Train stop

From Wikipedia, the free encyclopedia

A train stop is a mechanical or electrical device that stops a train if it attempts to pass a red signal, or if it attempts to pass at an excessive speed.

Most metropolitan railways, especially those with tunnels, have had some kind of train stop system, the mechanical ones on the New York subway, called trippers, being amongst the first.

[edit] Timed train stops

With a red signal, the train stop is raised and stops all trains that try to pass.

With a timed train stop, the train stop stays raised until the approaching train has shunted a track circuit on the approaching for a period of time corresponding to a set speed. If the train approaches at a speed higher than the set speed, the train stop will remain raised and trip the train to a stop. If the train approaches at a speed equal or lower than the set speed, the train stop will lower before the train arrives, and the train will be able to proceed without further hindrance.

Some timed train-stops require the driver to acknowledge a stimulus before being lowered on yellow signal.