rail Maintenance Facility (signed as, and often known by, its former name of Boston Engine Terminal) is the primary train maintenance repair facility for the MBTA Commuter Rail system. It is located in the Inner Belt area of Somerville, Massachusetts, near North Station in Boston. The present Commuter Rail Maintenance Facility was built in 1995, replacing the Boston Engine Terminal which was built by the former Boston and Maine Railroad.