Signalling help on my simple 8x4

[Chris64B]

Hi all,

 

First up I shall have to admit to knowing very little about signalling and despite reading up a bit online I'm still a bit baffled so I'm throwing myself on your mercy with what should hopefully be fairly simple query for the collective forum knowledge to answer....

 

I'm refurbishing my old childhood layout for my children (and me!) to play with again and I'm enjoying getting stuck in (see thread link in my signature below). I'm well advanced re-laying the track and ballasting and I've been busy adding trackside details like point motors, location cabinets, trunking, point heaters and rebuilding the level crossing. This is all bringing the layout to life again but something that's always been conspicuous by its absence is any form of signalling!

 

The layout has a mid-1980's theme and I'm imagining that semaphores have been recently replaced with coloured light signals (and points are controlled by machine/motor rather than rodding from the signal box).

 

I've produced a simple plan below to illustrate the layout - as you can see it's pretty simple and not very prototypical (!) but I'd like to try and have some vaguely representative signalling where relevant and/or practical, as it's definitely something that's currently missing from the 'lineside look'. Hopefully that's set the scene enough but do let me know if you need any more info or 'back story'.

 

 

So my specific questions are as follows:

1. I assume there would be a signal at the ends of the up and down platforms? What sort of signal would be used?
    
2. I guess I don't really have the track length to add further home/distant signalling but I'm not sure?
    
3. How would the entry/exit to the yard and bay platform/siding (short - used for parcels only) be signalled?
    
4. How would the two crossovers be signalled if at all? Ground signals?
    
5. Does the level crossing require any signalling of its own? The barriers are fairly modern AHBs if that makes any difference?
    
6. How would the entry/exit to the incline up to the upper level be signalled? What sort of signal would be used?
    
7. Can you suggest the most suitable location for the signal box? I was thinking of locating it next to the yard entrance/bay platform/siding point. Unfortunately there isn't really enough room near the level crossing.

I hope that makes some sort of sense - do feel free to correct or add things as required as this is all fairly new to me!

 

Many thanks in advance!

 

Chris

[28XX]

1. Yes. Stop signals. Red / green

2. No keep it simple

3. A short post stop signal or a ground signal.

4. Yes. The one top right is a facing crossover, a trailing crossover might be more prototypical

5. There should be a stop signal with a feather route indicator applying to clockwise trains top right on the drawing, protecting the level crossing and controlling trains into the loop platform.

6. Depends on the traffic using it. Is it bi directional?

7. If it's an old former mechanical box, then yes, by the level crossing. Full barriers too in that case. If AHB, add floodlights and CCTV cameras and the box could be 30 miles away.

[TheSignalEngineer]

AHB crossings would not be appropriate in this situation. It would be full barriers. Depending on the position of the signal box they would be either directly worked of if remote supervised by CCTV.

[28XX]

Yes boss, I agree.

[Chris64B]

Brilliant thanks both, that's really helpful! Now I'm starting to understand the basic signalling practice I've read about as I can see it in context with my layout.

 

A couple of clarifications and follow on questions if I may....

• Re Q.6, yes the incline is bi-directional, as is the down line through the tunnel I guess, as a train can travel from the up line platform, use the facing crossing on the right hand side of the layout, proceed through the tunnel to the 'wrong line' against the normal flow then travel up the hill to the upper level. This probably complicates things, sorry!
   
• Re Q.7, why would AHBs be unsuitable in this situation out of interest? Is that current practice or would it be true of the 1980's?

 

I'm still struggling a bit with the yard entrance/exit signalling but I've had a go at adding some symbols to the diagram - not sure if they make any sense but I've tried to place them in the right locations with the orientation showing which way they will face and I've added some green arrows to show the direction of travel on each line.

 

 

Please feel free to make any amendments as necessary! A few of things I was less clear on are (question numbers continue from the original 7 to avoid confusion!):

 

Q8. On the down platform with the loop would the signals be mounted on separate poles or together on a shared pole or gantry?

 

Q9. Could the feather signal at the top right actually be a three aspect with a yellow caution to indicate the state of the stop signals at the end of the platform and whether or not a train could run through the station without stopping?
 

Q10. How far back from the toe of the point would a ground signal be placed, or would it pretty much be right on it?

