Crossing Signals

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Steve Bryan

Crossing Signals

Post by Steve Bryan » Fri Jan 13, 2006 7:47 pm

I am curious about railroad crossing signal circuits. Do they use relay logic or do they use plc's or some other type of controllers?

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rrnut282
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Post by rrnut282 » Wed Jan 18, 2006 8:36 am

The ones installed today use what looks like a PLC, with special programs and circuitry. The basic models use the three track sections to operate. As soon as a train crosses over the insulated joint the crossing signal is activated. The deluxe models use high frequency signals sent down the rail. By comparing the timing of the "echo" and the doppler shift of the frequency of the returned signal the controller can drop the gates at the proper time whether the train is crawling or flying. The ones I've seen installed lately have all been the latter.
rrnut282
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Rob
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antennaes at grade crossings.

Post by Rob » Sun Sep 10, 2006 8:57 am

Anyone know what the antenna is for on the newer( most of them) NS grade crossing shantys??
If its something for future use or something current or what?
I have no clue.
If needed, i can go grab a picture of one , but its usually right about dead center on the roof of the shantys.
I see them anywhere in kosciuosko county on the chicago district, and on the few NS replaced on the CF&E line, plus any newer ones on the Marion Branch, so im betting its a system wide NS thing from that.
Rob

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Greg46m
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Post by Greg46m » Sun Sep 10, 2006 12:03 pm

Rob, I don't know if it's connected, but I noticed there's a small little cell-phone type antenna magmounted on top of the CSX MCP shanty at St Joe. There's a tall MCP type antenna standing right there, but also this little magmount sitting on top of the shanty. I was confused when I saw that.

Mark
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Post by Mark » Sun Sep 10, 2006 1:49 pm

Greg46m wrote:I was confused when I saw that.
Perhaps you should not be around the rails while
you are confused. Sorry(not really), couldn't
resist.

Mark

caylorman
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Small Antennas on relay cases

Post by caylorman » Mon Sep 11, 2006 9:54 am

I asked a friend who is a signal maintainer on the Lafayette District what these were for once. He said that they sent out a low power signal when the crossing gates were not operating properly. I can't remember if it was when the batteries got to a certain level before they were fully discharged or what.

E.J. Caylor

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