IND Second System

Since the opening of the original New York City Subway line in 1904, and throughout the subway's history, various official and planning agencies have proposed numerous extensions to the subway system. One of the better known proposals was the "Second System", which was part of a plan by the Independent Subway to construct new subway lines in addition and take over existing subway lines and railroad right-of-ways. Though most of the routes proposed over the decades have never seen construction, discussion remains strong to develop some of these lines to alleviate existing subway capacity constraints and overcrowding, the most notable of these plans being the Second Avenue Subway.

The Triborough System was a proclamation for new subway lines to the Bronx and Brooklyn. These lines are the IRT Lexington Avenue Line, IRT Pelham Line and IRT Jerome Avenue Line. The Manhattan Bridge line described below later became the BMT Fourth Avenue Line, the BMT West End Line, the BMT Sea Beach Line, and the Nassau Street loops.

The route of the new subway ... comprises a main trunk north and south through Manhattan Borough on Lexington Avenue and Irving Place from the Harlem River to Tenth St. and on Broadway, Vesey and Church Sts. from Tenth St. to the Battery; two branches in Bronx Borough, one northeast via 138th St. Southern Boulevard and Westchester Ave. to Pelham Bay Park. the other northerly via River Ave. and Jerome Ave.. to Woodlawn Road, connecting with the Manhattan trunk by a tunnel under the Harlem River; a Manhattan-Brooklyn line extending from the North River via Canal Street across the East River on the Manhattan Bridge to connect with the Fourth Avenue subway in Brooklyn now being built, which thus becomes an integral part of the larger system; two branches southerly from the Fourth Ave. line extending south to Fort Hamilton and southeast to Coney Island; and a loop feeder line in Brooklyn through Lafayette Ave. and Broadway, connecting with the Fourth Ave. line at one end. and at the other crossing the Williamsburg Bridge and entering the Centre Street Loop subway in Manhattan which is thus also incorporated in the system.

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