At 03:34 AM 7/18/2013, Ravi wrote: >Hello all, > >Is there any method to detect an oncoming train about 2 KMs away? The method that appears to be used in Western Canada is to use=20 wires. A section of track is isolated electrically from the rest of=20 the track (easy to do - just insert a robust insulator between the=20 ends of the track section) and the train wheels bridge the circuit=20 when the train is present. This signal is used to cause the railway crossing lights to begin=20 flashing while the train is about a mile away from that=20 crossing. Another isolated track section is used to automatically=20 turn the flashing lights OFF after the train has reached, then left=20 the crossing. There were always lots of telephone poles and wires that ran parallel=20 to the tracks in Western Canada - I assume that was part of the CNCP=20 Telecom group stuff. I'm guessing that using one pair in one of=20 those cables was easy to do in those days. As a kid, I used to trick the crossing lights a mile away to begin=20 flashing by bridging the gap with a suitable conductor. As an adult,=20 I now know how annoying that would be. But the statute of=20 limitations on that misdemeanor has long since elapsed . dwayne --=20 Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax www.trinity-electronics.com Custom Electronics Design and Manufacturing --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .