Signalling scheme help please!

[BluenGreyAnorak]

Hello folks,

 

I wonder if I could prevail on the collective for advice on signalling part of my layout under construction? I'm some way away from actually installing signals, but I'm designing one of the control panels and I'd like to make sure that the signals are integrated into it.

 

My layout is set in the Western Region in 1971.

 

The section that I'm working on is the most complicated part of the layout, including two main line junctions and access to an MPD.

 

 

The single track top left is the access to the fiddle yard and represents the 'rest of the world'. As the layout is a continuous run, the double track bottom left does connect with the double track labelled 'MAIN' at top right. However, concealed inside the tunnels on the left hand side is a second connection to the fiddle yard meaning that trains can run out and back. This second connection is shown on the control panel diagram below, although this obviously won't need signalling as it's non-scenic.

 

The double track labelled 'BRANCH' goes to a terminus station.

 

 

I've also included a PDF copy of the control panel diagram in case the picture above isn't clear enough.

 

In case further context is needed, there's an over all track plan within my layout thread HERE, although some details have changed slightly since that was posted.

 

I've read many threads on here about signalling and the most significant thing I've picked up is that there seems to be numerous ways of achieving the same ends! I'd therefore be very grateful for any suggestions with regard signalling this particular bit of my railway empire in as prototypical manner as is practical for the time and place.

Control Panel 1.pdf

[The Stationmaster]

I'm looking and thinking but do you want colour light signals or semaphore?

[BluenGreyAnorak]

Ah ha, I wasn't sure that there would be a choice

 

Although I may well regret it when I come to build the things, I really think I'd like to go for semaphores.

[BluenGreyAnorak]

Any more thoughts, Mike...?

[The Stationmaster]

Any more thoughts, Mike...?

 

Partly waiting to see what you what wanted - hopefully I'll now bounce something back sometime on Monday (needs a 'fingers crossed smiley I think) but it should be fairly simple with a bit of luck - the big problem is going to be how far apart/close together some features might be nut far from insoluble (I hope).

[The Stationmaster]

Here you go then - reduced to a fairly simple diagram (but not entirely in 'complete' diagram style) for what I have called 'Engine Shed Jcn' - just for my convenience The sketch shows what I would go for as the visible signalling on this part of the layout - i.e. it isn't a complete representation of everything the signalbox would be working as some of what would be needed/there in the prototype won't be there on your layout. To arrive at the size of the signalbox you need to know the number of levers and taht would be about 35 levers including 3 spares/spaces.

 

Now the sketch -

 

 

 

Reading from left to right we start with the only real problem which is siting the two signals protecting the fiddle yard junction as they would be difficult to see coming out of the tunnels - basically straight post signals but quite short is about all you can do from readily available kits/parts on the track spacing you have. Better than passable but not absolutely ideal.

 

The junction to the fiddle yard has a simple two doll splitting signal - both arms full size and could possiby be bracketed out to give better sighting round the signalbox.

 

The shed outlet signal is a yellow arm ground disc, there would also be a lineside 'phone (to the signalbox) near to it.

There is also a ground disc ('ordinary' red arm sort) reading back through the slip road into the depot so that locos can arrive from either direction.

 

The junctions is signalled with another two doll brackett - arms again of equal size and I have assumed the 'straight road' is the more important of the two - if it is of lesser importance than the other route it would have the arm at the lower elevation, irrespective of the curve in the junction.

 

Then we have two signal exactly the same (hence the little crosses to show where they go). On each the left hand doll reads to the through running line so has a full size arm while the right hand, lower elevation, arm reads to the 'siding' and is a short arm. Quite a typical WR arrangement for this sort of track formation.

 

Finally on the line up to the station I have included an Advanced Starting Signal with a lower arm Distant which is Fixed at Caution as you are approaching a terminus - with selective compression this should ideally be a train length beyond the junction fouling point but position also depends on the signalling at the terminus. I have also included an Outer Home Signal on the line from the the terminus to give some operational flexiibility.

I have drawn the signalbox where it ought to be -it could move a bit to the left to be more central between the two junctions but you would then definitely need to bracket out the fiddle yard junction signal (and yes, I have seen what the site is like from one of your pics - could be some interesting modelling for the signalbox base).

