roythebus
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Post by roythebus on Jan 13, 2017 11:51:14 GMT
There's a question on the Fb district line group regarding warning signals. I seem to remember something about them, but can't remember what they were used for. I know Calling-on signals, especially WF37 approaching Parsons Green, but not Warning signals! My memory is fading...
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Deleted
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Post by Deleted on Jan 13, 2017 12:09:46 GMT
You could have one or more warning signals in the rear of a calling-on signal.
Take, for example, the approach to White City on the eastbound Central.
Beneath outer home signal CG21 was warning signal CG16, complete with miniature junction indicator.
Beneath inner home signal CG19 you had calling-on signal CG14, reading to number 3 platform road (the middle road).
Beneath inner home signal CG20 you had calling-on signal CG15 reading to number 4 platform road (eastbound main).
So a warning signal does what it says on the tin, it's a warning. It's all about controlling the speed of trains about to be cleared on top of another train.
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Post by Deleted on Jan 13, 2017 17:56:00 GMT
You could have one or more warning signals in the rear of a calling-on signal. Take, for example, the approach to White City on the eastbound Central. Beneath outer home signal CG21 was warning signal CG16, complete with miniature junction indicator. Beneath inner home signal CG19 you had calling-on signal CG14, reading to number 3 platform road (the middle road). Beneath inner home signal CG20 you had calling-on signal CG15 reading to number 4 platform road (eastbound main). So a warning signal does what it says on the tin, it's a warning. It's all about controlling the speed of trains about to be cleared on top of another train. Would these work with other equipment? For example, using a train stop to control the speed of a train like done on the met. |
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Deleted
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Post by Deleted on Jan 13, 2017 18:20:33 GMT
You could have one or more warning signals in the rear of a calling-on signal. Take, for example, the approach to White City on the eastbound Central. Beneath outer home signal CG21 was warning signal CG16, complete with miniature junction indicator. Beneath inner home signal CG19 you had calling-on signal CG14, reading to number 3 platform road (the middle road). Beneath inner home signal CG20 you had calling-on signal CG15 reading to number 4 platform road (eastbound main). So a warning signal does what it says on the tin, it's a warning. It's all about controlling the speed of trains about to be cleared on top of another train. Would these work with other equipment? For example, using a train stop to control the speed of a train like done on the met. This was the state of play when the signalling was commissioned in 1948, I honestly couldn't tell you about any subsequent modifications or upgrades to the permissive signalling at White City. Certainly, at commissioning, though, there were only the Δ track circuits. Obviously the warning and calling-on signals would have had associated train stops (the same train stops as the home signals) but otherwise the signalling diagram shows no blind, speed control train stops, nor any mid-platform signals/train stops or anything. However, I do know that a slightly more sophisticated arrangement was used at Loughton, perhaps this eventually made its way to White City? Speed control signalling was also very well developed on the Central line, most notably at Liverpool Street, but also for enforcing certain TSRs in the 50s. Whether any of that ever made its way to White City, I don't know. |
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Post by Deleted on Jan 13, 2017 18:26:08 GMT
Would these work with other equipment? For example, using a train stop to control the speed of a train like done on the met. This was the state of play when the signalling was commissioned in 1948, I honestly couldn't tell you about any subsequent modifications or upgrades to the permissive signalling at White City. Certainly, at commissioning, though, there were only the Δ track circuits. Obviously the warning and calling-on signals would have had associated train stops (the same train stops as the home signals) but otherwise the signalling diagram shows no blind, speed control train stops, nor any mid-platform signals/train stops or anything. However, I do know that a slightly more sophisticated arrangement was used at Loughton, perhaps this eventually made its way to White City? Speed control signalling was also very well developed on the Central line, most notably at Liverpool Street, but also for enforcing certain TSRs in the 50s. Whether any of that ever made its way to White City, I don't know. So these warning signals are, put simply, just another signal before/after another signal with the idea being that they are used as a warning about what could be ahead. |
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roythebus
Pleased to say the restoration of BEA coach MLL738 is as complete as it can be, now restoring MLL721
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Post by roythebus on Jan 13, 2017 18:46:28 GMT
Overlaps, that's what it must have been. On WF37 there was a good 3 or 4 train lengths between the signal and the paltform, and no further signals. About 12 cars away were the points which are the exit from the sidings, then the points from e/b and w/b sidings, then the length of the platform. I'm not familiar with White City but presumably the home signals there were much closer to the platforms, hence the need for warning signals.