 

Q11. I'm sure I've got the yard entrance/exit signalling wrong so would appreciate your thoughts on that.
 

Q12. Likewise, I'm uncertain about signalling for the bi-directional branch up and down the incline.

 

Thanks in advance for your input!

Chris

[Nearholmer]

I'm no signalling engineer, as I've made apparent here before, to my embarrassment, but ........

 

- Strikes me that two-aspect signalling is a slightly unlikely scenario for a 1980s replacement of semaphore in what looks like quite a bust area. I think I would have expected to see three-aspect, or if it is a really busy area, four-aspect.

 

- if trains can be routed from the inner-road platform to the outer-road bidirectional section, for instance to gain access to the route to the upper level, then I think the inner road "starter" needs a route indicator of some kind associated with it.

 

- the signal that has a "feather": wouldn't the "feather" more logically angle the other way, to indicate a slower route, over the crossover into the inner-road platform?

 

- if trains can enter the inner-road platform while travelling clockwise, do they all terminate there (maybe needs a fixed stop light), or can they also depart clockwise from that platform, in which case a "starter" is needed at the left-end of that platform, which becomes bi-di;

 

- depending how generous the provision of shunt signals is to be, I think there is a place for a yellow shunt-signal at the exit from the parcels bay, permitting moves into the head-shunt.

 

MIRSEs please correct my mistakes!

 

Kevin

[Chris64B]

- the signal that has a "feather": wouldn't the "feather" more logically angle the other way, to indicate a slower route, over the crossover into the inner-road platform?

 

- if trains can enter the inner-road platform while travelling clockwise, do they all terminate there (maybe needs a fixed stop light), or can they also depart clockwise from that platform, in which case a "starter" is needed at the left-end of that platform, which becomes bi-di;

 

Kevin

 

Hi Kevin,

 

Thanks for your input! Will let the experts answer your questions but to pick up on the two points above...

 

The feather route indicator was intended to show if the train was going to pull into the 'main line' down platform or 'take a left' into the 'slow' loop platform (always from a clockwise direction). We don't tend to use the RHS crossing to come into the inner-road/up platform in the way you describe so hopefully that makes things simpler!

 

Cheers,

Chris

[RailWest]

I find the facing connection into the yard rather unlikely - if trains runs straight into it, then does it have internal run-round facilties, or how else will it be shunted?

[Gwiwer]

Far more likely to have the yard entry as a trailing point rather than facing traffic emerging from the tunnel.  

 

Train emerges from tunnel, draws up to stop signal at the platform end (or short of it but clear of clearing point in the rear) and shunts back to the headshunt under control of a doll - position light - at the platform end.  Then shunts ahead under yard control to where required.

 

Your two platform starters could be either mounted on one bracket arm or two separate posts according to local requirements and sighting.  They could even be on a gantry.  Signal siting depends to a great extent on the unique local conditions.

 

You have a stop signal to control exit from the incline to the main line and within the scope of this layout nothing else is really needed on that line in either direction.  What you do need is a trap point between that signal and the main line to divert any runaways to the left and (hopefully) clear of the main line.

[Chris64B]

I find the facing connection into the yard rather unlikely - if trains runs straight into it, then does it have internal run-round facilties, or how else will it be shunted?

 

Far more likely to have the yard entry as a trailing point rather than facing traffic emerging from the tunnel.  

 

Train emerges from tunnel, draws up to stop signal at the platform end (or short of it but clear of clearing point in the rear) and shunts back to the headshunt under control of a doll - position light - at the platform end.  Then shunts ahead under yard control to where required.

 

Thanks chaps - I'm stuck with the layout as is now so happy to accept that it's a bit of a compromise in that area!

 

In practice it seems to work fine - any trains running clockwise on the down line can back into the yard directly and the loco is free to move away into the shed or headshunt/elsewhere. Trains running anti-clockwise on the up line emerge from the tunnel and have two choices, either run to the end of the platform and have their coaches/wagons shunted away from there or go directly into the yard (it does mean the loco is trapped until the shunter comes to the rescue to remove the wagons).

 

If the yard entry was a trailing point would ther problem just be reversed and the trains on the clockwise down line would be affected in the same way? Or have I got the wrong end of the stick?! Would be great to see a sketch of what you mean if poss?

