Track Circuits in NYP

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Track Circuits in NYP

Postby wfisher » Sat Jun 03, 2017 3:28 am

I'm seeing the following track circuit numbers in the NJ Transit data feed but don't really know how to interpret them. Using the track diagram here (http://rrsignalpix.com/tower_a/PennTrackLayout_sec.pdf) I'm able to piece together some of the movements but don't really understand the track circuits. Two examples of movements I don't get:

1. Look at platform 1 where there's switch 145. When trains head westbound, 145R is tripped. When trains head eastbound into the platform, 145P is tripped. What are those two circuits referring to exactly and what is R/P?

2. If you look to the top-left of that, you'll see double slip 139/143. I've seen 139R/139UN/143R/143N all tripped. What do these mean?

Any help would be appreciated!
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Re: Signals in NYP

Postby timz » Wed Jun 07, 2017 7:19 pm

Don't see any track circuits on that diagram. Aren't all the westward signals L for left, and eastward signals are R for right?
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Re: Signals in NYP

Postby OportRailfan » Thu Jun 08, 2017 10:04 am

timz wrote:Don't see any track circuits on that diagram. Aren't all the westward signals L for left, and eastward signals are R for right?


Correct. No track circuit names in that diagram, and that's the convention for signals in that 1972 track plan. FYI, switches are odd, signals are even, as were most track circuit numbers.
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Re: Track Circuits in NYP

Postby OportRailfan » Thu Jun 08, 2017 10:13 am

wfisher wrote:I'm seeing the following track circuit numbers in the NJ Transit data feed but don't really know how to interpret them. Using the track diagram here (http://rrsignalpix.com/tower_a/PennTrackLayout_sec.pdf) I'm able to piece together some of the movements but don't really understand the track circuits. Two examples of movements I don't get:

1. Look at platform 1 where there's switch 145. When trains head westbound, 145R is tripped. When trains head eastbound into the platform, 145P is tripped. What are those two circuits referring to exactly and what is R/P?

2. If you look to the top-left of that, you'll see double slip 139/143. I've seen 139R/139UN/143R/143N all tripped. What do these mean?

Any help would be appreciated!


What do you mean "tripped"? Are you referring to the switches, or signals returning back to stop?
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Re: Track Circuits in NYP

Postby wfisher » Thu Jun 08, 2017 10:11 pm

All I know is that this value is the "last identified track circuit ID for train."

You are right there are no track circuits in that diagram. When the train passes over switch 145, the feed shows "AA-145R" which means interlocking A, "circuit" 145R. I'm not sure if that's a physical portion of the track or, more likely, some code to represent that it's traversing switch 145 and the switch is locked into a certain position (R?).
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Re: Track Circuits in NYP

Postby OportRailfan » Tue Jun 20, 2017 9:13 am

wfisher wrote:All I know is that this value is the "last identified track circuit ID for train."

You are right there are no track circuits in that diagram. When the train passes over switch 145, the feed shows "AA-145R" which means interlocking A, "circuit" 145R. I'm not sure if that's a physical portion of the track or, more likely, some code to represent that it's traversing switch 145 and the switch is locked into a certain position (R?).


Yeah that has nothing to do with the track circuit IDs. All switches are odd, and while track circuits can be even or odd, they usually end in "T"; A83T, A99T, A101T, etc.
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