At WF37 the train ahead to be brought to a stand before it would clear, and as on BR, the calling-on signal would clear indicating to the motorman that the train was going into an occupied section and to stop short of any obstruction. I don't see that you'd need a warning signal followed by a calling-on signal.
I'm also familiar with the speed control signalling fitted on the DR in the 60's and 70's where you'd have a number of home signals with the same number for instance A123a, A123b, A123c etc which would clear in sequence as the train ahead moved out of the platform. It was possible at places with short distances between stations to have the back of one train leaving the platform and the front of the following train entering the paltform, still with a green light in front of it and a red light protecting the one in front. It was a form of speed controlled signalling, something different to the calling-on signals.
I don't have my LT rule book any more, but may still have the earler 1956 edition update of the 1933 book which should give some information on warning signals.
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Deleted
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Post by Deleted on Jan 13, 2017 18:59:29 GMT
This was the state of play when the signalling was commissioned in 1948, I honestly couldn't tell you about any subsequent modifications or upgrades to the permissive signalling at White City. Certainly, at commissioning, though, there were only the Δ track circuits. Obviously the warning and calling-on signals would have had associated train stops (the same train stops as the home signals) but otherwise the signalling diagram shows no blind, speed control train stops, nor any mid-platform signals/train stops or anything. However, I do know that a slightly more sophisticated arrangement was used at Loughton, perhaps this eventually made its way to White City? Speed control signalling was also very well developed on the Central line, most notably at Liverpool Street, but also for enforcing certain TSRs in the 50s. Whether any of that ever made its way to White City, I don't know. So these warning signals are, put simply, just another signal before/after another signal with the idea being that they are used as a warning about what could be ahead. Warning signals are not compulsory, you may just have the calling-on signal. The calling-on signal will be provided beneath the inner-home signal. It will not be possible to lower the inner-home signal if a platform track is occupied. In order to signal a train on top of another train, the train must be allowed to draw well up to the inner-home signal. When a short track circuit on the approach side of the signal has been occupied, the signalman may lower the calling-on signal and allow the train to enter the platform and approach the train already there, so as to couple up. One or more warning signals may be installed in the rear of the calling-on signal and they will be mounted beneath the home signals. If it is desired to signal a train into a platform which is already occupied, one must not lower the main signals, but use the warning signals. So, for example, let's say we have a train standing in platform 3 at White City awaiting another train approaching White City on the eastbound, to couple up. The train will pass CGX379 with a straight green. We will lower signal CG22, which will clear with a straight green. RCG21, mounted beneath, will be yellow of course. The train will approach CG21, with warning signal CG16 mounted beneath it. We will reverse number 11 points (when this is to be done, I couldn't tell you), and when Δ16 track circuit has been occupied, it will be possible to lower warning signal CG16, which will clear with three white lights to the left. We will not lower CG21. CG16 will authorise the train past CG21 at danger. This will permit a train up to CG19, with calling-on signal CG14 mounted beneath it. When Δ14 track circuit has been occupied, it will be possible to lower calling-on signal CG14, permitting the train to enter a block which is already occupied by another train. The train must proceed with caution and be prepared to stop short of any obstruction. It must draw cautiously up to the train in the platform. Some pictures of a fictionalised layout and another explanation can be found here. Overlaps, that's what it must have been. On WF37 there was a good 3 or 4 train lengths between the signal and the paltform, and no further signals. About 12 cars away were the points which are the exit from the sidings, then the points from e/b and w/b sidings, then the length of the platform. I'm not familiar with White City but presumably the home signals there were much closer to the platforms, hence the need for warning signals. Calling-on signal CG14 was mounted on the platform itself, you can see a great picture of it here. CG16 was about 436 feet in the rear of it, I think, the diagram is quite cluttered! |
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Post by Deleted on Jan 13, 2017 20:26:29 GMT
Warning signals were only necessary if there was more than one home signal. They allowed the outer home (and intermediate home(s) where present) to be passed at danger - at a slow speed - to enable the train to reach the calling-on signal at the inner home. If you didn't have these Warning signals then the only way for a train to reach the calling on signal would be to "apply the rule" at the outer and intermediate homes (which of course cannot be cleared because the platform is occupied). This would have been time-consuming and required any points in the route to be secured, which is not a very expedient way of carry out routine coupling operations!
