Silver Line (MBTA) - History - The Silver Line

The Silver Line

The collection of services currently branded under the Silver Line umbrella have varying origins. The first section opened, known as Silver Line Phase I, was the line along Washington Street currently referred to as SL5; it is the ultimate product of community demands for restoration of local service after the Washington Street Elevated portion of the Orange Line was demolished in 1987. Proposals to build a new subway line under Washington Street or a new trolley line along Washington Street were deemed impractical, so the Orange Line was re-routed about 1/2 mile west onto the Southwest Corridor right-of-way, leaving many local residents without a rapid-transit option. Eventually, BRT was chosen to provide this service, and the MBTA feels it meets the needs of the communities affected by the Orange Line relocation. The line started running July 20, 2002, replacing service provided by the 49 bus (which had existed as a feeder route before 1987).

The tunneled section extending east of South Station, known as Silver Line Phase II, was constructed in conjunction with Boston's Big Dig and was originally referred to as the South Boston Piers Transitway. Tunnel sections were fabricated in a nearby, World War II–era dry dock and floated into place. Phase II opened on Friday, December 17, 2004, with the first route (Silver Line Waterfront) running only to Silver Line Way, temporarily using new electric trolley buses borrowed from the trackless trolley routes that have their hub in Cambridge, as not enough dual-mode buses were available initially.

When dual-mode buses were placed in service on December 31, 2004, two routes, dubbed SL2 and SL3, began service. As still not enough dual-mode buses were available, some rush-hour service was provided by CNG buses, with transfers at Silver Line Way. Through service was suspended after January 5, 2005, and was not brought back until March 5, with all buses dual-mode starting on March 14. Beginning on March 26, late night and weekend trips ran combined, running both around the BMIP loop and to City Point. SL3 ran to City Point via the Boston Marine Industrial Park; it ceased operation in 2008 due to insufficient ridership.

SL1 service to Logan Airport began on an interim basis on January 2, 2005. CNG buses ran on a Sunday-only (4 pm–10 pm only) shuttle route between Silver Line Way and the airport terminals. The agreement with the Massachusetts Department of Environmental Protection had called for airport service by January, but the MBTA did not yet have enough dual-mode buses for full service. Full-time SL1 service began on June 1, 2005.

For nearly five years after the opening of Silver Line Phase II, the two segments of the Silver Line were disconnected from one another. The MBTA wanted to connect the two via an underground tunnel, however the construction of this section, dubbed Silver Line Phase III, is no longer included in the region's long term plan due to funding concerns (see below for more details).

A partial solution that did not require a new tunnel opened on October 13, 2009, after fast-track construction using federal stimulus money. The new route, SL4, covers much of the same ground as the proposed Phase III in a dedicated bus lane on the surface that terminates across Atlantic Avenue from South Station, allowing a somewhat circuitous pedestrian transfer between Phase I and Phase II. When SL4 began operation, the existing Silver Line Washington Street service was rebranded SL5.