Quote:
Originally Posted by J. Will
Do all NYC subways have a front and back? Here the subways are reversible, so they don't have to turn around at terminal stations.
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When this happens, the motorman has to walk from one end to another, from car to car. That takes a few minutes, and back in the days when most of the NY subway system was built, trains came on ridiculously small headways at peak periods - 30 seconds, I've heard. If they had to wait for the motorman to walk down the length of a 12-car train, a bunch of trains would back up.
Early NY subway planners preferred to build loop stations so that trains could operate continuously. The older lines in Chicago have this, too - usually, there is a yard at the end of the line with a loop track in it. In NY, some lines terminated in Lower Manhattan, so they couldn't very well build a yard - they just built a loop-shaped station. City Hall and South Ferry both had this setup.
Most systems today - Chicago and Toronto included - don't have those ridiculous headways, so a simple pocket track at the end of the line works to turn trains around, and the motorman can do his walk.