The Metropolitan Transportation Authority (New York City) transit system operates trains using two-person crews consisting of a motorman and conductor. The conductor is located in the middle of the train and is responsible for opening the doors and closing them. When a train arrives at a station, the conductor verifies the train alignment on the platform by observing a black-and-white "zebra board" mounted to the platform wall or ceiling. When a train is aligned properly, the 6-feet long zebra board should be located directly opposite of the conductor's cab.