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| Signal failures and aspects 23/03/2014 at 05:08 #57601 | |
Hawk777
386 posts |
Hello! I was wondering if someone could enlighten me about signal failures. Sometimes, when a signal failure is reported, the signal goes black and nothing I do will make any difference until it’s repaired. Other times, only certain aspects fail—perhaps green is unavailable, but if I hit an emergency replacement switch further down the line (for example), I can force the signal down to yellow, at which point it comes back to life, allowing me to get trains past the signal without stopping by judicious use of the emergency replacement switch to let them pass the signal at yellow, then clear the next signal once they’re past. So my question is, what are the underlying factors being modelled here? Is it as simple as, sometimes one filament dies and sometimes the whole signal head dies (e.g. a cut cable), and the choice of which fails in SimSig is random? Or is there some greater safety reason why certain failures take the whole signal out of service, which I’m not realizing—something like, if the last filament in the red lamp fails, the signal must never display any aspects until repaired, but if the green filament fails, the other aspects can still be used? Log in to reply |
| Signal failures and aspects 23/03/2014 at 09:28 #57611 | |
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AndyG
1834 posts |
No doubt Stephen Fulcher will be able to give a definitive answer at some point, but I think it can be related to the lamp proving and related interlocking eg does the aspect control 'step-up' thought the failed aspect, or step around it. Probably different types of interlocking (eg relay/SSI) work differently too. I can only help one person a day. Today's not your day. Tomorrow doesn't look too good either. Log in to reply |
| Signal failures and aspects 23/03/2014 at 09:47 #57614 | |
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Firefly
521 posts |
Signal failures can generally be split into 3 categories. 1) Failure of a single aspect 2) Failure of all aspects 3) Failure of Controls (Signal will not clear) The possible scenarios are:- 1) A single aspect could fail as a result of a blown lamp, a faulty relay contact or a broken wire. The signals controls are still working perfectly so you can get around the problem be simply preventing the signal displaying the faulty aspect. 2) For all of the aspects to fail you could be looking at a blown fuse (on RRI all aspects are fed by the same fuse), a wire broken on part of the common circuitry, a severed cable, a problem with the lamp proving circuitry or perhaps a complete loss of power to a particular location cabinet. In this case it doesn't matter what aspect you clear the signal to it will always be failed. On many older RRI interlockings they have a function called "Lamp or Controls" If fitted it allows the signal in rear to step up to a single yellow despite the fact that the faulty signal is not displaying an aspect. This can only occur when the faulty signal should be displaying a proceed aspect (controls are off), so the signal in rear requires the next signal to have lamp alight OR controls off. 3) By far the most common failure would be that a signal does not clear to a proceed aspect. On RRI this could be due to a faulty relay contact, a broken wire, a light contact on a link, a dodgy signal post replacement switch, faulty TDM or FDM, a dodgy panel button the possibilities are endless. There are a lot of different circuits and relay contacts required to be in the correct position to give a proceed aspect so there are a lot of failure points. On SSI it could be that the TFM (Trackside Functional Module) has either blown it's security fuse, it's output interface or once again the location cabinet has lost it's supply. Total module failures on SSI are usually accompanied by track circuit failures because a lot of signal modules also have track circuits in them . Log in to reply The following users said thank you: John, Hawk777 |
| Signal failures and aspects 24/03/2014 at 15:15 #57672 | |
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mfcooper
707 posts |
" said:On many older RRI interlockings they have a function called "Lamp or Controls" If fitted it allows the signal in rear to step up to a single yellow despite the fact that the faulty signal is not displaying an aspect.Just like most of London Victoria ASC. It still freaks out some of the Control staff when we tell them drivers are getting a single yellow on approach to a black-vice-proceed signal. Don't panic! It's all working as designed. It's just that the designs have changed in the last 30 years! Last edited: 24/03/2014 at 15:16 by mfcooper Log in to reply |
