The Winter Street Concourse is a pedestrian tunnel connecting the upper levels of the Downtown Crossing and Park Street subway stations in Boston, Massachusetts. It facilitates movement between the Green and Orange rapid transit lines operated by the Massachusetts Bay Transportation Authority, and consequently alleviates congestion on the Red Line. History The upper level of Park Street opened as part of the Tremont Street subway – a streetcar tunnel now carrying the Green Line – in September 1897. It was built as a cut-and-cover tunnel just below the surface of Tremont Street. From 1901 to 1908, the Main Line Elevated (now the Orange Line) shared the Tremont Street subway. In November 1908, the Main Line was moved to the parallel Washington Street tunnel under Washington Street. Similarly-constructed just below street level, it included a pair of one-way stations (Winter southbound and Summer northbound) one block southeast of Park Street. In March 1912, the Cambridge subway (now the Red Line) opened from Harvard Square to Park Street Under, one level below the streetcar platforms at Park Street. The line was extended (as the Dorchester tunnel) to Washington (a lower level at Winter/Summer, now Downtown Crossing) in April 1915, and to South Station Under in December 1916. The cut-and-cover tunnel was constructed with two levels from Tremont Street until halfway between Otis Street and Devonshire Street. The bottom level carried rapid transit trains, while the upper level (at the height of the existing Tremont Street subway and Washington Street tunnel platforms) was constructed as a fare lobby above Washington station and a potential pedestrian passageway east and west of the station. The section of upper level tunnel under Summer Street between Washington Street and Devonshire Street was used as planned as a fare lobby with entrances from Downtown Crossing department stores and as a turnstile repair area. The section between Tremont Street and Washington Street under Winter Street was leased as to adjoining businesses as storage space. In 1922 and 1927, it was proposed to be opened as a pedestrian passageway as part of expansion of Park Street station; the 1936-built expansion did not include the passageway. In 1960, the corridor was used for a temporary art exhibition – a forerunner of the Arts on the Line program. On March 9, 1979, the Winter Street section was opened as an inside-fare-control pedestrian passageway to ease demand on the Red Line. A ticket