 

Your two platform starters could be either mounted on one bracket arm or two separate posts according to local requirements and sighting.  They could even be on a gantry.  Signal siting depends to a great extent on the unique local conditions.

 

You have a stop signal to control exit from the incline to the main line and within the scope of this layout nothing else is really needed on that line in either direction.  What you do need is a trap point between that signal and the main line to divert any runaways to the left and (hopefully) clear of the main line.

 

Thanks for those answers Gwiwer! Good thinking about the trap point - I'm still able to add that in as the track work to the upper level is still to be re-laid.

[LongRail]

Chris,

 

I would lose the ground position lights in the yard just as likely to be under control of a shunter giving instructions. You could leave the position light on the exit.

 

Not sure you would have position lights protecting the cross overs on a mainline, the signals would be some distance back depending on line speed there is an overlap beyond a signal which will stop sHort of the points.

 

Have you thought about how you are going to,operate the signals I use heathcote electronics signal modules which atumate based on trains moving past each signal.

 

Have you considered motorising the level crossing by the way again there are products around to do this

[phil-b259]

 

• Re Q.7, why would AHBs be unsuitable in this situation out of interest? Is that current practice or would it be true of the 1980's?

 

The rules relating to AHBs are very strict. Please remember they are NOT interlocked with signals and operate on a stand alone basis.It doesn't matter what era you are portraying the key ones have been in place since the mid 1960s and continue to be valid today.

 

It is a statutory requirement* that 80% of trains MUST pass over the crossing within 30 seconds of the crossing sequence starting. This is to try and prevent drivers and pedestrians getting fed up and swerving round the barriers - which MUST only close off half the road (thus providing an escape route for trapped persons - remember the crossing operation is automatic)

 

If the statutory requirements cannot be met due to an adjacent station or large speed differentials between train types then other measures MUST be taken to ensure compliance. In the former case this is typically done by fitting a 'Stopping' or 'Non Stopping' selection switch in the signal box and adding extra signal controls so that the 'strike in' point for the crossing moves. Naturally this has to be fail safe so if it goes wrong and the barriers stay down for longer with a stopper rather than compromising the safety of users should a non stopping train approch. If the speed differential is too large however then it may simply be a case of applying a lower speed limit at that location than otherwise would be the case.

 

Also you need to remember that the more routes you have leading up to an AHB crossing, the more complicated the signalling equipment gets.

 

 

* I may have the exact numbers wrong - but I am doing this from memory.

[phil-b259]

I'm no signalling engineer, as I've made apparent here before, to my embarrassment, but ........

 

- Strikes me that two-aspect signalling is a slightly unlikely scenario for a 1980s replacement of semaphore in what looks like quite a bust area. I think I would have expected to see three-aspect, or if it is a really busy area, four-aspect.

 

-

 

Indeed - Anything with this sort of complexity (even if it did retain the lever framed signal box working colour light signals and motorised points) would use 3 / 4 aspect signalling. Two aspect colour lights are actually pretty rare in station environments - 3 aspect platform starters (even if they read onto a section set up with two aspect red / green stop and yellow green distants) would be more prototypical

[RJS1977]

Shouldn't the position light signals near the top left crossover be the other way round (i.e. to signal routes over the crossover?

 

The yard exit could even have a "Stop and await permission" board rather than position lights, and the permission given would also apply to using the crossover.

[28XX]

Shades of Leamington and Stourbridge in the period, where 2 and some 3 aspect took over from semaphore incrementally.

 

Q8. Seperate posts. What you have drawn could be interpreted as a junction signal with 2 equal speed routes. Except New Street, where space was at such a premium it was done on one post.

[28XX]

Yes boss, I agree.

Well he was my boss.

[TheSignalEngineer]

Well he was my boss.

A very long time ago.

[roythebus]

Unless someone else has mentioned it, you'll also need a stop signal on the left end of the inner platform to let trains escape to the outer circuit, and a shunt signal to let them wrong road onto the inner circuit.

[LongRail]

Don't forget a model railway is very condensed so visually you need to be carefull that providing too many signals can start to look like street lights. I would suggest a degree of modellers license should be exercised

[Gwiwer]

Don't forget a model railway is very condensed so visually you need to be carefull that providing too many signals can start to look like street lights. I would suggest a degree of modellers license should be exercised

 

 

I agree.  Compromise within sensible bounds is fine.  SIgnalling must obey the basic rules otherwise it is meaningless and might as well not be there but there is no room here for full block sections with distants, outer and inner homes and advanced or section signals.

