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| Does it need to be a controlled signal? 10/02/2014 at 00:03 #55333 | |
John
884 posts |
As an example, VS380 is a controlled signal with auto facility. There is only one route available from this signal and setting it does not conflict with another route, so why does is it need to be controlled? I seem to recall reading somewhere that there must be a controlled signal after x amount of automatics, but in this case there is a controlled signal directly behind VS380. 
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| Does it need to be a controlled signal? 10/02/2014 at 01:42 #55336 | |
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Stephen Fulcher
2026 posts |
No real reason looking at the display there. Possibly used to be some points or something there, or perhaps provision in case points were later installed? Log in to reply |
| Does it need to be a controlled signal? 10/02/2014 at 06:12 #55339 | |
GeoffM
6284 posts |
Ahem :blush: . Panel photos clearly show an auto there. Logged for fixing.
SimSig Boss Log in to reply |
| Does it need to be a controlled signal? 10/02/2014 at 06:41 #55342 | |
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clive
2738 posts |
I've seen Geoff's post, so this is generic. Sometimes there's something not very obvious. For example, there may be a route to a limit of shunt signal a couple of blocks ahead, such that it fouls the overlap of the next signal. The signal then needs to be controlled to prevent trains being signalled both ways into that overlap. But sometimes it's a mystery. There's one controlled signal on the Up Fast just north of St.Neots (P324, I think). There is no obvious reason for it, and none of the signallers have the slightest idea either. Log in to reply |
| Does it need to be a controlled signal? 10/02/2014 at 11:47 #55350 | |
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jimgos2005
129 posts |
I was wondering if the said signal was a controlled signal so that a train can be held there if theres a problem with the points or it the rarest of scenarios a train fails whilst on the points this is just an idea Log in to reply |
| Does it need to be a controlled signal? 10/02/2014 at 12:21 #55352 | |
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Late Turn
696 posts |
" said:I was wondering if the said signal was a controlled signal so that a train can be held there if theres a problem with the points or it the rarest of scenarios a train fails whilst on the points No. The next signal in advance - which is a controlled signal - protects the pointwork at Blackfriars Jn perfectly adequately. Log in to reply |
| Does it need to be a controlled signal? 10/02/2014 at 15:41 #55364 | |
pedroathome
889 posts 
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This is something which I think I've seen on most sims. Without knowing the initial requirements of the installation (It's possible that there may have been a plan for a siding, loop, or something else there in the very early stages after signal placement was first thought of.
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| Does it need to be a controlled signal? 10/02/2014 at 16:21 #55367 | |
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GeoffM
6284 posts |
A fair few have sprung up on the WCML with nobody - including signallers - really knowing why they're controlled signals.
SimSig Boss Log in to reply |
| Does it need to be a controlled signal? 10/02/2014 at 21:05 #55371 | |
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Jsun
212 posts |
I noticed the oddity, but I wrote it off as a signal from a different era being converted to an automatic. But it appears that was not the case.
Last edited: 10/02/2014 at 21:05 by Jsun Log in to reply |
| Does it need to be a controlled signal? 10/02/2014 at 23:46 #55379 | |
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Stephen Fulcher
2026 posts |
Controlled signals at the edge of interlocking areas are fairly common on many Western Region panels, and certainly in older installations they often did not have route lights or exit buttons on the first auto thereafter. Exeter has quite a few of these, for example on the down just west of Newton Abbot. Looking again at the picture in the first post, there is a clue I missed last night suggesting an auto - namely the lack of a separate overlap track. For the sim, just leave it set on auto and it will work just the same anyway. Log in to reply |
| Does it need to be a controlled signal? 11/02/2014 at 00:48 #55386 | |
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GeoffM
6284 posts |
" said:Looking again at the picture in the first post, there is a clue I missed last night suggesting an auto - namely the lack of a separate overlap track.Means nothing for the Southern region! There are six other controlled signals with no overlap in that picture alone. I've also noticed a couple spring up outside the Southern - probably thinking WCML again here. SimSig Boss Log in to reply |
| Does it need to be a controlled signal? 11/02/2014 at 00:55 #55387 | |
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Stephen Fulcher
2026 posts |
And there was me thinking it was only the Western who "ignored" the accepted norm! I must confess to only really looking at the signal with the arrow pointing at it. Log in to reply |
