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Jan 31, 2012 10:03:36 GMT
Post by programmes1 on Jan 31, 2012 10:03:36 GMT
Can someone clear up for me what the difference is between the following:
signal remaining at danger and
signal failing to clear.
I have seen it used but no description was used to define the difference and the same thing happens surely.
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Jan 31, 2012 10:54:30 GMT
Post by citysig on Jan 31, 2012 10:54:30 GMT
To be honest, it is a hair-splitting exercise used within the reporting process to highlight what has actually failed. As such, the terminology tends to slip into delay reasons.
Generally, it separates / distinguishes between whether the signal that has failed is either a controlled or automatic signal.
An automatic signal - aspect usually clear - when failing becomes a "signal remaining at danger." That is, it is not returning to its usual aspect.
A controlled signal - aspect usually danger - when failing becomes a "signal failing to clear."
To most people, they both mean the same thing, and that is a signal failure.
A similar set of politics governs points problems. As a controller, I "should not" encounter a "points failure" but instead will see a "signal failing to clear." It is not for us as mere controllers to decide whether the points are at fault and are the reason for the signal failing - even if our years of experience tells us that the points not being fully reversed/normal means the signal won't clear ;D
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Jan 31, 2012 14:11:59 GMT
Post by charleyfarley on Jan 31, 2012 14:11:59 GMT
Although this is a London Overground situation, what type of signal is it that remains at red until a minute or so before a train is due (10 minutes frequency). Seen repeatedly at the same location.
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Jan 31, 2012 17:26:24 GMT
Post by causton on Jan 31, 2012 17:26:24 GMT
It is perhaps difficult to explain the nature of failure to anyone outside the industry, especially as the generic advertised failures are most often the result of another kind of failure entirely. Failures can be mechanical, electrical, pneumatic or other and other includes animals, insects, inanimate objects, weather etc! Oh, people will always say a problem is one thing when if you look at it, it turns out to be another. Worked in a shop where a colleague said 'The price of that shoe is wrong!' - no, it turned out he was resting the barcode scanner on a sheet of labels and scanning something extra whenever he put the scanner down, oblivious to the beeping... Interesting distinction between the two types of failure though  |
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Jan 31, 2012 19:54:45 GMT
Post by norbitonflyer on Jan 31, 2012 19:54:45 GMT
Although this is a London Overground situation, what type of signal is it that remains at red until a minute or so before a train is due (10 minutes frequency). Seen repeatedly at the same location. I would guess the signal protects a junction or level crossing normally set for a conflicting move, and cleared only when a train approaches. |
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metman
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Jan 31, 2012 22:53:36 GMT
Post by metman on Jan 31, 2012 22:53:36 GMT
Sounds like a semi-automatic signal. In LUL terms it would have the local IMR/cabin letters and then a number.
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Feb 1, 2012 7:17:47 GMT
Post by tubeprune on Feb 1, 2012 7:17:47 GMT
Sounds like a semi-automatic signal. In LUL terms it would have the local IMR/cabin letters and then a number. This is rather a generalisation. Most LU station starting signals remain at danger, even if they are automatic. They are only cleared when a train occupies the approach track (assuming the section ahead is clear, of course). |
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Feb 1, 2012 8:18:09 GMT
Post by pgb on Feb 1, 2012 8:18:09 GMT
An automatic signal - aspect usually clear - when failing becomes a "signal remaining at danger." That is, it is not returning to its usual aspect. /quote] I find this statement very interesting. I've always been taught (not LU) that any signal has a usual aspect of danger (or caution on distants). To regard a signal as usually clear until you see it at danger seems a bit bizarre to me. |
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Feb 1, 2012 9:07:26 GMT
Post by v52gc on Feb 1, 2012 9:07:26 GMT
I've always been taught (not LU) that any signal has a usual aspect of danger (or caution on distants). To regard a signal as usually clear until you see it at danger seems a bit bizarre to me. A signal will "fail" to danger. It is "fail safe". Some wouldn't call it a failure as the signal is doing what it should be doing, protecting the section ahead. An auto's usual aspect is green because that's how they mostly work, going to red, danger, when the section ahead is occupied. Not to say in any way that they should be assumed to always be clear, green, on approach. Quite the opposite actually in a lot of cases. |
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Feb 1, 2012 15:36:17 GMT
Post by mrfs42 on Feb 1, 2012 15:36:17 GMT
A signal will "fail" to danger. It is "fail safe" Oh no it won't! Just when you think you've got everything sussed you end up with a wrongside failure and the stick is stuck at green.  |
