Single line signalling (and trap point) questions

[Railfreight1998]

Hello everyone

 

I'm wondering if anyone can tell me what signalling would be required for the track plan shown. The layout represents a single track section of the cumbrian coast line in the late 1980s.

I think I am right in that 2 ground signals would be needed at A and B to control entering and exiting the headshunt, but I am presuming that a main signal would also be needed at A otherwise the ground signal would be controlling main line traffic as well - is this correct? Also, would any signalling be needed in the down direction (ie at C) to protect the yard entrance?

Finally, am I also correct in saying a trap point would be required at B, as the point before it is hand operated, and where would the ground signal be placed in relation to this?

 

Apologies for all the questions, but my knowledge of signalling is pretty limited.

 

Thanks in advance

[Compound2632]

23 minutes ago, Railfreight1998 said:

Finally, am I also correct in saying a trap point would be required at B, as the point before it is hand operated,

 

I don't see why the point in question is hand operated as it forms a crossover with the point on the running line. Surely they would be worked together? Thereby providing the necessary protection for the running line with the minimum of equipment.

[Railfreight1998]

27 minutes ago, Compound2632 said:

 

I don't see why the point in question is hand operated as it forms a crossover with the point on the running line. Surely they would be worked together? Thereby providing the necessary protection for the running line with the minimum of equipment.

Thanks for your reply.

I had thought that as it is providing access to the private railway it would be independently worked, but looking at it now working it as a crossover does make more sense.

[Compound2632]

3 minutes ago, Railfreight1998 said:

Thanks for your reply.

I had thought that as it is providing access to the private railway it would be independently worked, but looking at it now working it as a crossover does make more sense.

 

From your sketch, the position of the gate puts the crossover and headshunt on the railway side of the boundary.

[Grovenor]

No ground signals required, just a ground frame to operate the crossover. The ground frame released by the single line token. Once released handsignals used for the movements. If the train needs to be shut in the sidings for other trains to pass then you need a hut with a token instrument.  If the Electronic token block was already in use at your date the principles would be the same but the groundframe electrically released from the ETB system and there would be a hut for that.

Edited May 13, 2020 by Grovenor

[Railfreight1998]

Thanks Grovenor

The supposed location of the modelled scene is immediately before the track becomes double to the left hand side of the scene (in the up direction), being very loosely based on Corkickle. As the siding entrance is fairly close to the signal box, and it would see a good amount of use, would have been easier to have the points worked by the box instead?

 

http://www.lymmobservatory.net/railways/sbdiagrams/corkickle_no_1_q65.jpg

Attached is a track plan from the Corkickle no. 1 box, with the bottom right hand corner being what I am representing. Would it be reasonable to have the outer home signal (33 on the plan) positioned before the siding, given I will be placing what are signals 32 and 42 to the extreme left of my model? Obviously the distance between them would be extremely compressed, but a retaining wall will at least partly mask this.

 

Thanks again

[Grovenor]

Given that 33 is 440 yards from 32 and your layout probably is not that long you would need 33 to be on the extreme right of your model, if not offscene. Looking at the box diagram your siding connection is most probably over the max distance for rodding worked from the box (350 yds) so I would still use a Ground Frame. But I note that the line to St Bees is worked by acceptance lever so the GF would have an electric release rather than a key token lock. The location is outside the section signal, 27 so trains going there would need ST Bees to accept them.

Edited May 14, 2020 by Grovenor

[Dungrange]

As Grovenor has said, I don't think there is a need for any signals on the layout as drawn (although I'm no expert).  There would obviously be a need to stop a train travelling in the down direction approaching a point set against it, but I'd expect that signal to be off-scene to the left at the end of your imaginary double track section.  That signal would provide authorisation to move into the single track section (in possession of the single line token), which means that there wouldn't be a need for another signal at C.

 

There would be a block signal for trains in the up direction, but I'd expect that to be at least a train length and an overlap distance from point A, which means that signal would be off the bottom of your plan.

 

The shunting in/out of the head-shunt wouldn't be signalled - all that would be required would be possession of the single line token.

 

As has already been said, there is no need for a trap point, because the crossover A & B would be operated by a local ground frame, which can only be unlocked by the train in possession of the single line token.  The single line token can only be released from the ground frame once the crossover has been set back to normal, so point B performs the trap function.

[Railfreight1998]

Thanks everyone

I think I may include the up block signal, but it will be at the very edge of the scenic section, as will the splitting home at the other end. I had hoped to be able to make use of the ground signals, but I should be able to put these in the storage yard (basically a photo plank representing a short section of workington yard).

[The Stationmaster]

31 minutes ago, Railfreight1998 said:

Thanks everyone

I think I may include the up block signal, but it will be at the very edge of the scenic section, as will the splitting home at the other end. I had hoped to be able to make use of the ground signals, but I should be able to put these in the storage yard (basically a photo plank representing a short section of workington yard).

It would make a lot of sense to put the Section Signal at/beyond 'C' on the drawing because that would help put the private siding inside Station Limits.  Putting the Down [Outer] Home Signal  further out, including potentially off scene although that isn't essential, would be even better  as it would make a lot of sense operationally and avoid the need to go through the procedure needed for a shunt onto the single line (i.e outside the Home Signal).

[Railfreight1998]

3 hours ago, The Stationmaster said:

It would make a lot of sense to put the Section Signal at/beyond 'C' on the drawing because that would help put the private siding inside Station Limits.  Putting the Down [Outer] Home Signal  further out, including potentially off scene although that isn't essential, would be even better  as it would make a lot of sense operationally and avoid the need to go through the procedure needed for a shunt onto the single line (i.e outside the Home Signal).

