The 42nd Street Shuttle is a New York City Subway shuttle train service that operates in Manhattan. The shuttle is sometimes referred to as the Grand Central/Times Square Shuttle, since these are the only two stations it serves. The shuttle runs at all times except late nights, with trains running on two tracks underneath 42nd Street between Times Square and Grand Central; for many decades, three tracks had been in service until a major renovation was begun in 2019 reducing it to two tracks. With two stations, it is the shortest regular service in the system by number of stops, running about in 90 seconds . The shuttle is used by over 100,000 passengers every day, and by up to 10,200 passengers per hour during rush hours. The 42nd Street Shuttle was constructed and operated by the Interborough Rapid Transit Company (IRT) and is currently part of the A Division of New York City Transit . The shuttle tracks opened in 1904 as part of the city's first subway. The original subway line ran north from City Hall on what is now the IRT Lexington Avenue Line to 42nd Street, from where it turned west to run across 42nd Street. At Broadway, the line turned north, proceeding to 145th Street on what is now the IRT Broadway–Seventh Avenue Line. This operation continued until 1918, when construction on the Lexington Avenue Line north of 42nd Street, and on the Broadway–Seventh Avenue Line south of 42nd Street was completed. One trunk would run via the new Lexington Avenue Line down Park Avenue, and the other trunk would run via the new Seventh Avenue Line up Broadway. The section in the middle, via 42nd Street, was converted into shuttle operation. Through the 20th century, various attempts to convert, replace, or extend the shuttle have failed. The proposals have included conveyor-belt systems, as well as reconstruction of connections to the Broadway–Seventh Avenue and Lexington Avenue lines. One of the shuttle's trains was outfitted with automatic train operation on a trial basis in 1962, although the trial ended after a fire in 1964. A major reconstruction of the shuttle is ongoing between 2019 and 2022. The reconstruction allowed trains to be lengthened to six cars while also expanding both shuttle stations' capacity, and brought the shuttle into compliance with the Americans with Disabilities Act of 1990. The shuttle operates at all times except late nights,