The Silver Line waterfront services (SL1, SL2, SL3, and SLW) charge the standard subway fare ($2.40 one-way as of 2024).
Express buses have a local portion within a community (which charge the local bus fare), and an express portion that takes a highway to or from downtown Boston (which charges a higher fare of $4.25 as of 2024).
Since 2018, the MBTA has been planning a major bus network overhaul, with implementation expected to be complete in 2028.
It is divided into two branches: Waterfront service (SL1, SL2, SL3, and the rush-hour SLW shuttle) that runs through the South Boston Transitway tunnel, and Washington Street service (SL4 and SL5) that runs on the surface via Washington Street.
[4] Seven routes – 52, 59, 61, 62, 67, 70, and 76 – serve more distant western suburbs including Bedford, Waltham, Lexington, and Needham.
They are descendants of routes acquired from the Middlesex and Boston Street Railway in 1972, which were subsequently renumbered using previously discontinued designations.
[5] As part of the implementation of the MBTA's Bus Network Redesign program beginning in 2024, the key bus route terminology is being phased out and replaced by a larger frequent route network.
The since-discontinued 136 and the 137 were briefly operated as far as Lowell and Lawrence, their original Eastern Mass terminals, while under MBTA control.
When the Red Line's Braintree Branch opened in phases in 1971 and 1980s, these routes were rerouted to terminate at the new rapid transit stations (principally Quincy Center).
They are the descendants of the Eastern Massachusetts Street Railway's Lowell–Boston route, which was inherited intact by the MBTA in 1968 and soon cut back to Burlington.
Two routes that run to Haymarket have weekend short-turn variants (labeled with a W suffix) that terminate at Wonderland.
The 500 series routes were created by the MBTA in the 1960s to take advantage of the newly constructed turnpike extension into Boston.