 

Hope that helps a bit

[BluenGreyAnorak]

Thanks, Mike. This more than just helps a bit - it's excellent! I really appreciate your time on this.

 

Inevitably though, I do have a few queries, which I've picked out below with some pics that include mocked up scenery to illustrate the points:

 

Reading from left to right we start with the only real problem which is siting the two signals protecting the fiddle yard junction as they would be difficult to see coming out of the tunnels - basically straight post signals but quite short is about all you can do from readily available kits/parts on the track spacing you have. Better than passable but not absolutely ideal.

I did suspect that this might be an issue. The picture below shows just how close the tunnel mouths will be to the first junction. Is it even vaguely prototypical to have signals there or should I just accept that they're off-scene?

 

 

The junction to the fiddle yard has a simple two doll splitting signal - both arms full size and could possiby be bracketed out to give better sighting round the signalbox.

Great. Understand that one.

 

The shed outlet signal is a yellow arm ground disc, there would also be a lineside 'phone (to the signalbox) near to it.

That one too.

 

There is also a ground disc ('ordinary' red arm sort) reading back through the slip road into the depot so that locos can arrive from either direction.

I need to check that I follow this one. Is this positioned by the slip so that loco's can arrive on the 'down' and then set back into the yard?

 

The junctions is signalled with another two doll brackett - arms again of equal size and I have assumed the 'straight road' is the more important of the two - if it is of lesser importance than the other route it would have the arm at the lower elevation, irrespective of the curve in the junction.

It'll actually be the other way around - the straight road is the branch off the main - but I get the idea.

 

Then we have two signal exactly the same (hence the little crosses to show where they go). On each the left hand doll reads to the through running line so has a full size arm while the right hand, lower elevation, arm reads to the 'siding' and is a short arm. Quite a typical WR arrangement for this sort of track formation.

I need to ask a bit more about the positioning here - particularly the one serving the 'up' main in the vee of the junction. Immediately after the junction both routes cross viaducts as shown below:

 

 

Given the close proximity, should this signal be positioned at the other end of the viaduct or actually on the viaduct itself? I guess in urban areas signals on bridges and viaducts must be quite common, but would that also be the case in deepest west country?

 

Finally on the line up to the station I have included an Advanced Starting Signal with a lower arm Distant which is Fixed at Caution as you are approaching a terminus - with selective compression this should ideally be a train length beyond the junction fouling point but position also depends on the signalling at the terminus.

There's actually quite a run from the junction up to the terminus - maybe 16-18ft as the line runs right around the room - so this signal could go on the other side of the viaduct. I'm sure I'll be asking about signalling for the terminus itself in the not too distant future

 

I have also included an Outer Home Signal on the line from the the terminus to give some operational flexiibility.

If the advanced starter on the 'down' is positioned beyond the viaduct, would this one go in a similar position on the 'up' or should be it as near to the junction as practical?

 

I have drawn the signalbox where it ought to be -it could move a bit to the left to be more central between the two junctions but you would then definitely need to bracket out the fiddle yard junction signal (and yes, I have seen what the site is like from one of your pics - could be some interesting modelling for the signalbox base)

Thanks Here's a clearer picture of just how much space there is, both between the junctions and between the main line and the baseboard edge...

 

 

And, for the sake of completeness, from the other direction too:

 

 

To arrive at the size of the signalbox you need to know the number of levers and taht would be about 35 levers including 3 spares/spaces.

That's really useful too, thanks. At Expo EM yesterday I found myself drooling over the minature brass signal levers that a couple of companies were offering and which were being used to great effect on Tower Pier. I'm not sure I'm ready to dive into making those just yet but it did reinforce my desire to make things as operationally correct as I can, even if the levers are represented by switches.

[TheSignalEngineer]

Stopping of trains on viaducts was avoided if possible, but there were many instances of signals on viaducts, a photo of a nice prototype at Oxley is shown in post #15 here. Sorry about the quality, it's a blow up from a negative from about 1966. Where a train stopped on a viaduct there was often handrailing on the top, especially if near a station, to stop passengers opening the door in the dark and going straight over the edge. Also, proximity of signals to the junction needs to be considered with regard to the amount of operational flexibility required.