At locations with just one home signal, there was no reason to have warning signal(s), and you'd just have a calling-on signal mounted beneath the home signal.
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roythebus
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Post by roythebus on Jan 14, 2017 22:59:50 GMT
That sounds familiar. BR has a slightly different process with home signals. If you have to couple to a train already in the platform, the following train is bough to or nearly to a stand at the outer home, which is then slowly cleared (easy with semaphores but not with colour-lights, try changing aspect slowly), then the train can proceed to the inner home which will have the calling-on signal which will then clear to allow the following train into the platform. IIRC the warning signal is peculiar to LT.
I don't remember seeing them on the DR or the MR which are the lines I worked on.
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Post by Deleted on Jan 14, 2017 23:48:11 GMT
That sounds familiar. BR has a slightly different process with home signals. If you have to couple to a train already in the platform, the following train is bough to or nearly to a stand at the outer home, which is then slowly cleared (easy with semaphores but not with colour-lights, try changing aspect slowly), then the train can proceed to the inner home which will have the calling-on signal which will then clear to allow the following train into the platform. IIRC the warning signal is peculiar to LT. I don't remember seeing them on the DR or the MR which are the lines I worked on. There is certainly such a thing as a warning signal on National Rail. However, it's function is rather different. A semaphore warning signal is used to authorise a train to enter a block section where the block section is clear, but the overlap is occupied, that is to say the line is not clear up to the clearing point, but the line is clear up to the outer home signal. It is, I believe, subject to certain conditions, possible in the generic case to authorise a train to pass the section signal at danger and to enter the block ahead, with the overlap occupied, provided the driver has been warned by the signalman and provided there are no passengers being carried. Where this is frequently required, a warning signal is provided so that the signalman doesn't need to give verbal authority, which would have been very tedious in the early days before widespread use of telephones and long before CSR, GSM-R, or NRN. With colour light signalling this has been replaced, of course, with the warner route/reduced overlap. The signalman may select the route on an NX panel by using a different exit(?) button, or, in an IECC-type installation, by routing to a yellow exit triangle, rather than the exit signal. This essentially causes the signal to be approach controlled, such that the signal will clear subject to the train's speed on approach being proved sufficiently low by means of timing circuits. At some locations, warner routes will be automatically selected according to circumstances. |
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rincew1nd
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Post by rincew1nd on Jan 15, 2017 8:09:10 GMT
Regulation five (warning acceptance) has led to problems in the past. Clicky. |
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roythebus
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Post by roythebus on Jan 15, 2017 12:27:45 GMT
That sounds familiar. BR has a slightly different process with home signals. If you have to couple to a train already in the platform, the following train is bough to or nearly to a stand at the outer home, which is then slowly cleared (easy with semaphores but not with colour-lights, try changing aspect slowly), then the train can proceed to the inner home which will have the calling-on signal which will then clear to allow the following train into the platform. IIRC the warning signal is peculiar to LT. I don't remember seeing them on the DR or the MR which are the lines I worked on. There is certainly such a thing as a warning signal on National Rail. However, it's function is rather different. A semaphore warning signal is used to authorise a train to enter a block section where the block section is clear, but the overlap is occupied, that is to say the line is not clear up to the clearing point, but the line is clear up to the outer home signal. It is, I believe, subject to certain conditions, possible in the generic case to authorise a train to pass the section signal at danger and to enter the block ahead, with the overlap occupied, provided the driver has been warned by the signalman and provided there are no passengers being carried. Where this is frequently required, a warning signal is provided so that the signalman doesn't need to give verbal authority, which would have been very tedious in the early days before widespread use of telephones and long before CSR, GSM-R, or NRN. With colour light signalling this has been replaced, of course, with the warner route/reduced overlap. The signalman may select the route on an NX panel by using a different exit(?) button, or, in an IECC-type installation, by routing to a yellow exit triangle, rather than the exit signal. This essentially causes the signal to be approach controlled, such that the signal will clear subject to the train's speed on approach being proved sufficiently low by means of timing circuits. At some locations, warner routes will be automatically selected according to circumstances. Yes, the warning on BR was the signal being cleared slowly which I referred to earlier. It wasn't a separate signal. In my years on BR it was used infrequently on passenger lines. On permissive goods lines it was used quite a bit. |
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Post by Deleted on Jan 15, 2017 12:33:35 GMT
There is certainly such a thing as a warning signal on National Rail. However, it's function is rather different. A semaphore warning signal is used to authorise a train to enter a block section where the block section is clear, but the overlap is occupied, that is to say the line is not clear up to the clearing point, but the line is clear up to the outer home signal. It is, I believe, subject to certain conditions, possible in the generic case to authorise a train to pass the section signal at danger and to enter the block ahead, with the overlap occupied, provided the driver has been warned by the signalman and provided there are no passengers being carried. Where this is frequently required, a warning signal is provided so that the signalman doesn't need to give verbal authority, which would have been very tedious in the early days before widespread use of telephones and long before CSR, GSM-R, or NRN. With colour light signalling this has been replaced, of course, with the warner route/reduced overlap. The signalman may select the route on an NX panel by using a different exit(?) button, or, in an IECC-type installation, by routing to a yellow exit triangle, rather than the exit signal. This essentially causes the signal to be approach controlled, such that the signal will clear subject to the train's speed on approach being proved sufficiently low by means of timing circuits. At some locations, warner routes will be automatically selected according to circumstances. Yes, the warning on BR was the signal being cleared slowly which I referred to earlier. It wasn't a separate signal. In my years on BR it was used infrequently on passenger lines. On permissive goods lines it was used quite a bit. Not necessarily, a number of styles of separate warning signals were provided over the years, detailed on this and subsequent pages. There's also quite a nice description of warning signal B61 on this Flickr page. |
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roythebus
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Post by roythebus on Jan 15, 2017 20:09:32 GMT
Seems like the warning signals on BR fell out of general use by 1970, apart from the one at Barry! I don't recall ever seeing one, I worked at Rugby and Kings Cross as a secondman, then Addiscombe and Waterloo as driver. I still can't recall seeing one on my travels!
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Post by Deleted on Jan 15, 2017 22:08:56 GMT
Seems like the warning signals on BR fell out of general use by 1970, apart from the one at Barry! I don't recall ever seeing one, I worked at Rugby and Kings Cross as a secondman, then Addiscombe and Waterloo as driver. I still can't recall seeing one on my travels! From a brief (and I stress the word) glance at the modern edition of the Signalling Rule Book I can find no mention of them either, they're certainly on their way out if there are any left. |
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Post by revupminster on Jan 16, 2017 7:25:58 GMT
My rules and regulation notes from May 1974:
A warning signal is only provided when where a calling on signal is not a safe braking distance from platform. Train detected by delta track before signal and if moving at slow walking space signalman can clear signal, visual indication given in signal cabin.
1/ Proceed at caution
2/ Allow train to enter section ahead as far as next stop signal.
3/ Be prepared to stop at that signal as section ahead occupied.
Calling on Signal
Train has to stop before signalman can clear signal. Visual indication given in signal cabin that train is stopped. Delta track (11' 83/4") detects train.
1/ Proceed at caution once cleared
2/ Section being entered is occupied
3/ Be prepared to stop 10' short of train.
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Tom
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Post by Tom on Jan 16, 2017 7:49:33 GMT
Seems like the warning signals on BR fell out of general use by 1970, apart from the one at Barry! I don't recall ever seeing one, I worked at Rugby and Kings Cross as a secondman, then Addiscombe and Waterloo as driver. I still can't recall seeing one on my travels! From a brief (and I stress the word) glance at the modern edition of the Signalling Rule Book I can find no mention of them either, they're certainly on their way out if there are any left. They were superseded by a 'Warning' class of route - basically a delayed yellow aspect. Remember that BR/NR had much stricter rules about signal spacing than LU, and only arbitary overlap distances. |
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roythebus
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Post by roythebus on Jan 16, 2017 15:32:47 GMT
On LT braking distances were more predictable due to fixed train lengths (LOL, pre-Westcode and anti-slip brakes); on BR train lengths and braking distances varied considerably, anything from a 80 ton unfitted goods train at 25 mph to an inter-city 125 or a suburban EMU! But yes. on BR the signal being cleared when the train was at or nearly at a stand was regarded as the warning signal where no separate aspect was provided. As I said earlier, all to do with overlaps and braking distances. This also accounts for the banner type distant signals that used to be provided on the Met main line.
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