| Signal failures and aspects 03/04/2014 at 11:19 #58302 | |
NCC1701
129 posts |
Playing Coventry, at sim time 1233 I get a signal failure message "in the Tile Hill area". 1M38 is approaching a black signal. I immediately cancel the route from the signal - signal 80 - to get a red aspect: only the green has failed. 1M38 anchors up and there follows the message saying 1M38 is waiting at red signal 80, this also timed at 1233, as you can see in the screen grab one minute later. In less than a minute the aspect shown to the approaching 1M38 has gone green - black - red and yet the driver managed to stop at the signal. I fully understand the desire of the devs not to simulate SPADs but surely in real life this would be impossible to avoid in this time frame. What would be the protocol for a driver - and the signaller - to follow in this situation? Should SimSig's code be modified to either allow this form of SPAD or prevent a signal failure occurring immediately in front of a train? :unsure: (And yes, there is a second SF on the opposite line! Yellow aspect out on that one. That's caused a few ACOAs! :woohoo:) Edit: resuming the sim, 1M38 hasn't called in to complain either at the affected signal or the subsequent one. Post has attachments. Log in to view them. Signalman Exeter West & Llangollen Last edited: 03/04/2014 at 11:26 by NCC1701 Log in to reply |
| Signal failures and aspects 03/04/2014 at 11:52 #58305 | |
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Firefly
521 posts |
I wouldn't pull up on a black signal when there is a train approaching. It could be an indication problem only and the signal could still be showing green on the ground. Let the driver stop and report in. Even when he does report in, if it's a controlled signal it's better to authorise a train past a signal when the route is set because that guarantees your points are set the correct way and it gives you route locking. Log in to reply The following user said thank you: NCC1701 |
| Signal failures and aspects 03/04/2014 at 20:54 #58330 | |
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clive
2738 posts |
" said:It is a policy decision that trains do not SPAD, even if that means unrealistic braking. Right now trains won't accept a wrong route at a signal, even if that means unrealistic braking as well. There's an open bug in the tracking system to fix that, but it's a major job. Log in to reply |
| Signal failures and aspects 03/04/2014 at 21:30 #58332 | |
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Lardybiker
771 posts |
Clive, What about adding a condition to prevent signal from failing if there is a train approaching or put another way, at least far enough away it can't brake properly. Log in to reply |
| Signal failures and aspects 04/04/2014 at 09:18 #58365 | |
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kbarber
1712 posts |
" said:" said:It is a policy decision that trains do not SPAD, even if that means unrealistic braking. However trains will SPAD if a signal is reversed (ACOA) and the movement is protected by approach locking. Perhaps a signal going black could be treated in that way too? (Preferably without the ACOA penalty, for the sake of those that worry about their score.) Log in to reply |
| Signal failures and aspects 04/04/2014 at 11:34 #58373 | |
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Jan
889 posts |
Will they? I seem to remember this feature being discussed a few months or possibly years ago, but at least in the public version trains are still stopping instantaneously if you pull a signal in front of them, even if the route is being held by approach locking.
Two million people attempt to use Birmingham's magnificent rail network every year, with just over a million of them managing to get further than Smethwick. Last edited: 04/04/2014 at 13:52 by Jan Log in to reply |
| Signal failures and aspects 04/04/2014 at 18:09 #58392 | |
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Danny252
1461 posts |
Indeed, can you provide an example of this behaviour in Simsig? As far as I've observed, trains will magically stop at the first signal they come to when receiving an ACOA.
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| Signal failures and aspects 04/04/2014 at 20:10 #58397 | |
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clive
2738 posts |
" said:The calculation is complicated enough that it would have to be "if there's a train that would see any ACoA". But what about track circuit failures that might cause a SPAD? Have those got to be suppressed as well? Unless Geoff disagrees with me, I think it should stay unchanged. Last edited: 04/04/2014 at 20:11 by clive Log in to reply |