September 4, 1917, at 2 P.M., with an eight car train carrying members of the Public Service Commission, representatives of the city government and officials of the BRT, leaving Union Square toward Coney Island. Service opened to the general public at 8 P.M., with trains leaving Union Square and Coney Island simultaneously. The line was served by two services. One route ran via the Fourth Avenue Line and the Sea Beach Line to Coney Island, while the other line, the short line, ran to Ninth Avenue, where passengers could transfer for West End and Culver Line service. The initial headway on the line was three minutes during rush hours, three minutes and forty-five seconds at other times, except during late nights when service ran every fifteen minutes. On January 5, 1918, the line was extended north to Times Square–42nd Street and south to Rector Street. Express service via the line began, with Sea Beach and West End trains that had been running local becoming expresses. The opening of this portion of the line provided additional transit service to Times Square, with a new connection to Brooklyn. Local service henceforth ran between Times Square and Rector Street. Service was extended one station to Whitehall Street–South Ferry on September 20, 1918. The line was extended two stops northward to 57th Street on July 10, 1919. Express service between Times Square and Union Square was inaugurated on this date. Previously, express service terminated at Union Square, with local service terminating at Times Square. Express service then began to terminate at Times Square, with local service terminating at the new 57th Street station. Express service between Manhattan and Pacific Street began to run at all times except late nights. The line was extended to Lexington Avenue/59th Street on September 1, 1919. On August 1, 1920, the Broadway Line was extended on either end, with the opening of two tunnels under the East River. On the north end the line was extended through the 60th Street Tunnel to Queensboro Plaza, and on the south end the line was extended through the Montague Street Tunnel to DeKalb Avenue with service via the BMT Brighton Line. With these extensions, the Broadway Line was completed. Chrystie Street Connection reconfiguration On November 26, 1967, the Chrystie Street Connection opened, which is considered to be the most important expansion project undertaken by the New York City Transit Authority. The new