Red Line (MBTA) - Operations and Signalling

Operations and Signalling

The line used trip-stop wayside signalling for the Ashmont and Harvard branches until the mid-1980s, while the Braintree Branch was one of the earliest examples of Automatic Train Control (ATC). The Alewife Branch was built with ATC, at which point the remainder of the line was upgraded to ATC as well. The line was under local control at towers until 1985 when an electromechanical panel was completed at 45 High St. This was replaced in the late 1990s with a software-controlled Automatic Train Supervision, using a product by Union Switch & Signal, subcontracted to Syseca Inc. (now ARINC), at a new theater at 45 High St. Subsequent revisions to the system were made internally at the MBTA.

The shortest scheduled headway ever run on the Red Line is most likely the 1 3⁄₄ minute interval in the schedule published in 1928. Ridership peaked on the line around 1947, when passenger counters logged over 850 people per four car train during peak periods. The newer ATC signalling was designed to higher safety standards, but the particular design of the block layout in the downtown area reduced the capacity by 50% over the previous wayside signalling system. The net loss of capacity measured in cars per hour has not been rectified, although at the same time the platforms were lengthened to run 6-car trains which are now operated on a longer headway. Additionally, the shifting between speed codes that is inherent in an ATC system near capacity caused peak period energy consumption to skyrocket, and accelerated the decline of the 01400 series fleet.

During snowstorms, the MBTA runs an empty train during non-service hours to keep the tracks and 3rd rail clear.