Green Line B branch
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. 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 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.
, service operates on 8-minute headways at weekday peak hours and 8- to 12-minute headways at other times, using 9 to 15 trains.
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. While this route provided service to the fast-growing suburbs of Allston and Brighton, a more direct route was desirable. When Commonwealth Avenue was improved between Governors Square and the junction with Brighton Avenue in the mid-1890s, a -wide median was included for use by a streetcar line to support real estate development. Service began from Governors Square to Brighton Avenue, and along Brighton Avenue to connect with the older trackage at, on May 18, 1896.Further west, between and the Boston–Newton boundary at Lake Street, a -wide streetcar median was built. Service between Lake Street and downtown Boston began on August 15, 1896. Streetcars ran on Chestnut Hill Avenue, the existing Beacon Street line, Washington Street, and Huntington Avenue. At Lake Street, the line connected with the Commonwealth Avenue Street Railway, which had opened to Auburndale on March 26, 1896.
East of Governors Square, the Beacon Street line originally ran on Beacon Street, Massachusetts Avenue, and Boylston Street to Park Square. By the time the Commonwealth Avenue segments opened, streetcars continued along heavily congested tracks on Tremont Street to reach the northern railroad terminals. Both the Nonantum Square and Lake Street lines were rerouted into the Tremont Street subway to terminate at Park Street station soon after the tunnel's September 1, 1897 opening.
The Boston Elevated Railway leased the West End Street Railway on October 1, 1897, and continued its system expansion. The BERy opened new tracks on Commonwealth Avenue from Chestnut Hill Avenue to Brighton Avenue on May 26, 1900, allowing direct service from Lake Street to downtown via Commonwealth Avenue. Even though much of the land surrounding Commonwealth Avenue in Brighton was not yet developed, the new line was heavily patronized. For most of its length, the 1900-built trackage was not in a center median, but in a reservation between the southbound travel lane and southbound carriage lane. Between and Wallingford Road, the reservation was significantly wider than the tracks.
Growing service
The Commonwealth Avenue Street Railway opened the popular Norumbega Park on June 17, 1897. in 1904 and the Middlesex and Boston Street Railway Through service between Norumbega Park and Park Street station, operated by BERy east of Lake Street, begun on January 17, 1903. The Newton Street Railway began through service between Park Street and via the Watertown Line on February 23, 1903. When the Cambridge Tunnel opened in April 1912, the Waltham service was rerouted to Central Square station in Cambridge instead. On May 1, 1912, the M&B began a second through service over the Commonwealth Avenue route – this one running to Newton Highlands. The next month, two men were charged with a planned "conspiracy to blow up the tracks of the Elevated Company in Commonwealth av" using ten sticks of stolen dynamite.The Boylston Street subway opened on October 3, 1914, acting as an extension of the Tremont Street subway to just east of Governors Square, with intermediate stops at Copley Square and Massachusetts Avenue. Lake Street service via Washington Street was cut back to except at rush hours. The Newton Highlands through service was cut back to Lake Street, where it connected with BERy streetcar service. Norumbega Park through service continued to use the surface route, as the older M&B streetcars could not match the speed of the newer BERy streetcars in the subway. It took was split at Lake Street on November 1, with a connecting BERy line using the surface route; that was cut to a Kenmore–Park Street route on November 21.
On November 21, rush hour Washington Street service was cut back to Reservoir, leaving only Beacon Street cars using the Chestnut Hill Avenue tracks. Beacon Street service was cut to Reservoir on November 6, 1915, with Washington Street service extended back to Lake Street. Beginning on February 6, 1922, all Washington Street service was operated as a Brookline Village–Lake Street shuttle as part of service changes on the Huntington Avenue line. The Washington Street shuttle was converted to bus on April 24, 1926. It was redirected to Brighton Center on June 23, 1928, and eventually became route 65.
