Track Circuits in NYP

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" onclick="window.open(this.href);return false;) 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!

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?

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.

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" onclick="window.open(this.href);return false;) 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?

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?).

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.