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| Shunt signal failed 21/04/2014 at 06:10 #59186 | |
Josie
310 posts |
In the attached .ssg, signal 689 (UM shunt at Totnes) has failed and is unlit; drivers reaching it will stop and phone in, and the 'train waiting at unlit signal' message appears in the message box. But on the panel it appears to operate normally, showing as red if no route is set, and white if a route is set from it, or a through route from main signal 1 in rear. The only indication that something's wrong is that signal 1 won't clear in the latter case. Can shunt signals be displayed as unlit? Now I think about it I don't think I've ever seen it happen.
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| Shunt signal failed 21/04/2014 at 08:03 #59187 | |
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Late Turn
696 posts |
Assuming that the train encountered the unlit shunt signal whilst running between two main signals, I think the driver did well to be able to stop at it  .More seriously, I think I've read that shunt signals often aren't proved alight, or possibly just that the upper white lamp isn't proved. Perhaps one of the S&T chaps could confirm whether that's the case or whether I'm talking nonsense, but it'd certainly explain this one. Log in to reply |
| Shunt signal failed 21/04/2014 at 11:37 #59200 | |
jc92
3629 posts |
" said:correct (from a Simsig perspective) GPL's do not have proving and will show as cleared regardless of whether there is a lamp out. (there is no lamp out symbol for a shunt signal, at least in Simsig terms, not sure about IRL) "We don't stop camborne wednesdays" Log in to reply |
| Shunt signal failed 21/04/2014 at 12:20 #59201 | |
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Stephen Fulcher
2025 posts 
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Generally, most shunt signals are not proved alight. However, limits of shunt usually are, as are preset shunts (where the shunt is required off as part of a main route). As far as I am aware, SimSig treats them all the same however. What you have actually uncovered here Josie, is a signal that is out on the ground and showing lit on the panel. As mad as this sounds this is quite normal. The panel indications tend to be driven exclusively by the position of the aspect control relay (in this case the GR). If it is up the panel will show off, if it is down the panel will show on. This arrangment has caught out quite a few people, including some who it shouldn't really catch. Log in to reply |
| Shunt signal failed 21/04/2014 at 12:30 #59202 | |
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Firefly
521 posts |
Shunt signals only get proved to be alight if theres a significant risk in the event of an overrun. For this reason the red lamps of Limit of Shunt signals are always proved to be alight because a train passing an unlit limit of shunt would end up continuing in the wrong direction potentially towards oncoming traffic. The only other time we lamp prove shunt signals is the Off lamp of a preset shunt signal (such as the situation you have a Totnes). You have to prove the shunt has come Off before you allow the main signal to clear up to it. This off proving should be indicated on the signallers display so in your case the shunt signal shouldn't show white according to modern standards. That said Exeter is wired to the Western Region E10k standard and the Off lamp is not proved in E10k so SimSig is almost correct. Where SimSig has it wrong is that 1 signal would most likely clear in the event of 689 off lamp failure in the real world. Sorry I couldn't give a straight answer. FF (Edit: Looks like Steve beat me to it) Last edited: 21/04/2014 at 12:31 by Firefly Log in to reply |
| Shunt signal failed 21/04/2014 at 12:34 #59205 | |
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Stephen Fulcher
2025 posts
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I remember the looks of astonishment around the classroom during the preset shunt part of the RRI course - the signal has to be proved "not ON".
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