The Commonwealth Avenue line served two major baseball stadiums: Fenway Park near Governors Square, and Braves Field in Allston. The BERy opened a prepayment surface station at Kenmore Street in Governors Square in 1915. The new Braves Field opened on August 18, 1915; it included a loop track between Gaffney Street and Babcock Street with a prepayment station to allow streetcars to directly serve the ballpark. The loop was also used to turn trains for Red Sox games at Fenway Park, and for rush-hour short turns; after November 1945, these short turns also operated during midday and on Saturdays. The loop was heavily used during games; for the 1948 World Series, streetcars ran between Park Street and Braves Field on 45-second headways.
Further changes
Around 1916, the BERy built a storage yard for streetcars north of Commonwealth Avenue at Lake Street. Remaining M&B service to Lake Street was replaced by buses in 1930; the BERy replaced the old transfer station in the median with a new platform and waiting room in the yard on September 12, 1930. An expansion of Reservoir Yard, completed in May 1940, supplemented Lake Street Yard and eliminated the need to base some Commonwealth Avenue streetcars at Bennett Street Carhouse in Cambridge.In June 1922, the BERy proposed to operate the inner part of the Commonwealth Avenue line as a rapid transit service. Three-car trains of recently acquired center-entrance cars, which had higher capacity and shorter dwell times than older streetcars, would run on headways as low as two minutes at rush hour and four minutes at other times. A terminal stations would be built at Linden Street in Allston, where passengers would transfer between the subway trains and surface streetcar lines. The Lechmere Square in East Cambridge opened that July, but local opposition to the forced transfer caused the Linden Street terminal plan to be scrapped.
The congestion at busy Governors Square caused numerous delays to the streetcar lines. In May 1924, the state legislature directed the Metropolitan District Commission to plan an expanded rapid transit system in Boston, including an extension of the Boylston street Subway under Governors Square. The report, released in December 1926, called for the existing streetcar tunnels in Boston to be reorganized into two rapid transit lines with high-floor rolling stock. One line was to run from East Boston to Brighton, with the East Boston Tunnel realigned to connect with the Tremont Street subway near Park Street station. The Boylston Street subway would have been extended to Commonwealth Avenue, with a new station under Governors Square. A transfer station between the rapid transit line and the truncated Watertown and Lake Street surface lines was to be located at Warren Street between Commonwealth Avenue and Cambridge Street, near Brighton Center. Intermediate surface stops were to be located at Saint Mary's Street, Gaffney Street,,, and. Several busy grade crossings also were to be eliminated, and the report noted that the then-rapid growth along Commonwealth Avenue in Brighton might later justify extension of rapid transit to Lake Street.
The subway under Governors Square was projected to cost $5 million. The BERy and the city objected to this cost and proposed a $1.4 million plan where flyover ramps would separate Beacon Street auto and streetcar traffic from other traffic in the square. The tunnel was eventually chosen but construction did not begin until 1930, after the legislature lowered the cost that the BERy would pay to rent the subway from the city. Kenmore station and the new subway, which split to separate portals at on Beacon Street and on Commonwealth Avenue, opened on October 23, 1932. The extension was built to support future rapid transit conversion of the Commonwealth Avenue line, including extension of the underground section further west.
Interest in converting the Commonwealth Avenue line to rapid transit declined as focus shifted to expanding the subway to further suburbs. The 1945 and 1947 Coolidge Commission reports instead recommended a parallel rapid transit line along the Boston and Albany Railroad corridor, with local streetcar service retained on Commonwealth Avenue. However, several smaller improvements were made to the line. A siding was opened at on October 27, 1926, allowing trains to be short turned when necessary. On February 7, 1931, the Beacon Street and Commonwealth Avenue lines were extended to Lechmere, replacing shuttle services between Lechmere and various points in the subway. On June 30, 1931, the existing crossover west of Blandford Street was replaced by a pocket track, allowing temporary storage of streetcars there. It replaced the former surface cutback at Kenmore for subway short turns, which began on September 24, 1934. Around 1940, the Lake Street line was assigned route number 62 as part of a systemwide renumbering. On May 6, 1940, the line was reassigned from Bennett Street Carhouse to Reservoir Carhouse, eliminating the need for deadhead moves on Cambridge Street.