 

Regarding your depot, do you want to be able to bring a loco off shed and go back towards the fiddle yard or along the main line to the left of the drawing? If so a bit of extra signalling may be required. Just to go to the fiddle yard would be quite simple, as there would only need to be a move from the ground signal along the Down Main to the single line. For a move to the Up Main, there would need to be a move from the yellow disc to a limit of shunt on the Up Branch, situated outside the Home signal. Mike will know best as to whether single or multiple discs would be the preferred method on the WR at that time.

[BluenGreyAnorak]

That's a very good point. Yes, it would be useful to be able to bring locos off shed both back to the fiddle yard and along the main line into the tunnel.

[The Stationmaster]

Inevitably though, I do have a few queries, which I've picked out below with some pics that include mocked up scenery to illustrate the points:

 

 

I did suspect that this might be an issue. The picture below shows just how close the tunnel mouths will be to the first junction. Is it even vaguely prototypical to have signals there or should I just accept that they're off-scene?

 

As far as the signals by the tunnel mouths are concerned you would - following usual (G)WR practice have some there - based on the mock-up the signal off the fiddle yard branch would be sited to the right of the line. The one off the Main would be left hand side and the curvature helps sighting. Both would be short posts - say with the arm no more than about 12'6" above rail level.

 

I need to check that I follow this one. Is this positioned by the slip so that loco's can arrive on the 'down' and then set back into the yard?

 

That is absolutely correct

 

I need to ask a bit more about the positioning here - particularly the one serving the 'up' main in the vee of the junction. Immediately after the junction both routes cross viaducts as shown below:

 

Given the close proximity, should this signal be positioned at the other end of the viaduct or actually on the viaduct itself? I guess in urban areas signals on bridges and viaducts must be quite common, but would that also be the case in deepest west country?

 

In view of the nature of the junction I would keep the signals as close as possible to the fouling point of the junction and if necessary to do that go along with the sort of situation illustrated in Signal Engineer's link - and that is WR, and it's not unusual for the WR. What would need to be avoided in such a situation is having that signal too far in rear of the points which could then result in Driver's accelerating too much before reaching the pointwork. There is an alternative but I have not suggested it as it would make things look 'over-signalled' in the vicinity of the loco depot and fiddle yard junctions in my opinion and it wouldn't be entirely typical of the way the Western did things anyway.

 

There's actually quite a run from the junction up to the terminus - maybe 16-18ft as the line runs right around the room - so this signal could go on the other side of the viaduct. I'm sure I'll be asking about signalling for the terminus itself in the not too distant future

 

Excellent - and that signal would look well beyond the viaduct I think.

 

If the advanced starter on the 'down' is positioned beyond the viaduct, would this one go in a similar position on the 'up' or should be it as near to the junction as practical?

 

The Outer Home should be 440 yards in rear of the Home Signal but that distance obviously has to be selectively compressed in the model world, even with the amount of space you have available. So yes, I think it would look ok at roughly the far end of the viaduct and could then be legitimately used as an Outer Home from an operational viewpoint. (and before anyone says anything I am at this stage in the game ignoring Western stop signal naming policy to avoid any confusion which might result between Home and Outer Home Signals).

 

That's really useful too, thanks. At Expo EM yesterday I found myself drooling over the minature brass signal levers that a couple of companies were offering and which were being used to great effect on Tower Pier. I'm not sure I'm ready to dive into making those just yet but it did reinforce my desire to make things as operationally correct as I can, even if the levers are represented by switches.

 

I think you will do well enough just having enough levers to work what's on the layout at that location Now see below on another point raised by some one else.

 

 

 

[The Stationmaster]

Regarding your depot, do you want to be able to bring a loco off shed and go back towards the fiddle yard or along the main line to the left of the drawing? If so a bit of extra signalling may be required. Just to go to the fiddle yard would be quite simple, as there would only need to be a move from the ground signal along the Down Main to the single line. For a move to the Up Main, there would need to be a move from the yellow disc to a limit of shunt on the Up Branch, situated outside the Home signal. Mike will know best as to whether single or multiple discs would be the preferred method on the WR at that time.

