now shuttle track 1. Tracks 2 and 3 no longer exist, but the trackbed of track 2 can be seen inside the tunnel from passing trains on track 1. At the two terminals, the trackway for track 2 was occupied by platforms that formerly provided access to track 3, which was the former northbound express track. There was also a switch between tracks 1 and 3 just west of Grand Central station. The former northbound local track, track 4, was not connected to either track 1 or track 3. Track 2 was removed between the two stations in 1975, and circuit breaker houses have been constructed on the roadbed of track 2. Track 3, the former northbound express track, was taken out of service on November 7, 2020, then removed in 2021. Prior to the 2020 renovation at the Times Square station, in order to provide a connection between the platform for track 4, the former 43rd Street entrance, and the rest of the station complex, there was a pedestrian bridge over track 4. The pedestrian bridge could be temporarily removed to allow the train on track 4 to leave for maintenance on an as-needed basis. Track 1 is connected to the IRT Lexington Avenue Line's southbound local track south of Grand Central station. Track 4 connects to the IRT Broadway–Seventh Avenue Line's northbound local track north of Times Square station. With the removal of track 3, it remains physically impossible for a train to go from the IRT Lexington Avenue Line to the IRT Broadway–Seventh Avenue Line or vice versa by using the shuttle tracks. Operation The shuttle operates at all times except between midnight and 5:50 a.m. weekdays, and between midnight and 6:00 a.m. weekends, when alternate service is provided by the parallel . When 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 a motorman 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. Trains run on weekdays every