Silver Line (MBTA)

The Silver Line is a bus route system in Boston and Chelsea, Massachusetts, operated by the Massachusetts Bay Transportation Authority (MBTA). It is operated as part of the MBTA bus system, but branded as bus rapid transit (BRT) as part of the MBTA subway system. Six routes are operated as part of two disconnected corridors. As of 2023, weekday ridership on the Silver Line was 27,000. The four Waterfront routes operate out of an underground terminal at South Station and run through the South Boston Piers Transitway – a dedicated bus tunnel through the Seaport District with stations at Courthouse and World Trade Center. At Silver Line Way, they fan out on the surface: the SL1 to Logan International Airport, the SL2 to Dry Dock Avenue, and the SL3 to Chelsea via East Boston. An additional short turn route, SLW, runs only at peak hours between South Station and Silver Line Way. The Waterfront routes use mostly articulated diesel hybrid buses with extended battery range. Two routes operate on Washington Street between Nubian station (at Nubian Square in Roxbury) and Downtown Boston. The SL5 terminates at Downtown Crossing and the SL4 on the surface at South Station. The Washington Street routes use articulated diesel hybrid buses. The Washington Street corridor was built to replace the Washington Street Elevated, which was used by the Orange Line rapid transit line until 1987. Initial plans called for a light rail branch of the Green Line, but trolleybuses and later CNG buses were substituted. Planning began in 1987 for mass transit to serve the growing Seaport; a new transit tunnel called the South Boston Piers Transitway was chosen in 1989. It was to run from Boylston to World Trade Center via Chinatown and South Station, though the Boylston–South Station section was later deferred as...