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CPL signals in the Subway?


Y2Julio

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Would implementing CPL signals simplify NYCT's signaling system? It sure would reduce the amount of signal heads required to display certain aspects at interlockings. Thoughts?

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Would implementing CPL signals simplify NYCT's signaling system? It sure would reduce the amount of signal heads required to display certain aspects at interlockings. Thoughts?

 

NYCT signaling is already exreamly simple. I don't know if you can really make it any simpler then it already is. Look at NORAC signals. It's ALOT more cOmplex.

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Should be able to use dwarf CPLs.

 

But why, people can't remember what the signals mean? If that's whats going on, they shouldn't have the job.

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NYCT signaling is already exreamly simple. I don't know if you can really make it any simpler then it already is. Look at NORAC signals. It's ALOT more cOmplex.

 

Exactly. The fixed-block concept is about as old as trains signals have been around; it's just inefficient or, perhaps, too simple nowadays where capacity dictates a more reliable and precise method to signal and coordinate train movement.

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Its not the signals, its stopping distance. If every GT and ST timed element signal was calibrated correctly and does what the sign says it will do, one will be amazed how many extra trains can fit out there. Also the Willie B incident couple decades ago highlighted stopping distance inefficiencies. Many ST signs clear much lower (or not at all in spots) then their posted because of that stopping distance issue the way it is today. They were fine with the old steel brake pads that threw everyone around when the train went into emergency braking. Nowadays emergency braking is basically a glorified full service brake (only a slightly shorter brake distance than a full service would provide).

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no need to change the current signal aspects...they work and the entire operations workforce has been broken in on them.

 

personally i find nyct's signals much easier to view AND understand than cpl's or NORAC

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or if not CPL signaling, how about CSS?

 

Why did the Transit Authority never adopt pulse code cab signalling along the likes of the PRR and LIRR?

 

Why change what has worked just fine for years. Julio, you keep asking why they never changed, but why should they?

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INDman

So why did they installed CBTC on Canarsie and planning on doing the same on Flushing, if the current system works fine in the rest of the subway?

 

I have a question though, Is CBTC is successor to Pulse Code Cab Signalling or completely different entity?

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Why change what has worked just fine for years. Julio, you keep asking why they never changed, but why should they?

 

CSS would be an improvement in NYCT if you ask me. Would reduce/remove signaling between interlocking, would be useful as a safety measure since automatically apply a penalty brake application to overspeeding until the T/o acknowledges the system by taking a brake application and at the same time protect the train ahead in the block by dropping code until the train behind it gets zero code and can't move forward.

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CSS would be an improvement in NYCT if you ask me. Would reduce/remove signaling between interlocking, would be useful as a safety measure since automatically apply a penalty brake application to overspeeding until the T/o acknowledges the system by taking a brake application and at the same time protect the train ahead in the block by dropping code until the train behind it gets zero code and can't move forward.

 

I don't think CSS is any safer then the current signal system already in use. I think any system wide upgrade would be focused more on moving block systems that would increase track capacity. Right now there only the (7) line will be upgraded with a system similar to that of the (L) line, but they will not be compatible. If anything, the smarter move would be to go back to "old fashioned" relay systems since there have been many problems with CBTC and "solid state interlocking" such as the one at Bergen St on the IND which crashes almost on a regular basses.

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For anyone who doesn't know what a CPL (color position light) looks like, here's an example of a dwarf signal (small size)

 

dwarf12lightfront.jpg

 

The circular structure contains block information: A red horizontal -- means stop (no blocks clear), a yellow diagonal / means approach (1 block clear), and a green | means clear (2 or more blocks clear)

 

The 6 white lights around the main head modify the signal's meaning by conveying speed information:

 

cplprimer2.jpg

 

cplprimer3.jpg

 

 

This kind of signal is not really the most practical for the subway because of the space it takes up, the short blocks of the system, the amount of heads needed for each signal, and the need to convey more accurate route info. The reason the SIR uses it is because it used to be owned by the B&O, and is a more appropriate place for this kind of signal. More info about this kind of signal can be found here

 

 

With regard to cab signalling, I have to agree that it would cause more problems than it would solve. There is no reason to switch over from the current system, and as INDman said, the implementation of newer technology always seems to have something go wrong. This is not even considering the cost of upgrading the rolling stock and many other components

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red=stop

yellow=slow down/go slowly

green=go

 

not rocket science

 

Heres the Kicker..

