Green Line B branch
branch of the MBTA Green Line
The B branch, also called the Commonwealth Avenue branch or Boston College branch, is a branch of the MBTA Green Line light rail system which operates on Commonwealth Avenue west of downtown Boston, Massachusetts. One of four branches of the Green Line, the B branch runs from Boston College station down the median of Commonwealth Avenue to Blandford Street. There, it enters Blandford Street portal into Kenmore station, where it merges with the C and D branches. The combined services run into the Boylston Street subway and Tremont Street subway to downtown Boston. B branch service has terminated at Government Center since October 2021. Unlike the other branches, B branch service runs solely through the city limits of Boston. The Green Line Rivalry between Boston College and Boston University is named in reference to the B branch, which runs to both universities.
As of February 2023, service operates on 8-minute headways at weekday peak hours and 8- to 12-minute headways at other times, using 9 to 15 trains (18 to 30 light rail vehicles).
History
Initial construction
The first sections of what is now the B branch to open were built for what became the Watertown Line and Beacon Street Line. In 1889, the West End Street Railway opened the Beacon Street Line, including a branch that ran from Coolidge Corner to Oak Square along Harvard Avenue, Brighton Avenue, Cambridge Street, and Washington Street.
The public source identifies “Green Line B branch” as branch of the MBTA Green Line. This brief keeps that definition visible, then builds a research path around Green, Line and branch.
Why this record matters
A short description can identify a subject without explaining its stakes. For “Green Line B branch”, the useful work is to connect “branch of the MBTA Green Line” to the records capable of establishing context and consequence.
The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Sep 19, 2026. The linked authority identifier is Q172011. The first chronological checks are 2021, 2023 and 1889.
A concise general-reference account can conceal disagreements about scope, terminology or the weight assigned to individual sources. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Use the entry as an orientation point, then follow its citations and revision history. Names, dates and institutional relationships should be checked against the original record.
- Subject orientation
- Search vocabulary
- Locating named sources
The closest primary source, responsible institution and strongest cited specialist reference.
Three-step research path
- Establish the record: confirm the title “Green Line B branch”, its source revision and the description used here.
- Expand the search: follow Green Line B branch primary sources, Green Line B branch archive and Green research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “Green Line B branch”?
- Which cited source is closest to the event, object or claim?
- Which institution is responsible for the underlying evidence?
Search terms from this dossier
This entry incorporates text from “Green Line B branch” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.