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Feb 1, 2012 15:45:56 GMT
Post by memorex on Feb 1, 2012 15:45:56 GMT
To regard a signal as usually clear until you see it at danger seems a bit bizarre to me. You don't. As a driver you always expect the signal ahead to be at danger - (at least I suppose in a two aspect area). The 'usually green' refers to how the signalling actually works, not to how you would treat the signal if you were a driver. |
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Feb 1, 2012 20:17:41 GMT
Post by Deleted on Feb 1, 2012 20:17:41 GMT
there has been another TR remaining up and it was only noticed upon testing on a signal failure and the t/o finding the TR up when it should of been down thus another check of all vane type relays be it SEV (single element vane) or DEV (double element vane) it was proved to be the collapse of the jewel bearing (the bearing holding the spindle where the vane is connected too) mr railtech was the TR in question you are on about located around stamford brook - ravenscourt park ? as i seem to recall one sticking up when i first started on lu
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metman
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Feb 1, 2012 21:28:01 GMT
Post by metman on Feb 1, 2012 21:28:01 GMT
Sounds like a semi-automatic signal. In LUL terms it would have the local IMR/cabin letters and then a number. This is rather a generalisation. Most LU station starting signals remain at danger, even if they are automatic. They are only cleared when a train occupies the approach track (assuming the section ahead is clear, of course). I noticed this on the Uxbridge branch and often wondered the reason. |
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Feb 1, 2012 22:03:14 GMT
Post by v52gc on Feb 1, 2012 22:03:14 GMT
A signal will "fail" to danger. It is "fail safe" Oh no it won't! Just when you think you've got everything sussed you end up with a wrongside failure and the stick is stuck at green. True, true. For got to add "meant to". ;D But they do "try" to fail safe...  A horrible Signal that didn't fail safe was Charing Cross! |
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Feb 2, 2012 7:06:39 GMT
Post by tubeprune on Feb 2, 2012 7:06:39 GMT
This is rather a generalisation. Most LU station starting signals remain at danger, even if they are automatic. They are only cleared when a train occupies the approach track (assuming the section ahead is clear, of course). I noticed this on the Uxbridge branch and often wondered the reason. It was done to overcome the perceived risk in compromised overlaps - basically to force non-stopping trains to reduce speed. |
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Feb 2, 2012 10:05:16 GMT
Post by citysig on Feb 2, 2012 10:05:16 GMT
As a controller you cannot possibly 'know' what the points are doing just as the remote signal operator cannot 'know' though you may both surmise that they have. You cannot trust anyone 'on the ground' to determine whether or not the points have failed either except the lineman on site dealing with the problem. ...Or the supervisor who has just removed a tin can from the points - and now they work fine... But, of course, you highlight exactly what I meant about us not being able to record the facts as we see them (even if we are 99% certain that the reason something has failed is because of x,y,z). This fact was even more emphasised when PPP came about - when the blame culture really kicked off. It is why, that even to this day, if a tin can is removed from the points, and the points work fine, a fault still has to be raised, a Technical Officer must still attend just to tell us that nothing else is wrong with the points - sometimes causing a (further) delay to the service whilst they do so. |
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Feb 2, 2012 15:40:32 GMT
Post by Deleted on Feb 2, 2012 15:40:32 GMT
Yep same with SPAD's we still have to make sure the trainstop has not been damaged or with a track fire we make sure nothing has been damaged. We have checked all vane relays DEV and SEV relays have been suffering from this Jewel bearing issue where has 3-Position relays suffer from bouncing. Now a new problem has come about where some relays do not shunt correctly when a 1 OHM short is applied to the rails. We have found this to be a problem with the diode in the relay. The relays coming out the SOS have been shocking with a relay only lasting for the last train and failed for the second.
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Feb 4, 2012 12:46:19 GMT
Post by programmes1 on Feb 4, 2012 12:46:19 GMT
Thanks for the reply's
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Feb 5, 2012 20:37:19 GMT
Post by citysig on Feb 5, 2012 20:37:19 GMT
I am amazed that a station supervisor today would get down on the track to remove a tin can from the points. Certainly supervisors in bygone years had no qualms about such things but those I encountered towards the end of my career were often afraid to enter tunnels in traffic hours, didn't know how to clip and scotch points or were unaware of the dangers of halon extinguishing systems. Perhaps station supervisor training has improved in the last few years! Can't comment on the training, but we do still have a very decent band of men and women out there - at least as far as the Met and H&C are concerned, I cannot comment on other lines, but hopefully they have their fair share. |
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