 

Even on my layout which has a 34-metre circuit there are compromises.  Some trains are longer the distance between two signals and the overlaps are impossibly short.  One section has a starter but no section signal largely because there is nowhere sensible to put it.  Notwithstanding that the layout has been applauded more than once for "correct signalling".  

[TheSignalEngineer]

To make signalling meaningful it is also necessary to think what would be off-scene. This may determine the configuration of a particular signal, e.g. a platform starter may be a 3-aspect as there could be a section signal out of sight which is needed for the convenience of not shunting into the forward section to use a crossover, 

another point to consider is that it would not be allowed to run from a green straight to a red aspect. A red/green signal should be followed by a yellow/green distant unless there are special controls which require the second signal to be cleared before the first signal in the direction of travel.

[The Stationmaster]

I agree.  Compromise within sensible bounds is fine.  SIgnalling must obey the basic rules otherwise it is meaningless and might as well not be there but there is no room here for full block sections with distants, outer and inner homes and advanced or section signals.

 

Even on my layout which has a 34-metre circuit there are compromises.  Some trains are longer the distance between two signals and the overlaps are impossibly short.  One section has a starter but no section signal largely because there is nowhere sensible to put it.  Notwithstanding that the layout has been applauded more than once for "correct signalling".  

 

If it has just one Stop signal (be it Home or Starter) then it has a Section Signal - simples.

[Chris64B]

Wow, thanks all for taking the time to respond - really valuable stuff! There was me thinking this would be simple!

 

I've picked up on a few specific points quoted below and revised the diagram (see further down)....

 

You have a stop signal to control exit from the incline to the main line and within the scope of this layout nothing else is really needed on that line in either direction.  What you do need is a trap point between that signal and the main line to divert any runaways to the left and (hopefully) clear of the main line.

 

Good plan - Catch point added and the two aspect signal retained to protect the main line from runaway trains coming down the hill (Thomas and Friends style!)

 

 

I would lose the ground position lights in the yard just as likely to be under control of a shunter giving instructions. You could leave the position light on the exit.

Not sure you would have position lights protecting the cross overs on a mainline...

Have you thought about how you are going to,operate the signals I use heathcote electronics signal modules which atumate based on trains moving past each signal.

Have you considered motorising the level crossing by the way again there are products around to do this

 

Thanks - Have removed the ground signals on the crossovers but still uncertain about the area around the yard entrance/head shut and parcels bay?!

 

I was just planning manual control as the layout is DC but will check out the Heathcote modules, I have seen them mentioned elsewhere too. And yes, motorising the LC barriers could be a fun project in the future!

 

 

The rules relating to AHBs are very strict. Please remember they are NOT interlocked with signals and operate on a stand alone basis.It doesn't matter what era you are portraying the key ones have been in place since the mid 1960s and continue to be valid today.....

 

...and...

 

Indeed - Anything with this sort of complexity (even if it did retain the lever framed signal box working colour light signals and motorised points) would use 3 / 4 aspect signalling. Two aspect colour lights are actually pretty rare in station environments - 3 aspect platform starters (even if they read onto a section set up with two aspect red / green stop and yellow green distants) would be more prototypical

 

Many thanks Phil, that's really informative - haven't been able to find much info about the AHBs before. I might apply a bit of modellers licence and keep them for now but will bear it in mind.

 

Have updated the diagram with some three aspect signals, hopefully in the relevant places?!

 

 

Shouldn't the position light signals near the top left crossover be the other way round (i.e. to signal routes over the crossover?

 

The yard exit could even have a "Stop and await permission" board rather than position lights, and the permission given would also apply to using the crossover.

 

Yes you might be right but I've removed them for now for simplicities sake but I'm still a bit puzzled about the yard entrance/exit signalling!

 

 

Q8. Seperate posts. What you have drawn could be interpreted as a junction signal with 2 equal speed routes. Except New Street, where space was at such a premium it was done on one post.

 

Thanks - have updated them accordingly. I guess they would be placed to the left of the track?

 

 

Unless someone else has mentioned it, you'll also need a stop signal on the left end of the inner platform to let trains escape to the outer circuit, and a shunt signal to let them wrong road onto the inner circuit.

