Boston Boston (), officially the City of Boston, is the capital city, state capital and List of municipalities in Massachusetts, most populous city of the Commonwealth (U.S. state), Commonwealth of Massachusetts, as well as the cultural and financ ...

's central subway is the system of tunnels through which the MBTA Green Line operates light rail transit (LRT or "trolley") service in the urban core of the city. The central subway comprises several tunnels built at different times, including the Tremont Street subway, the

Boylston Street subway The Boylston Street subway is a light rail tunnel which lies primarily under Boylston Street in Boston, Massachusetts. In operation since 1914, it now carries all four branches of the MBTA Green Line from Kenmore Square under the Back Bay into ...

, and the Huntington Avenue subway. Boston's subway operator, the

MBTA The Massachusetts Bay Transportation Authority (abbreviated MBTA and known colloquially as "the T") is the public agency responsible for operating most public transportation services in Greater Boston, Massachusetts. The MBTA transit network in ...

, sometimes also refers to the Red Line and Orange Line heavy rail tunnels as part of the central subway tunnel. In the early and mid twentieth century, the central subway was also known as the trolley subway, and was used for at least seven different trolley routes and with a variety of equipment. The original vehicles used were early single-unit electric trams with

trolley pole A trolley pole is a tapered cylindrical pole of wood or metal, used to transfer electricity from a "live" (electrified) overhead wire to the control and the electric traction motors of a tram or trolley bus. It is a type of current collector. ...

s to pick up the electric power from an overhead wire, which Boston had a decade of experience with. When the Tremont Street subway opened in 1897, it handled over 280 trolleys per hour and took nearly 200 trolleys per hour off the congested Tremont Street.

Frank Sprague Frank Julian Sprague (July 25, 1857 in Milford, Connecticut – October 25, 1934) was an American inventor who contributed to the development of the electric motor, electric railways, and electric elevators. His contributions were especiall ...

introduced electric multiple unit (EMU) trains in Chicago, also in 1897, and those came to Boston a few years later, not in the trolley subway but in the new "elevated", the

Boston Elevated Railway The Boston Elevated Railway (BERy) was a streetcar and rapid transit railroad operated on, above, and below, the streets of Boston, Massachusetts and surrounding communities. Founded in 1894, it eventually acquired the West End Street Rai ...

(BERy), which mostly served the West End. By 1901, Boston had the first EMU trains running underground, using some of the tracks and modified platforms of the Tremont Street subway. These heavy-rail lines evolved into the MBTA's Red, Orange, and Blue lines, which shared some of the central subway tunnels and stations with the light-rail Green Line. In 1908, a new Washington Street tunnel was opened, parallel to the Tremont Street subway from Haymarket station to North Station, for the heavy-rail BERy traffic, restoring the Tremont Street subway to light-rail-only operation.

References

{{reflist Green Line (MBTA)