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Quill Depot

Numbers and Letters on Signals?

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What do those numbers and letters on signals mean? Those little letters on the bottom of it. Is there a list somewhere? Thanks!

Edited by Quill Depot

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Well, I known D [insert number here] means if you are switching you have to go at that speed.

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I dont think those examples is what the poster is asking for...

 

BTW *Disclaimer* to any folks on the TO List DO NOT use those signals listed there as guides! I have already seen wording describing those signals if you used that on a Signals Quiz you would fail!

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What do those numbers and letters on signals mean? Those little letters on the bottom of it. Is there a list somewhere? Thanks!

 

 

I don't know of a list to decode them, but often it is either the track and chaining point (eg: A1 1334) or an indicator of which 'lever' on the interlocking machine controls this signal (eg: x 460).

 

Naturally, most interlockings no longer have machines with physical levers on them anymore, but the codes still remain as an indication of which switch is tied to the signal.

 

If I'm not mistaken, the signals displaying a chaining code (A letter and a number indicating track on top, numbers indicating distance on the bottom) are all "Automatic Signals", signals that are green unless there is a train occupying the area beyond the signal (also called the signal's "control length".

 

The signals displaying an "X" and a number on this plate (they may use other letters as well, but if so I am unaware) are generally "Home Signals", which are controlled by a tower somewhere, and regulate the movement of trains through an interlocking.

 

I find the guide GogiMet posted to be pretty good, although it doesn't quite decode the numbers. http://nycsubway.org..._Complete_Guide

 

As always please don't rely on a resource like this to study for any tests because neither I nor anyone else outside the MTA can verify it's accuracy - that said, in terms of gaining a general understanding I've found it very helpful.

Edited by itmaybeokay
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I dont think those examples is what the poster is asking for...

 

BTW *Disclaimer* to any folks on the TO List DO NOT use those signals listed there as guides! I have already seen wording describing those signals if you used that on a Signals Quiz you would fail!

 

Yeah almost all the definitions are wrong, but I guess it was more to make the regular railfan understand what's going on instead of just quoting chapter and verse out the rule book/policy instruction.
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The numbers are easy its a location of the track you will see 2 numbers one over the other like 120 50 this means the lenght of the track from where it starts is 12050 Feet the letters determine the track as 1 2 3 4 this is the basic of the numbers

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He's not looking at these to study, he's 12.

 

 

Im sorry I said anybody on the TO List....

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I don't know of a list to decode them, but often it is either the track and chaining point (eg: A1 1334) or an indicator of which 'lever' on the interlocking machine controls this signal (eg: x 460).

 

Naturally, most interlockings no longer have machines with physical levers on them anymore, but the codes still remain as an indication of which switch is tied to the signal.

 

If I'm not mistaken, the signals displaying a chaining code (A letter and a number indicating track on top, numbers indicating distance on the bottom) are all "Automatic Signals", signals that are green unless there is a train occupying the area beyond the signal (also called the signal's "control length".

 

The signals displaying an "X" and a number on this plate (they may use other letters as well, but if so I am unaware) are generally "Home Signals", which are controlled by a tower somewhere, and regulate the movement of trains through an interlocking.

 

I find the guide GogiMet posted to be pretty good, although it doesn't quite decode the numbers. http://nycsubway.org..._Complete_Guide

 

 

This also helps...suprisingly...

 

http://en.wikipedia.org/wiki/New_York_City_Subway_chaining

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This also helps...suprisingly...

 

http://en.wikipedia....Subway_chaining

 

To reprint the pertinent information (with something I just added in bold:

 

 

 

On the BMT and IND an odd numbered mainline track is going railroad south and an even numbered mainline track is going railroad north.

The local (usually outside) tracks on a given BMT/IND line are numbered 1 (south) and 2 (north). The express tracks are numbered 3 (south) and 4 (north). If there are an odd number of mainline tracks, the center track is (for example) track 3/4. The signals heading southbound will show the location as track 3 and northbound track 4. Additional tracks on the same chaining line are usually numbered higher by the same rules. On the four track BMT Brighton Line, the tracks from west to east are:

 

A1–A3–A4–A2

On the three track BMT West End Line, they are:

D1–D3/4–D2

On the two track BMT Canarsie Line, they are:

Q1–Q2

 

IRT practice

On the IRT the signals are numbered differently. The track number for chaining purposes is added to the end of the survey number, so that the southbound signal numbers end in 4 (local) and 2 (express) and the northbounds are 1 (express) and 3 (local). On a four track line, the signal numbers end:

4–2–1–3

On a three track line, 1/2 are used signals on the middle track (1 is for signals governing northward moves, and 2 southward). 4 and 3 are still the local tracks:

4–M–3

And on a two-track line, there are no express tracks, so the two tracks are:

4–3

Strangely, IRT track designations differ from the signal chaining track numbers they are numbered from left to right (facing north), tracks number 1 through 4:

1 - 2 - 3 - 4

And on a three-track line:

1–M–4 or 2–M–3

Thus, a line will have signal numbers ending in "4–2–1–3" and tracks designated as "1–2–3–4".

Signals on the IRT governing in the opposite of the normal direction of travel will have a signal number ending N+4 from the signal numbers governing in the normal direction.

 

Examples (On the signal plate, the "-" would be replaced by a line-break):

 

BMT:

B1-243 | B3-243 | B4-243 | B2-243

IRT:

2434-B | 2432-B | 2431-B | 2433-B

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