 

What do they "mean"?

 

You say that on a signals quiz you would fail it, oh wait some have and guess what? They arent Train Operators..

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red=stop

yellow=slow down/go slowly

green=go

 

not rocket science

 

Not quite that simple.

 

Red: Stop

 

Yellow: The block you're entering is clear but the block after it is not, so be prepared to stop at the next signal (go slow implied there but not explicit)

 

Green: This block and the one after it are clear, proceed at speed limit

 

Red over white: one-shot grade timer (GT), usually preceded by a tag saying GT/xx (xx is the timed approach speed in MPH). Clears to yellow or green if you're at or below speed, otherwise trips you.

 

Yellow over a black placard saying "S": two-shot GT, next signal is red. Approach at or below speed to clear it, get tripped if you don't.

 

Red over red: Stop

Yellow and green aspects at the top of a home signal retain the meanings I described above as do GTs and other specialized signals.

 

At the bottom of a home signal, yellow indicates that you'll be proceeding along a diverging route while green indicates that you'll be proceeding along the main route.

 

And there are probably other aspects that I either don't know or forgot to mention here that can be and are indicated on a regular basis. While it's not quite rocket science it's not simply a set of upside-down traffic lights either.

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Red: Stop

 

Yellow: The block you're entering is clear but the block after it is not, so be prepared to stop at the next signal (go slow implied there but not explicit)

 

Green: This block and the one after it are clear, proceed at speed limit

 

If this was a MTA RTO Signals quiz you would fail as well,just saying...:)

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Thanks; just out of curiosity, what did I miss?

 

From the Rule Book.

 

Red=Stop Call Control Center(If there isnt a train visible in the area and you are waiting for two minutes rule of thumb)

 

Yellow=Proceed with Caution be prepared to stop at Next Signal.

 

Green=Proceed..

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Thanks; just out of curiosity, what did I miss?

 

AUTOMATICS:

 

Red automatic - stop 15 feet before the signal and call

Yellow automatic - proceed with caution, expect the next signal to be red and be prepared to stop before it

Green automatic - proceed at the allowable speed

 

HOME SIGNALS:

 

Red over red - stop and stay

Green over green - proceed at the allowable speed on the main route

Green over yellow - proceed at the allowable speed on the diverging route

Yellow over green - proceed with caution on the main route, expect next signal to be red and be prepared to stop for it

Yellow over yellow - proceed with caution on the diverging route, expect next signal to be red and be prepared to stop for it

Red over red with yellow "call on" aspect - stop, operate manual release lever, proceed with restricted speed and extreme caution, prepared to stop within 1/2 the field of vision

Three yellows - yard indication aspect...switches are lined to take you into the yard. Can also be used to indicate uncommon moves such as crossing over multiple track switches from say a southbound local to a northbound express track.

Yellow on a DWARF signal - proceed with restricted speed and extreme caution, prepared to stop within 1/2 the field of vision

Red on a DWARF signal - stop and stay

 

and of course that says nothing about timed signals, fixed signals, wheel detectors, etc....

 

its a simple system but the wording is key. i still think its a lot simpler than NORAC which gives you all these signal aspect names but the indications don't follow logically to me...."medium approach" vs "approach medium" vs "medium approach medium".

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its a simple system but the wording is key.

 

Which has tripped up College Grads on the Signals Quiz the Wording...

 

They didn't make the cut either...

 

You run a Automatic you will be shocked to see how many rules you violated when you see your DAN...

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Yellow over a black placard saying "S": two-shot GT, next signal is red. Approach at or below speed to clear it, get tripped if you don't.

It's a white stencil (on newer ones, an array of LED's), and it's approach at or below speed to clear "it" meaning that next signal; if you don't then you get "penalized", meaning you have one more chance (your second "shot") to slow down enough (now an even slower "penalty time" speed) before being tripped.
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