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| What exactly is a signal problem? (1403873) | |
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| (1403876) | |
Re: What exactly is a signal problem? |
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Posted by Allan on Sat Jul 30 15:37:25 2016, in response to What exactly is a signal problem?, posted by jrr4 on Sat Jul 30 15:25:22 2016. There can be a few that I can think of:The signals/relays operate on AC power and a loss of AC power can cause the signals to go red and stop arms to go UP. A problem with a single signal where it isn't reacting to the relays and not changing when it should. A problem in a relay room where the electrical relay signals are not reacting properly. I am sure there are others. |
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Re: What exactly is a signal problem? |
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Posted by AlM on Sat Jul 30 15:51:23 2016, in response to Re: What exactly is a signal problem?, posted by Allan on Sat Jul 30 15:37:25 2016. I've been in front of a train when there was a "signal problem." The signal was red. The train crept up to the signal. Then ever so slowly (probably under instruction from the central command) the train operator moved the train forward past the red signal.Doesn't make for many trains per hour throughput. |
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| (1403881) | |
Re: What exactly is a signal problem? |
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Posted by Jackson Park B Train on Sat Jul 30 16:34:34 2016, in response to Re: What exactly is a signal problem?, posted by Allan on Sat Jul 30 15:37:25 2016. If memory serves, the signal wiring on the main IND trunks is the original with some minor changes--adding the 6th Ave express tracks, the Chrystie connections, 57th etc. Further, IIRC there was a fire involving a relay room on the 8th Ave line below W4th somewhere, and of course a similar issue at Bergen. NYCT is WAY behind in doing upgrades routine replacement of obsolete and no longer manufactured equipment. As a comparison, I have 2 Leicas from the 1930s. One still works, the other is no longer reliable--issues w/ the advance, shutter , etc. Given lack of Kodachrome, and the very few repairpersons who can actually service such antiques, they are retired. The digital toys become obsolete before they wear out... |
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| (1403923) | |
Re: What exactly is a signal problem? |
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Posted by gbs on Sun Jul 31 00:37:27 2016, in response to Re: What exactly is a signal problem?, posted by AlM on Sat Jul 30 15:51:23 2016. The t/o was "keying by" the signal, under proper authorization. Every automatic signal has a joint in the rail about 15 feet before it, and when the wheels of a train cross that joint the stop arm goes down, allowing the train to pass without tripping the brakes. This must be done at a very slow speed to give the arm time to go down after the wheel crosses the joint. Every safety system installed (either on the trains or on the tracks) is designed to stop trains or prevent them from starting, but each system must be able to be over-ridden or bypassed (always with proper authority), because a stuck train completely ruins service and must be moved out of the way. Examples: 1) the brakes on the train are essential to stop the train, but if they get stuck and don't release, the train can't move, so the brakes can be cut out if necessary. 2) the stop arm prevents collisions by preventing trains from getting too close to each other, but if an arm gets stuck in the up position, service stops, so trains can key-by. 3) trains can't start until the doors are all closed and locked and indication is passed to the t/o, but if indication is not passed for some reason and it can't be corrected en route, then indication can be by-passed and the train can move. Generally when these over-rides occur the train is taken out of passenger service, but at least it can be moved out of the way. |
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