| Does it need to be a controlled signal? 11/02/2014 at 08:41 #55400 | |
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mfcooper
707 posts |
" said:Looking again at the picture in the first post, there is a clue I missed last night suggesting an auto - namely the lack of a separate overlap track.A separate overlap track circuit!? What Luxury! There are so many signals on the central side without this. It makes replacing a junction signal interesting when you can't be sure if the driver is approaching what will become the last green or if they are beyond it within the overlap. Last edited: 11/02/2014 at 08:41 by mfcooper Log in to reply |
| Does it need to be a controlled signal? 11/02/2014 at 14:58 #55414 | |
jc92
3629 posts
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" said:on peterbro sim, there are four controlled signals with automatic working available just south of stoke summit which have no apparent purpose. I think theres also a few north of York like that aswell "We don't stop camborne wednesdays" Log in to reply |
| Does it need to be a controlled signal? 11/02/2014 at 16:30 #55425 | |
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Sacro
1171 posts |
" said:Bytham used to be a junction, and I've heard there was talk of having crossovers when the panel was comissioned but they never got put in. Log in to reply |
| Does it need to be a controlled signal? 11/02/2014 at 22:21 #55442 | |
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clive
2738 posts |
" said:" said:Also, didn't there used to be a level crossing there? (Not necessarily a public road.)Bytham used to be a junction, and I've heard there was talk of having crossovers when the panel was comissioned but they never got put in. Log in to reply |
| Does it need to be a controlled signal? 12/02/2014 at 05:59 #55447 | |
Soton_Speed
282 posts |
Do various railway structures such as bridges and tunnels need an associated controlled signal in case of incident (bridge strike/ tunnel collapse etc)? Or are emergency replacements used?
In Zone 6, no one can hear you scream... Log in to reply |
| Does it need to be a controlled signal? 12/02/2014 at 10:05 #55457 | |
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kbarber
1712 posts |
" said:Do various railway structures such as bridges and tunnels need an associated controlled signal in case of incident (bridge strike/ tunnel collapse etc)? Or are emergency replacements used? Would usually be an emergency replacement, I think. Log in to reply |
| Does it need to be a controlled signal? 12/02/2014 at 17:54 #55470 | |
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Hooverman
306 posts |
All of our tunnels, viaducts and AHBs are protected by emergency replacements where they don't fall within any junction interlockings.
Last edited: 12/02/2014 at 18:40 by Hooverman Log in to reply |
| Does it need to be a controlled signal? 12/02/2014 at 18:44 #55475 | |
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Lardybiker
771 posts |
This may not be true of all locations but I have certainly seen situations where a controlled signal was used at a junction on a line where there are auto signals in use either side. However, sometime after it was installed, the junction was removed and the track made just plain line and there is no indication now a diverging route ever existed but the signalling remains the same even though the signal could now be made an automatic as there is now only one route. I suspect this was because a manually-controlled signal with its auto button activated follows the same aspect sequence as an automatic signal would so why go to the time and effort and expense of changing something that is known to be work correctly to replace a signal that in essence will end up doing pretty much the same thing as the current signal already is and opening up the possibility of introducing problems as a result (phrase "If it 'ain't broke, don't fix it" springs to mind). Yes, it may look a little out of place but to me, it doesn't make much commercial sense to spend the money to change it. In addition, if for any reason the diverging route is ever re-instated, the signalling is already there to cope. Log in to reply |
| Does it need to be a controlled signal? 12/02/2014 at 18:46 #55476 | |
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Stephen Fulcher
2026 posts |
Age of the installation may have a bearing on this issue as well. Older installations tended to have emergency replacements which were not "relied upon". In this regard although they were set on the panel, no positive indication was returned back to the panel that the signal was lit and at danger. There were sometimes indications for these signals which showed that the panel function calling the signal back to red had been set, but not the indications on the ground. This meant that in order to ensure a signal was at danger when you wanted it to be, you had to place a controlled signal. Newer installations tend to have replacement switches which are guaranteed, and have the appropriate indications on the panel which reflect what is going on on the ground, thereby removing the need to place so many controlled signals. Log in to reply |
| Does it need to be a controlled signal? 04/03/2014 at 03:55 #56504 | |
