The system currently uses Automatic Block Signaling with fixed wayside signals and automatic train stops in order to provide safe train operation across the whole system.[211] The New York City Subway system has, for the most part, used block signallingsince its 1904 opening,[32][33] and many portions of the signaling system were installed between the 1930s and 1960s.
These signals work by preventing trains from entering a "block" occupied by another train. Typically, the blocks are 1,000 feet (300 m) long.[212] If no train is in the block, the signal will light up as green. When a train enters the block, the signal turns red, marking the block as occupied. The train's maximum speed will depend on how many blocks are open in front of it. However, the signals do not register a train's speed, nor where in the block the train is located.[213][214]
Subway trains are stopped mechanically at all signals showing "stop" aspects by automatic train stops located alongside the tracks; all cars are equipped with tripcocks. Although this is a simple principle of train stops, that wayside trippers must not be moved to trip ("stop") position until it is guaranteed that the train has fully passed the signal with all its cars.[212][215]
Today, the majority of all subway delays are caused by signal problems. Whenever a track circuit stops working, all of the signals which are affected by it turn red, as it is uncertain whether there is a train in that section, and the system properly reverts to a safe state.
Tradotto: sistema automatizzato con sussidio di operatore.
Poi se volete potete anche spiegarmi perchè fermare i binari e la corrente, che fastidio vi da il treno?