The problem with some signal engineers is that they actually ask the operators what they want before they design the signalling - I think I've just come across another one

 

It is of course a very good point and one I didn't bother with because what I would regard as the essential for it is not there - a trailing crossover, and there clearly isn't room for one. But it seems to be a facility which is needed so the way to do it is as Signal Engineer suggests and put a Limit of Shunt board in rear of the Home Signal on the route coming from the station.

 

The question of double discs is to some extent a matter of period - after WWII the GWR put in a number of new frames with single discs only, probably in order to save money when there wasn't much about while in the 1930s they had used double, or multiple discs, on similar layouts. The Western Region carried on with the post-war GW practice and generally used single discs in new work except when they were doing partial alterations at 'boxes with double/multiple discs where they normally tried to continue the practice. So to some extent you need to decide when your layout was signalled/when the lever frame was installed. For simplicity I would go for post war (and I have included a yellow disc which makes the ground disc arrangement post 1950 in any case), you can then go and have some multiple disc amusement at the terminus, or your other modelled area, should you want to. But it is your railway so the choice is yours.

[TheSignalEngineer]

The problem with some signal engineers is that they actually ask the operators what they want before they design the signalling - I think I've just come across another one

 

 

Not quite, Mike. My preferred M.O. was to sketch out my ideas then go for a cup of tea in the signal box and look for ways that the proposed layout created problems. The difficulty with actually asking the Divisional Operators first was that they wanted everything and priced the job out of sight.

 

About 35 years ago I had a bit to do with developing the system of Outline Project Specifications, which on our patch were produced by us then signed off by the Operators. This was intended to confirm that we both understood each other and that our estimated costs/their budget were close enough together before the proposal went on to the next stage.

[WillCav]

The shed outlet signal is a yellow arm ground disc, there would also be a lineside 'phone (to the signalbox) near to it.

 

I have a query on the Staionmaster's yellow disc.

 

I know the basic idea on the yellow discs but what stops a move from the engine shed towards the yellow disc whilst a signalled train is travelling from the main lines into the depot area? I assume there is some procedures or rules that stop this. I am not criticising - I am trying to get a wider understanding of the subject.

 

Would an alternative option be to change the yellow disc to a 'normal' one and plant another to apply to the engine shed / headshunt roads on the tandem point? This would increase signaller workload slightly (1 extra lever / signal) but could be mitigated by opposing locking being omitted.

 

regards

 

Will

[The Stationmaster]

Not quite, Mike. My preferred M.O. was to sketch out my ideas then go for a cup of tea in the signal box and look for ways that the proposed layout created problems. The difficulty with actually asking the Divisional Operators first was that they wanted everything and priced the job out of sight.

 

About 35 years ago I had a bit to do with developing the system of Outline Project Specifications, which on our patch were produced by us then signed off by the Operators. This was intended to confirm that we both understood each other and that our estimated costs/their budget were close enough together before the proposal went on to the next stage.

 

I like that approach - on the Western the S&T were often complaining of inadequate specs from the operators although my usual procedure when were working up schemes or going for estimates was to give them a sort of draft SFD style sketch plus a note on headways etc which we could then sit and talk around to develop any ideas and requirements and that usually worked well. Others weren't so involved (possibly because they didn't get on with JMW, or rather he didn't get on with them) with one the best examples coming when John was given a very clear - for once - headway spec and he returned a suitable drawing which met the spec only to be asked why he had used 3 aspect signals instead of 4 aspect

[The Stationmaster]

I have a query on the Staionmaster's yellow disc.

 

I know the basic idea on the yellow discs but what stops a move from the engine shed towards the yellow disc whilst a signalled train is travelling from the main lines into the depot area? I assume there is some procedures or rules that stop this. I am not criticising - I am trying to get a wider understanding of the subject.

 

Would an alternative option be to change the yellow disc to a 'normal' one and plant another to apply to the engine shed / headshunt roads on the tandem point? This would increase signaller workload slightly (1 extra lever / signal) but could be mitigated by opposing locking being omitted.

regards

Will

 

What you really need to be asking is what stops the Signalman changing the points which would allow the yellow disc to be cleared or allow a loco in? In other words the line doesn't really belong to the Signalman but is under someone else's control as it is a siding (in most such circumstances) and the Signalman agrees with them when he can set the road - and is sometimes covered by some sort of Local Instruction (but I know of two very busy freight yard connections where it wasn't).