DaveBarraza
88 posts |
" said:...Newer installations tend to have replacement switches which are guaranteed, and have the appropriate indications on the panel which reflect what is going on on the ground, thereby removing the need to place so many controlled signals.This is a discussion I've had many times: Can cancelling a signal be considered a vital function? As soon as the control for the signals is no longer "closed loop" how is it possible to guarantee that the appropriate output from the remote system will change states when the signaler cancels the signal? Is there anything done beyond returning the indication that the field has reacted? Thanks, Dave Log in to reply |
| Does it need to be a controlled signal? 04/03/2014 at 05:01 #56506 | |
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GeoffM
6284 posts |
Hmm, now you're asking difficult questions! Here is my understanding, flawed though it may be. In the EU there are five levels of safety integrity, from zero (non-safety) to four (interlocking - safety-critical). In practice, 1 and 2 are similar, and 3 and 4 are similar. We could simplify this to: non-safety, safety-related, and safety-critical. Generally a control system (panel/VDU) would be safety-related, while an interlocking would be safety-critical. So, on that basis, could controlling a signal to danger be relied upon to actually return that signal to danger? Theoretically no, as the panel is only safety-related. But in practice, it's good enough for the safety people for its desired purpose so as far as the rules & regs are concerned, it can be relied upon. Put another way, urine may still be extracted but disregarded later! Incidentally, an odd quirk of panels is that proof of track clear can be provided by at least two burnt out lamps. :S Probably mitigated by maintenance requirements if a TC only has two lamps to prove clearance. 
SimSig Boss Log in to reply |
| Does it need to be a controlled signal? 04/03/2014 at 11:26 #56511 | |
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kbarber
1712 posts |
" said:" said:...Newer installations tend to have replacement switches which are guaranteed, and have the appropriate indications on the panel which reflect what is going on on the ground, thereby removing the need to place so many controlled signals.This is a discussion I've had many times: Can cancelling a signal be considered a vital function? As soon as the control for the signals is no longer "closed loop" how is it possible to guarantee that the appropriate output from the remote system will change states when the signaler cancels the signal? Might there be a conceptual difference between 'cancelling' a signal (in modern practice cancelling a route) and controlling a signal to danger? Cancelling seems to me to be about an operational decision that doesn't have safety implications (changing the order of trains, changing the route a train is to take, terminating a train). Controlling a signal to danger, on the other hand, is what I'd want to do to protect an obstruction or otherwise secure safety. In that case I'd want to be able to assure myself that the signal had answered my action correctly - that is the 'guaranteed' function Stephen is referring to. Dave, I'm not sure whether you're implying that an indication of the actual state of the signal is 'closed loop' or not? Given that we're talking about emergency replacement, I'd say the signalman is necessarily part of the loop. If, on the other hand, the indication is not driven by the actual state of the signal (and carried back by safety circuits to boot) I wouldn't want to rely on it if lives were at stake. In that case I can't see that there's any loop at all! Log in to reply |
| Does it need to be a controlled signal? 04/03/2014 at 15:58 #56525 | |
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Stephen Fulcher
2026 posts |
On older E10k panels, there were two types of emergency replacement, one that can be relied upon and one that cannot (at least in theory). http://photos.signallingnotices.org.uk/photo.php?pc=81&p=IMG_8017.JPG shows an example that can be guaranteed. What happens here is that the signalman operating the replacement function will cause the white light below the signal going out. This function being operated will eventually be cut into the aspect control relays of the signal concerned, and replace the signal to danger. With the function operated, signal at red AND lit, an indication will be sent back to the panel which will put a red light in the signal itself on the panel, which confirms that it is indeed at red and lit on the ground, as shown in this picture http://photos.signallingnotices.org.uk/photo.php?pc=81&p=IMG_8018.JPG http://photos.signallingnotices.org.uk/photo.php?pc=81&p=IMG_8021.JPG shows an example that CANNOT be guaranteed. Here, the white light works as above, but when operated the white light turns red, but this does not have any information coming back from the ground, so it indicates merely that the replacement facility in the relay room has responded to the switch, not that the signal has responded to it. This is shown here http://photos.signallingnotices.org.uk/photo.php?pc=81&p=IMG_8020.JPG Pictures courtesy of Danny Scroggins. Log in to reply The following users said thank you: UKTrainMan, DaveBarraza |
