How does a train run into signal problems?

[Tinamarie]

I'm always curious about this. How does a train run into signal problems and how do the signal problems get fixed?

[INDman]

Signals are very complex and alot of things can bother them and make them go all "screwy". A nice little feacher built into the subway signal system is that when something goes wrong, they go red and the trip arm goes up. That is unless a blub burns out. Fixing them is another story, they call in signal maintainers and they try to keep service going while work takes place.

[Zman]

I'm always curious about this. How does a train run into signal problems and how do the signal problems get fixed?

 

The same way you can run into a signal problem driving your car. You encounter it, wait for a bit (unless waived by by a police or traffic officer), pass it, then the DOT eventually sends someone out there to fix it if it cannot be reset by computer.

 

Same thing with us except that we need permission to pass the signal and have to pass it in a certain manner.

[LRG]

The same way you can run into a signal problem driving your car. You encounter it, wait for a bit (unless waived by by a police or traffic officer), pass it, then the DOT eventually sends someone out there to fix it if it cannot be reset by computer.

 

Same thing with us except that we need permission to pass the signal and have to pass it in a certain manner.

 

Which would be "to key by", correct?

[Eric B]

Most signal problems are "track circuits" where stuff like steel dust or water might short the circuit the block and make it read that the block is occupied.

[RTOMan]

Which would be "to key by", correct?

 

Correct from either RCC a Signal Maintainer or Supervisor on scene.

[Fresh Pond]

Correct from either RCC a Signal Maintainer or Supervisor on scene.

 

I don't wanna sound like a newbie but how does one actually 'key-by' without the actual use of a key?

[Y2Julio]

I don't wanna sound like a newbie but how does one actually 'key-by' without the actual use of a key?

 

# Automatic key-by. For an automatic or approach signal (not on the unresignalled IRT) indicating "stop", it is possible for the train to creep up very, very slowly, 1 or 2 mph, such that the front wheel of the train passes the track joint electrically separating signal blocks from each other, with still critical distance to spare between the stop and the train's tripcock. This maneuver, automatic key-by (AK), will drive the stop and hold it clear, and the train can proceed beyond the red signal prepared to stop within vision. Since the mid 1970's (when exactly?), this has not been permitted without special orders, on account of an accident resulting from abuse of "AK".

 

# Manual key-by. Some older signals on the IRT (and formerly the BMT) offer manual key-by, by which automatic and approach signals at "stop" can be passed by the train operator stopping the train and operating a key (hence the name) or key-by button physically on the signal or on a box attached to it, which drives the stop.

[Alex L.]

Y2Julio has just failed his Signal Test.

[Y2Julio]

Y2Julio has just failed his Signal Test.

Quoted from nycsubway.org. http://nycsubway.org/tech/signals/stops.html

[INDman]

Y2Julio has just failed his Signal Test.

 

May you provide the correct answer to the situation?

[Zman]

You have to stop on the circuit and watch the stop arm go down and stay down. Some signals have a 10 second delay before the stop arm goes down, so to key-by in the old style could very well cause an emergency brake application.

[Y2Julio]

You have to stop on the circuit and watch the stop arm go down and stay down. Some signals have a 10 second delay before the stop arm goes down, so to key-by in the old style could very well cause an emergency brake application.

Rule 2.40(m)

[INDman]

You have to stop on the circuit and watch the stop arm go down and stay down. Some signals have a 10 second delay before the stop arm goes down, so to key-by in the old style could very well cause an emergency brake application.

 

Ah, I thought that was implied when Julio said that you make sure that the stop arm retains. Oh well I knew that part of the key-by procedure.

[Alex L.]

Quoted from nycsubway.org. http://nycsubway.org/tech/signals/stops.html

 

Your cut and paste skills are beyond reproach; however, I take exception to the info you pasted, since it is only semi-correct (or semi-wrong, depending on your view).

 

# Automatic key-by. For an automatic or approach signal (not on the unresignalled IRT) indicating "stop", it is possible for the train to creep up very, very slowly, 1 or 2 mph, such that the front wheel of the train passes the track joint electrically separating signal blocks from each other, with still critical distance to spare between the stop and the train's tripcock. This maneuver, automatic key-by (AK), will drive the stop and hold it clear, and the train can proceed beyond the red signal prepared to stop within vision. Since the mid 1970's (when exactly?), this has not been permitted without special orders, on account of an accident resulting from abuse of "AK".

 

# Manual key-by. Some older signals on the IRT (and formerly the BMT) offer manual key-by, by which automatic and approach signals at "stop" can be passed by the train operator stopping the train and operating a key (hence the name) or key-by button physically on the signal or on a box attached to it, which drives the stop.

 

We do not differentiate between automatic key-by and manual key-by. There is only 'key-by' or 'No key-by'. Actually, there are three ways to get past a red automatic signal, depending on the presence (or absence) of associated fixed signs.

 

A red automatic with no additional signs can be keyed by getting permission from Control, then bridging the Insulated Joint with the first set of wheels, coming to a complete stop and observing the stop go down and stay down.

 

If the signal has a yellow AK plate (authorized key-by) (such as the ones on 2 Track at Stillwell Station) the procedure is the same but you do not need permission to key-by

 

If the signal has a red circle K plate (there's one at Dyre, the rest that i know are in relay positions), after getting permission from Control, pull up to the signal and Stop. Operate the Automatic Stop Arm Manual Release lever or button until the stop arm retains in the clear position.

 

If the signal has a yellow NO KEY BY plate, after getting permission, bridge the IJ with the first set of wheels, secure the train and step on the stop arm until it retains.

 

As you can see, AK stands for Authorized Key-by, not Automatic Key-by. After all, all Key-bys are automatic, since you can't key-by a home signal. What you describe as a Manual Key-by is actually identified by a fixed signal plate with a red circle K - no need for guessing.

 

Oh, and tripcock is a definite no-no. It is now properly called a car-borne tripping device.

[INDman]

Oh, and tripcock is a definite no-no. It is now properly called a car-borne tripping device.

 

Your sir are a wealth of great information, Thank you for your explanation. Now, is there any reason for elimination the use of "tripcock" or is it just lets change the name for the sake of doing something?

[Y2Julio]

 

Your sir are a wealth of great information, Thank you for your explanation. Now, is there any reason for elimination the use of "tripcock" or is it just lets change the name for the sake of doing something?

Probably someone complained about it being sexual or something.

[INDman]

Probably someone complained about it being sexual or something.

 

RIP America, the political correctness killed you.

[SubwayGuy]

Your sir are a wealth of great information, Thank you for your explanation. Now, is there any reason for elimination the use of "tripcock" or is it just lets change the name for the sake of doing something?

 

(Adaptation of a George Carlin routine)

 

"Gee can't imagine why they wouldn't want to use a perfectly good word like TRIPCOCK!"

 

Thanks for the explanation Alex. That was very informative.

[Eric B]

AK used to mean "automatic" keyby, back when you used to have many that were manual, and no permission was needed. Now, all of the ones requiring actual "keys" are long gone (that was way back in the early days of the IRT and BMT; hence why that definitions is wrong now), and there remain relative few you have to use the lever or step on it. So instead of putting signs on the automatic ones, they use the circle K or "No Key By" signs on the non-automatic ones.

So once permission was required for most signals, then, more recently, the freed-up "AK" designation was reinstated as meaning "authorized Key by".

[Y2Julio]

The stream of knowledge keeps flowing. Thanks Eric.:tup: