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Clearing subsidiary signals.


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G,day all. I must be losing the plot but just to be sure... There was no need to lower subsidiary signals before clearing the main stop signal above was there? ( I am sure I read this maybe in the general appendix but I cannot recall ...). I am thinking of LNER or GWR in the 1930s.

 

Regards

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....when clearing subsiduary signals the main aspect remains at danger....the clearing of the subsiduary authorises the passing of the main aspect at danger....route knowledge and/or assocated letters tell one what to expect and how to proceed. At least latterly C, W and S were those letters....C = calling on, W = under the warning and S = shunt ahead. All movements to be made at caution ready to stop short of any obstruction.

 

Dave

Edited by Torr Giffard LSWR 1951-71
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The interlocking would prevent both arms being "Off" at the same time. The only exception I know of was the NERly, were the Calling On arm was always pulled first, and so both arms could  be off together. This stems from the practice on the Northern Division, of working both arms off the same lever. To clear the Calling On arm, the lever was pulled mid stroke, and to clear the Main arm it was fully reversed. On the Southern Division, where separate levers were always used, for conformity through out the railway, the interlocking was arranged that the Calling On signal released the Main Arm.

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Rather oddly, this North Eastern Railway practice seems to have spread on occasion to other locations on the LNER network although I would stress that it wasn't normal practice elsewhere.

 

I came across a photograph of an example (with both arms off) at Leiston on the Aldeburgh branch which rather surprised me, but subsequent inquiries suggested that a few other examples existed.

 

I have always presumed that it resulted from an S&T engineer who had trained and worked in the north east taking up a position elsewhere, presumably Leyton in this example, and specifying that both arms should be worked without realising that the practice was normally only used in the north east.

 

I wouldn't advise incorporating into a model of anywhere outside the north east (unless you were building a scale model of Leiston, of course) as it would be bound to raise eyebrows.

Edited by bécasse
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  • RMweb Gold

....when clearing subsiduary signals the main aspect remains at danger....the clearing of the subsiduary authorises the passing of the main aspect at danger....route knowledge and/or assocated letters tell one what to expect and how to proceed. At least latterly C, W and S were those letters....C = calling on, W = under the warning and S = shunt ahead. All movements to be made at caution ready to stop short of any obstruction.

 

Dave

No help with the original question sorry but as an aside ive never seen a W indication but was reliably informed by the signaller at severn bridge a couple of weeks ago that their signals protecting the platforms have the W indication as well as C, he said he had to use the W indication the week before when he was unable to pull off the main arm for platform 4 as the track circuit was showing occupied despite the platform being empty so he had to give a W to warn the train (for some reason he was unable to pull off the C indication either) he did explain why but the reason escapes me at the mo!

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Thankyou all. I understood that part of the lner interlocked the stop dignals such that one in rear could not be pulled off unless the one in advance was, thus the use of more calling on signals.

 

So outside that both a main and a subsidiary signal would not normally be off together, and pulling the main off would lock the subsidiary on, and ( having put both levers normal) pulling the subsidiary off would lock the main on.

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While I don't wish to confuse people for the sake of it, I feel that there is possible confusion here with the 'running shunt' situation.

 

For those not in the know this is where we arrange the signalling such that any shunt signals between two main signals have to be cleared to the proceed position before the rearmost main signal can be cleared to a proceed. This is to ensure a driver never gets into the situation where he passes a shunt signal at danger and is something that can still be seen today with multiple aspect signalling and colour light shunt signals.

Edited by phil-b259
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Ok I am confused now. How are these cases distinguished from the use of calling on or other subsidiary signals? Is this a modern signalling change?

 

I realise I don't actually know what a " running shunt " is. A shunt in the normal direction? Can you enlighten me?

 

Regards

Edited by ColHut
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  • RMweb Gold

No help with the original question sorry but as an aside ive never seen a W indication but was reliably informed by the signaller at severn bridge a couple of weeks ago that their signals protecting the platforms have the W indication as well as C, he said he had to use the W indication the week before when he was unable to pull off the main arm for platform 4 as the track circuit was showing occupied despite the platform being empty so he had to give a W to warn the train (for some reason he was unable to pull off the C indication either) he did explain why but the reason escapes me at the mo!

That is correct - they do have a 'W' indication (hence the multiple options on the Reading stencils (unless they've been replaced?).  I was told a good many years by a Reading Locking Engineer who helped install the new frame at Severn Bridge Jcn that the Warning signals dated from that time - late 1950s/very early 60s.  I presume that prior to that

 

You'd have loved Reading Jim - West Main's Up Advance Starting signals could - in addition to full clear of course - also show either C, or W or S partially reflecting the fact that East Main could accept trains over at least one of the Up Lines in 5 different ways in normal working; a full house.

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Ok I am confused now. How are these cases distinguished from the use of calling on or other subsidiary signals? Is this a modern signalling change?

 

I realise I don't actually know what a " running shunt " is. A shunt in the normal direction? Can you enlighten me?

 

Regards

 

A running shunt is a shunt is best described as a shunt signal on a main running line (as opposed to a siding) that requires to be operated to give a proceed indication before certain main running signals can be cleared to a proceed.

 

Imagine you have the following signals and trains pass them in this order

 

(1) Main running Signal & (2) Subsidiary Signal (i.e. a shunt signal) on the same post

(3) Ground Shunt Signal

(4) Main running Signal

 

Lets imagine that signal (1) is showing a proceed indication and signal (3) is at danger. The driver passes signal (1) as he is entitled to do but finds the next signal (3) telling him to stop. This could be confusing as according to signalling principles, signal (1) can only be cleared if ALL the track between signals (1) and (4) is clear of trains and all points are set correctly and as such there is no reason for a train to stop between (1) and (4).

 

To prevent confusion therefore we arrange the signal interlocking such that signal (1) is prevented from showing a proceed indication unless signal (3) is pulled off to a proceed first.

 

If a shunt move is taking place then signal (3) can remain at danger and the subsidiary signal (2) will be used to authorize movements up to it. Naturally signal (1) remains at Danger

 

Normally you would only get signal (1) OR signal (2) showing a proceed at any given time - however as indicated in this thread the NE region favoured the setup where if (1) was showing a proceed so would (2). It should be noted however that this still doesn't change the fundamental principle that if (1) is shown a proceed then (3) must also be showing a proceed.

Edited by phil-b259
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  • RMweb Gold

Ok I am confused now. How are these cases distinguished from the use of calling on or other subsidiary signals? Is this a modern signalling change?

 

I realise I don't actually know what a " running shunt " is. A shunt in the normal direction? Can you enlighten me?

 

Regards

The only way i can relate the description to a real life situation is what i would call a 'proving dummy', where there are ground signals between main aspects, crewe has a few of them such as coming from the potteries line into the station you get main aspect with a platform number in a stencil box but there are 2 position lights before you get to the platform that are both 'off', one is a multi spad though from errors made during 'proper shunts' out of the carriage shed as it were

 

EDIT: posted at the same time phil posted his explanation!

Edited by big jim
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How are these cases distinguished from the use of calling on or other subsidiary signals? Is this a modern signalling change?

Subsidiary signals, whether call on, shunt ahead or warning are located together with a main signal that they are subsidiary to, they don't have a stop aspect of there own as that is provided by the main signal red.

Running shunts are just stand alone shunt signals, as they have a stop aspect they need to be cleared for trains running on main aspects to pass them. Previously some railways avoided clearing running shunts by using a different  (non-red) lamp in them.

Keith

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Perhaps I can use a practicle example from SVR to show how a running dummy is used. At Kidderminster in the up direction there are facing points splitting the up/down main from the up/down loop. The splitting bracket is about 400 yards in rear. This allows a loco to run round stock in main or loop. The bracket tels which route you take but at the points a single running dummy proves the points set and locked . The next signal is the gantry. Amain signal can be cleared for the platform which requires negotiation of the facing points between platform road and run round loops. Arunning dummy is provided on both lines at the platform/run round lines to prove the points locked. The running dummy is also useful in that to run round the loco only needs to cclear the dummy not the main signal

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  • RMweb Gold

A running shunt is a shunt is best described as a shunt signal on a main running line (as opposed to a siding) that requires to be operated to give a proceed indication before certain main running signals can be cleared to a proceed.

 

Imagine you have the following signals and trains pass them in this order

 

(1) Main running Signal & (2) Subsidiary Signal (i.e. a shunt signal) on the same post

(3) Ground Shunt Signal

(4) Main running Signal

 

Lets imagine that signal (1) is showing a proceed indication and signal (3) is at danger. The driver passes signal (1) as he is entitled to do but finds the next signal (3) telling him to stop. This could be confusing as according to signalling principles, signal (1) can only be cleared if ALL the track between signals (1) and (4) is clear of trains and all points are set correctly and as such there is no reason for a train to stop between (1) and (4).

 

To prevent confusion therefore we arrange the signal interlocking such that signal (1) is prevented from showing a proceed indication unless signal (3) is pulled off to a proceed first.

 

If a shunt move is taking place then signal (3) can remain at danger and the subsidiary signal (2) will be used to authorize movements up to it. Naturally signal (1) remains at Danger

 

Normally you would only get signal (1) OR signal (2) showing a proceed at any given time - however as indicated in this thread the NE region favoured the setup where if (1) was showing a proceed so would (2). It should be noted however that this still doesn't change the fundamental principle that if (1) is shown a proceed then (3) must also be showing a proceed.

That needs a bit of correction Phil - the North Eastern Railway used the arrangement described above by Micknich.  As far as I know - from every signal which I have ever seen - it has never been used in colour light practice in that part of the world and it probably only survived on semaphore signals worked by lever frames which had not been relocked, Micknich can no doubt confirm one way or the other.

 

I think that generally running shunts were relatively uncommon in semaphore signalled installations which is logical when you think that there was generally a lack of facing points except in the most complex of track layouts.  They started to become more common with the start of 1960s rationalisation, as facing points were also becoming more common of course.  In many cases, such as that mentioned by Dave Scott (and I have specified them into several schemes) they have been used for operational convenience to save runround or shunting moves having to go back the full distance in rear of the relevant running signals and this is in many respects is something which the use of track circuit locking of facing points has allowed to develop.

 

Incidentally running shunts should not be confused with co-located shunts at running signals - as explained by Grovenor and illustrated by Micknich they are totally separate standalone signals.

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That needs a bit of correction Phil - the North Eastern Railway used the arrangement described above by Micknich.  As far as I know - from every signal which I have ever seen - it has never been used in colour light practice in that part of the world and it probably only survived on semaphore signals worked by lever frames which had not been relocked, Micknich can no doubt confirm one way or the other.

 

I think that generally running shunts were relatively uncommon in semaphore signalled installations which is logical when you think that there was generally a lack of facing points except in the most complex of track layouts.  They started to become more common with the start of 1960s rationalisation, as facing points were also becoming more common of course.  In many cases, such as that mentioned by Dave Scott (and I have specified them into several schemes) they have been used for operational convenience to save runround or shunting moves having to go back the full distance in rear of the relevant running signals and this is in many respects is something which the use of track circuit locking of facing points has allowed to develop.

 

Incidentally running shunts should not be confused with co-located shunts at running signals - as explained by Grovenor and illustrated by Micknich they are totally separate standalone signals.

 

When I said NE region I was speaking geographically rather than company speaking (though it seams the NER practice did occasionally migrate under LNER auspiciousness as people moved around in the 20s & 30s). I also have never seen any reference to the practice carried across to colour light signalling, even in the North East region (of the UK).

 

While semaphore running shunts (or running dummy in SR parlance) may not be common they were specifically installed on at least one Heritage Railway as it increases flexibility - indeed thinking about it logically bi-directional lines / loops are an obvious place where they might be found - though I do appreciate that bi-directional running tends to be a feature more common under power signalling schemes than mechanically signalled areas.

 

To be far though I never said running shunts were the same as co-located shunts at running signals, but in the case of North Easter Railway mechanical installations the visual effect is similar in the sense that in both situations the driver never passes a signal arm showing a stop indication.

Edited by phil-b259
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When I said NE region I was speaking geographically rather than company speaking (though it seams the NER practice did occasionally migrate under LNER auspiciousness as people moved around in the 20s & 30s).

The example I quoted at Leiston (in Suffolk) dated from the 1950s as I have seen photographic evidence that until the early 1950s the signal post in question didn't bear a subsidiary signal. I do think that the reason was exactly the same, the revised signalling being planned by someone who had previously worked in north east (and who had probably moved south on promotion).

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  • RMweb Gold

Very nice Mick - interesting to see that wholly white lights in ground position lights seem to have been the standard across the Northern (ex NER) Area of the LNER at that time (they were used elsewhere e.g. Leeds) while the Southern Area was using 'disc' (banner style) signals at the time and seemingly ignoring position lights.  One Company, two different railways ;)

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Thankyou all for your responses. I am slightly better educated.

 

Micknich, Thanks for the images. Para 2 on p 323 seems an odd way of putting the point though.

 

Para three on p323 presumably means any running shunts ahead must be interlocked with a subsidiary under a running signal with route indicator.

 

 

Talking of NERailway, why does it have miniature semaphore signals ( including on brackets) to control backwards shunting moves? See on John Hinson's excellent site Pontop and Aclington)

 

 

http://www.signalbox.org/diagrams.php?id=502

 

http://www.signalbox.org/diagrams.php?id=812

 

Regards

Edited by ColHut
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There were a number of places at single-line passing loops where a siding on (say) the up side of the Up loop would be connected at the 'down' end by crossing the Up loop on a  diamond and trailing into the Down loop, thereby avoiding a facing-point. In later years, when the railways became a little more relaxed about such matters, such trailing points + diamond would be removed and replaced by a facing connection off the Up loop. In such cases then the shunt leading into the siding would become a 'running shunt' for the stop signal in its rear (I hope all that's clear without a sketch!). Such things seemed to be quite common IMHO from about the 1930s onwards.

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