Dan05979 1,028 Posted July 24, 2010 Share #1 Posted July 24, 2010 I was curiose to know how does a subway signal know a train has passed it, for example how does it know the entire set of cars has passed a green signal to let it turn red and then the brake trip arm lifts up? is it done by the weight of the train or magneticly? Any of you "buffs" know? Same thing with a speed sensitive signal, how does it know if your going to fast? I think its the gt signal with the white light? Link to comment Share on other sites More sharing options...
This topic is now archived and is closed to further replies.