The alternative is indeed exactly as you suggest but it costs more, even with opposing locking omitted, and in fact doesn't make much difference although the Signalman might not have to do any more than make sure there are no movements before putting the signals to danger, resetting the points .... and getting them run through by a Driver who had seen the disc 'off' the last time he moved towards it and hadn't bothered to look again since then.

[BluenGreyAnorak]

Thanks very much for all of this, chaps. It's all good stuff.

 

I've been working my way through the various details and have updated my control panel diagram to reflect Mikes' sketch and our subsequent conversation about positioning as follows:

 

 

Regarding your depot, do you want to be able to bring a loco off shed and go back towards the fiddle yard or along the main line to the left of the drawing? If so a bit of extra signalling may be required. Just to go to the fiddle yard would be quite simple, as there would only need to be a move from the ground signal along the Down Main to the single line. For a move to the Up Main, there would need to be a move from the yellow disc to a limit of shunt on the Up Branch, situated outside the Home signal. Mike will know best as to whether single or multiple discs would be the preferred method on the WR at that time.

 

It is of course a very good point and one I didn't bother with because what I would regard as the essential for it is not there - a trailing crossover, and there clearly isn't room for one. But it seems to be a facility which is needed so the way to do it is as Signal Engineer suggests and put a Limit of Shunt board in rear of the Home Signal on the route coming from the station.

 

Following the comments above, I'd like to just pick up on the idea of loco moves 'off shed', if I may? Having thought about this a bit more there are actually four possible varitions of this movement as follows:

 

1. Onto the down main

2. Onto the down main but then heading up the branch to the terminus

3. Crossing over to the up main by setting back to limit of shunt and then reversing

4. As 3 but then returning to the fiddle yard via the single track branch

 

I can see how the yellow disc controls access out from the yard onto the main lines and, if I've understood everything correctly, the combination of the LOS board and the signals at P7 and P19 can control all four directions that can be taken. What I wasn't sure about was Mikes' comment about the need for a trialing crossover. As everything seems to be possible with the signals marked and the LOS, would the need for one be to reduce the amount of wrong line running or am I missing something? Mike's right that there isn't room for another separate crossover, although I could change the diamond crossing at the junction to a single slip if it would help? In fact, I nearly did that at the time I laid the junction but, following on from other conversations we've had about maintenance of these things in the real world I decided against it.

 

Similarly, you both mention the choice of single or multiple discs, but I'm not sure where you are meaning that these could be positioned or what they would do. Also, is there any reason why a loco couldn't return to the fiddle yard by going out onto the down and then reversing to run wrong line back to the single line junction? If not, would that need additional signalling, or is it just as easy to use the LOS on the up main as indicated in 3 above?

 

Finally, I'm going to really show my ignorance with a quick question about the yellow disc in the yard. That disc will be positioned at the toe of the three way point that gives access to the shed and the rest of the yard respectively. It occurred to me that when that disc is 'on', it will still be necessary to move past it to use the rest of the yard. Is that ok? Would the real people using such an arrangement understand that it only controls the main line access and just ignore it for moves within the yard?

[Grovenor]

Thanks very much for all of this, chaps. It's all good stuff.

 

I can see how the yellow disc controls access out from the yard onto the main lines and, if I've understood everything correctly, the combination of the LOS board and the signals at P7 and P19 can control all four directions that can be taken. What I wasn't sure about was Mikes' comment about the need for a trialing crossover. As everything seems to be possible with the signals marked and the LOS, would the need for one be to reduce the amount of wrong line running or am I missing something?

The prototype would, wherever possible use a trailing crossover in this situation, use of the LOS is an alternative where the trailing crossover cannot be fitted in. Incidentally you have shown the LOS in the wrong place, it has to be placed so that locos can get behind the home signals to reverse and then be signalled away in the up direction. To have the LOS where you have shown it another ground signal would be needed at points 16 to allow the locos to move up to the starter, and as a facing ground signal in the running line that will bring some complications of its own.

 

 

Mike's right that there isn't room for another separate crossover, although I could change the diamond crossing at the junction to a single slip if it would help?

