The T Second Avenue Local is a prospective rapid transit service in the B Division of the New York City Subway. It is proposed to run on the Second Avenue Subway in Manhattan and its route symbol will be . The first phase of the Second Avenue Subway opened in January 2017, from 63rd Street to 96th Street, and is served by the train. The full Second Avenue Line will be built in four phases, and the planned T service will not run until the third phase of the line opens from Houston Street to 63rd Street. Currently, the third phase is not funded or scheduled. From 1961 to 1968, the T and TT designations were also used for trains running along the BMT West End Line in Brooklyn, which was replaced by the train and later by the W. The West End Line is now served by the . Historical designation Original service The T designation was originally used for West End local and express trains in Brooklyn. The elevated BMT West End Line opened in 1916, replacing the original West End surface Line that opened in 1863 and branched off of the former Fifth Avenue Elevated. The BMT West End Line connected to the recently-opened BMT Fourth Avenue Line subway. The new elevated line's service was originally labeled 3 by the Brooklyn-Manhattan Transit Corporation (BMT). On June 24, 1916, 3 service began running between 18th Avenue and Chambers Street on the BMT Nassau Street Line via the Manhattan Bridge and the Nassau Street Loop. This service was extended to 25th Avenue on July 29, 1916 and Coney Island–Stillwell Avenue on December 23, 1918. On September 4, 1917, the first part of the BMT Broadway Line opened, and 3 service ran to 14th Street–Union Square. Chambers Street service was probably suspended until the remainder of the Nassau Street loop was completed. Service began running to the newly opened Times Square–42nd Street station on January 15, 1918. Service began running part-time to 57th Street–Seventh Avenue on July 10, 1919, and this extension was probably axed in 1920. The BMT Nassau Street Line and the Nassau Loop were completed on May 31, 1931. Weekday rush hour service and Saturday morning local resumed service from Bay Parkway or 62nd Street to Chambers Street running via the Montague Tunnel, and returning via the Manhattan Bridge south tracks. The Saturday morning rush hour local