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Railroad Crossings

Posted by Anonymous

on Wed, Oct 19 2005 5:13 PM

I've always wondered this. What causes the lights and arms to activate at a railroad crossing? And how does the crossing know when the train is completly through the intersection?

Thanks,

Joe

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Posted by AC6000CW

on Wed, Oct 19 2005 6:27 PM

electric current flowing through the rails and if the train hit a certain spot it connects the switch and flows the energy back to the shack and the chips know to trun on the lights and arms and after the train comes through the fred signs a signal to the shack to lift up the arms.

http://www.railroadforums.com/photos/showgallery.php?cat=500&ppuser=5025

Posted by Anonymous

on Thu, Oct 20 2005 12:56 AM

Well you are right up to a certain point... The "FRED" has nothing to do with it. When the train passes the other end of the circut at most crossings it goes back up. The new ones can sense what side the train is on and the speed of it.. so it doesn't always need to be out of the circut for the arms to actuate back up. Most can tell when a train stops also.. incase there is not a need for arm actuation in certain circumstances.