The Massachusetts Bay Transportation Authority uses a number of yards and facilities for maintenance and storage of its road and rail fleets.
Many of these facilities are former streetcar carhouses that were gradually converted to trackless trolley and bus use, although some like Southampton (built 2004) are of recent construction.
The subway lines each have one maintenance facility (except for three on the Green Line) and often several other yards used for overnight and midday storage. End-of-line tracks for temporary storage of trains are also present at Forest Hills (Orange Line), Wonderland (Blue Line) and Heath Street (Green Line); pocket tracks are present at Blandford Street and Northeastern University on the Green Line.
All MBTA Commuter Rail lines have a dedicated layover near the end of the line for trainsets to be stored overnight. Some provide ground power and other facilities; others are simply several yard tracks off the mainline. The MBTA has one heavy maintenance facility on the northside, plus two light maintenance facilities on the southside. Equipment is transferred between the two sides via the Grand Junction Railroad.