 

That would eliminate the need for the wrong line moves and LOS and slips in such a position were sometimes used on the prototype, the maintenance issues you mention are largely a thing of the modern railway in the colour light era.

 

Incidentally your diagram should show the normal position of the double junction as set for the main line, even though it is the curved route.

 

 

Similarly, you both mention the choice of single or multiple discs, but I'm not sure where you are meaning that these could be positioned or what they would do.

 

Where a disc leads to more than 1 route then it is possible to use multiple discs, the top one would lead to the leftmost route etc. In your plan this only applies to the yellow disc which has routes to both up and down lines.

 

Also, is there any reason why a loco couldn't return to the fiddle yard by going out onto the down and then reversing to run wrong line back to the single line junction?

It would be unusual unless such moves were frequent enough that they would delay trains on the Up Main. Additional signalling would be required as there is currently no signal controlling access to the Branch from the Down line.

 

 

If not, would that need additional signalling, or is it just as easy to use the LOS on the up main as indicated in 3 above?

Better to use the LOS.

 

Finally, I'm going to really show my ignorance with a quick question about the yellow disc in the yard. That disc will be positioned at the toe of the three way point that gives access to the shed and the rest of the yard respectively. It occurred to me that when that disc is 'on', it will still be necessary to move past it to use the rest of the yard. Is that ok? Would the real people using such an arrangement understand that it only controls the main line access and just ignore it for moves within the yard?

That is why it is yellow, to allow yard moves to pass it in the on position.

Regards

Keith

[The Stationmaster]

Nothing really to add to that except the comment about the setting of the junction and what would, or could, be the normal lie of the points (i.e is it set for either the Main or the Branch?). By the time setting of this layout the Western was well on with Work Study observation on lever frames and was injecting both it and the much earlier practice of taking account of local traffic requirements into lever frame design if it was going to save money. Thus - irrespective of what the lines might be called - junction settings were increasingly designed in to minimise the number of lever movements and this would be (and in real life was) done if frames were significantly re-locked for any reason. So the junction here could well be set normal for the busiest route.

(And before anyone mentions it as a way of saving lever movements the normal Western design principles had both points in a double junction with the normal lie in the same direction, i.e both of them were set for the same route when the levers stood normal in the frame.)

[BluenGreyAnorak]

Thanks, both. That explains it all very nicely

 

With all of those points taken on board, I've revised my diagram as follows:

 

 

I've relocated the LOS board beyond the home signal and changed the lie of the junction to show it set for the main, as this will be the primary route.

 

I'll now have to turn my attention to wiring and interlocking, and ponder on the dilema of whether or not to plan for working ground signals...

 

In the meantime, I wonder if I could impose and ask for your signalling views on my terminus? Again, below are the track and control panel plans.

 

 

 

The double track approach connects directly to the 'branch' shown on the previous diagram and there's about 16 feet of layout track between the two.

[The Stationmaster]

Nice track layout but just to check - length of the longest train please (in number/type of vehicles) and are we still on semaphore signals?

[BluenGreyAnorak]

Ah ha, the layout was devised with the help of your good self some months ago

 

Platform 1 will be designated for parcels and should take the equivalent of 5 coaches.

 

Platforms 2 and 3 will each accept a 2+5 HST set or a loco + 6 MKI/II coaches.

 

Platform 4 is shorter, and I envisage that being used for 3 or 4 car DMU's.

[The Stationmaster]

Thought it looked good Type of signals??

[BluenGreyAnorak]

Sorry. Sempahore again, please.

[WillCav]

Is it too late to change the control panel design?

 

If not, I would suggest that:

 

1) Change the 'normal' lie of P7 to be to platform 2 and add a (cosmetic?) wide to gauge trap point in the storage road for trapping. P7 and the trap point would then work together as a crossover.

 

2) Change the 'normal' lie of P14 to be into platform 1 - this allows 14 & 15 to be worked together as a crossover (less levers in the box) and provides trapping for the stabling road.

 

I will have a look at the signalling but I am sure that someone else will beat me to it!

 

Regards

 

Will

[BluenGreyAnorak]

Absolutely not - it's just pixels on a CAD drawing at the moment. I'm more than happy to alter it to incorporate good suggestions! Will have a look at it later.

 

I'll add wide-to-gauge trap points to my working ground signal dilema