The 42nd Street Shuttle is a New York City Subwayshuttle train service that operates in Manhattan. Part of a former Interborough Rapid Transit Company (IRT) line, it is sometimes referred to as the Grand Central / Times Square Shuttle, since these are the only two stations served by the shuttle. It runs at all times except late nights, connecting Times Square to Grand Central under 42nd Street. It is the shortest regular service in the system, running about 3,000 feet (910 m) in under two minutes. The 42nd Street Shuttle is part of the A Division of New York City Transit, and the tracks that it uses opened in 1904 as part of the first subway in the city. In order to distinguish it from the other shuttles in the system, NYCT Rapid Transit Operations internally refers to it as the 0 (zero). It has no above-ground stations, making it the only IRT service to remain completely underground during its entire run. Its route bullet is colored dark slate gray on route signs, station signs, rolling stock, and the official subway map.
The southbound express track on the four-track line was closed and new platforms were built, as the old station at Times Square had been local-only. However, the new arrangement turned out to be inadequate, and the shuttle was closed on midnight between August 3–4 for expansion of the platforms. The shuttle reopened on September 28, 1918, with improved passageways and platforms. On the walls of the stations, black bands (at Times Square) and green bands (at Grand Central) were painted to guide passengers to the shuttle platforms. As part of a demonstration for automation, the shuttle was briefly automated from 1959 to 1964 on Track 4. A severe fire at the Grand Central station destroyed the demonstration train and manual operation had been restored since.
The shuttle ran at all times until September 10, 1995. Since then, it has run at all times except late nights, where passengers alternately use the 7 train. When the shuttle is closed, the area is sometimes used for movie and TV filming. The French Connection and King of New York, among many other titles, were filmed on the 42nd Street shuttle.
Of the four shuttle tracks, only three are in use, the former southbound express track space being used for platform space at each terminal. The former southbound local track is now Shuttle Track 1. Track 2 no longer exists, however, remnants of Track 2 can be seen inside the tunnel from passing trains on Tracks 1 and 3. The former northbound express track is Track 3, and the former northbound local track is Track 4.
Tracks 1 and 3 are connected to each other and to the Lexington Avenue Line's southbound local track south of Grand Central station. Track 4 connects to the Broadway–Seventh Avenue Line's northbound local track north of Times Square station. There is no connection between tracks 1 and 3 on the one hand, and track 4 on the other; therefore, although the shuttle was once part of the original through-route of the first IRT subway, it is now physically impossible for a train to go from the IRT Lexington Avenue Line through to the IRT Seventh Avenue Line or vice versa by using the shuttle tracks.
In service, each of the shuttle tracks in operation at any given time is independent of the other; e.g., the train on track 1 simply runs back and forth on track 1, and there is no switching involved in reversing at each terminal. To provide for quick turnaround of the shuttle trains, there is an operator at each end of the train. Depending on which direction the train is traveling the operators swap jobs when the train gets to one end; one acts as the operator in the front and the other acts as conductor in the rear.
Note that this is a list of New York City Subway lines, which are the physical infrastructure over which services operate.
Lines with colors next to them are trunk lines; trunk lines determine the color of New York City Subway service bullets, except for shuttles, which are dark gray.