 

Thanks, but not sure I quite follow you? Maybe have been a typo with two 'inners' described?

 

 

Don't forget a model railway is very condensed so visually you need to be carefull that providing too many signals can start to look like street lights. I would suggest a degree of modellers license should be exercised

 

Very good point - it's all on an 8x4 ft board of course! I'm really after something that is reasonably realistic within the context of the roundy roundy nature of the layout! I'd feel silly randomly installing signals without any knowledge of what they are for so this thread has been invaluable!

 

 

To make signalling meaningful it is also necessary to think what would be off-scene. This may determine the configuration of a particular signal, e.g. a platform starter may be a 3-aspect as there could be a section signal out of sight which is needed for the convenience of not shunting into the forward section to use a crossover, 

another point to consider is that it would not be allowed to run from a green straight to a red aspect. A red/green signal should be followed by a yellow/green distant unless there are special controls which require the second signal to be cleared before the first signal in the direction of travel.

 

Thanks, good point - when we are playing trains they usually disappear into the tunnel as if they've 'gone on a long journey' (as the kids say) so I think making some of the main line signals 3 aspect makes sense.

 

 

So....here's version two...

• Ground signals removed on main line cross-overs.
   
• Main line signals changed to three aspect to suggest busier lines and some degree of off scene route and signalling.
   
• RH feather added to inner anti-clockwise platform signal to show that a route may be set to use the RHS cross-over to run wrong line through the tunnel and onto the branch line up the hill.
   
• Catch point added and the two aspect signal retained to protect the main line.
   
• I am still puzzled by how the yard entrance/exit and parcels bay ought to be signalled - see the big red question marks! How would something like my Class 128 DPU visiting the parcels bay be signalled in and out? And same for a train or light loco using the yard?

 

Phew! I'm exhausted now! All this for a model railway - good fun though!

 

Thanks again for your advice!

Chris

[Gwiwer]

At the two question marks nothing is essential in your diagram

 

Top left : Yard entry can be controlled by assumed off-scene signals one for each main running line.  That for the outer loop can be assumed to also control access to the incline.  If you want to be precise then it could be a three-position colour light with a right-hand feather for the incline, left-hand feather for approach to the inner loop platform road and a subsidiary position light (doll) for the yard entry.   

 

Lower right : This appears to be for entry to the parcels siding or yard.  The signalled route off the main lines would by default be one or other and probably the siding.  You can either place a "STOP and await instructions" board at the yard entry or assume your position lights off-scene also defined which of the routes was cleared.  It is normal for there to be a requirement to stop before entering a yard because it defines the end of fixed signalling and the start of local control by a yard supervisor, shunter or other person on the ground.  No fixed signal is essential here either.

 

The two position lights shown should be placed to control exit from the siding and from the yard (so more or less side-by-side) and the head-shunt acts as the trap point in this case.  As the inner loop is unidirectional any shunt movement onto this line must be restricted by a LIMIT OF SHUNT board, sign or permanent double-red doll.  Clearing the doll at either the siding or the yard exit then gives authority to proceed to the LoS or outer loop as far as the next stop signal.  A basic route indication would be used to indicate which of the two possibilities was offered. 

 

What is required is a means to permit moves from siding or yard to headshunt.   In the days of rotating ground signals one stacked above the other would have been employed to differentiate the route offered on the basis of top = left, centre = ahead, bottom = right.  Using colour light ground dolls it is possible to give a route indication by means of miniature feather (an angled white line displayed in a small square pane) or alpha-numerically but such things are too complex for a small layout.  We can assume that if the point to the headshunt is controlled by the signalbox, fully interlocked and set to that route then by definition there is no access to the main lines and any move may be authorised by the yard-master.

 

On a small but often-mentioned matter the "catch point" you have now marked and labelled is a "trap point".  The difference lies in that a trap is there to catch movements in the "right" direction (passing the signal and running towards the main line as here) while a catch point traps them in the wrong direction (rolling back from a siding onto a running line as an example).  

[Chris64B]

Brilliant! That's really helpful, thanks for explaining it so clearly, that all makes sense! I'll have a go at tweaking the diagram tomorrow.

 

In the meantime, here's a virtual pint!

 

Cheers, Chris