It's probably very clear, but I don't quite follow you there Stationmaster. Which signal are you referring to as the 'section signal'? As far as I can see the down direction (clockwise on the plan) starter (section signal?) would be before the line reduces to single track to the left of the scenic area.

[The Stationmaster]

46 minutes ago, Railfreight1998 said:

It's probably very clear, but I don't quite follow you there Stationmaster. Which signal are you referring to as the 'section signal'? As far as I can see the down direction (clockwise on the plan) starter (section signal?) would be before the line reduces to single track to the left of the scenic area.

The Section Signal is the one which controls the entrance to the next block section.  I assumed when the term 'block signal' was used that was what was meant, as it seems to imply, entering the block section, i.e. the Section Signal, in effect an Advanced Starting Signal.    But it appears that was not what you meant. and in fact you were talking about the Home Signal when you used the words 'block signal'.  (a Home Signal stands at the exit from a block section and marks the end of it).

 

So, having got that sorted, I'll try again.  You will need an Up direction stop signal at the toe, or pretty close it, of the points where the line goes from single to double.  As that point is not modelled in the area illustrated the signal would be off that section of your drawing.   Additionally iIt would be operationally advantageous to have an additional Up direction Home Signal further out, ie. off the bottom end of your drawing, to simplify the procedure needed to get a movement in position to access the siding as it could then be done with any reference to the Signalman at the opposite end of the single line section deending on the position of the Section Signal and the type of block working in use.

 

Similarly a Down direction stop signal - which would become the Section Signal if it is provided - could be provided at the bottom end of the drawing to act as limiting point to control shunting movements.  Such a signal is far from essential but tends to be provided in modern installations as an additional safeguard and of advantage if some types of block working are in use.

 

[Railfreight1998]

Thanks Stationmaster

I was indeed referring (erroneously) to the up outer home as a block signal. The situation you have described is pretty much exactly what I will do.

Am I right in saying if the crossover is controlled by the box then ground signals would probably be provided? If I have the box near to the point the line doubles, then the crossover would be within the maximum distance for point rodding, given the point is immediately left of the scenic section.

Edited May 15, 2020 by Railfreight1998

[Grovenor]

Which is getting a long way from Corkickle! But if you bring points A into the interlocking directly the Facing Point lock on A will  also be worked from the box. The home signal can be close to the toe of A, leave room for a lock bar unless you assume track circuited. The home signal will need a co-located shunt to enter the sidings and you will need a yellow shunt for coming out. Your outer home, as at Corkickle can be 440 yards back from the home so well off scene.

[The Stationmaster]

17 hours ago, Railfreight1998 said:

Thanks Stationmaster

I was indeed referring (erroneously) to the up outer home as a block signal. The situation you have described is pretty much exactly what I will do.

Am I right in saying if the crossover is controlled by the box then ground signals would probably be provided? If I have the box near to the point the line doubles, then the crossover would be within the maximum distance for point rodding, given the point is immediately left of the scenic section.

 

17 hours ago, Grovenor said:

Which is getting a long way from Corkickle! But if you bring points A into the interlocking directly the Facing Point lock on A will  also be worked from the box. The home signal can be close to the toe of A, leave room for a lock bar unless you assume track circuited. The home signal will need a co-located shunt to enter the sidings and you will need a yellow shunt for coming out. Your outer home, as at Corkickle can be 440 yards back from the home so well off scene.

You can do exactly as Grovenor has suggested - perfectly straightforward arrangement.

 

What that arrangement will not necessarily offer is total freedom with shunting movements as it will require a procedure to be carried out with the Signalman at the other end of the single line section.  If, as 'Grovenor' has suggested you also provide an Outer Home Signal 440 yards in rear of the Home Signal, and disc, which immediately protect the siding connection you avoid the need to carry out the procedure with the other Signalman.  In older track layouts providing an Outer Home Signal in this sort of situation was relatively uncommon but in the latter part of the last century it became increasingly used particularly where lots of shunts were made outside the protection of the Home Signal.  You'll also find it quite common on lots of so-called 'heritage' railways as it creates much greater flexibility and simplicity for shunting out onto the single line - not that such stations originally had anything like such additional signal provision.  

So in the 1980s an imagined Outer Home Signal is wholly justifiable.

[Flying Pig]

On 13/05/2020 at 16:15, Railfreight1998 said:

 

 

 

Non-signalling comment, but wouldn't the crossover make more sense the opposite way round?  Given the orientation of the exchange sidings and the lack of runround, the BR loco will always be at the Barrow end* and that gives access to the main with fewer reversals.

 

*presumably in one direction the train, or at least the wagons will reverse offscene at some convenient yard?

 

It is good to see a relatively simple layout being given space to breathe.

[Railfreight1998]

Based on the info everyone has provided, I think I now have a workable signal plan, a rough version of which is shown below. The area being modelled is within the dashed box.

The one thing I'm not sure about is the ground disc controlling the exit from the exchange siding onto the main line. I don't think it should be a yellow disc, as only industrial locos will pass it taking the upper line, but I could be wrong.

Flying pig - it's not clear on the plan but the headshunt is actually the exchange siding; one of the lines on the right hand board leads to the industrial loco shed, the other to a chemical plant (where Corkickle comes in). You are right in that trains can only shunt it in one direction, but I'm willing to make that compromise to have a better track-scenery ratio.

[Grovenor]

For locos, industrial or not, to pass the exit signal when not set for exit it needs to be a yellow disc, that's exactly what they are for.

BR territory BR rules whoever owns the loco. You did say 1980s not 1920s.

[Edwin_m]

Wouldn't there have to be a Down Starter with this signal layout?  Otherwise the disc on the siding exit is reading all the way to the next box.  

[The Stationmaster]

15 hours ago, Edwin_m said:

Wouldn't there have to be a Down Starter with this signal layout?  Otherwise the disc on the siding exit is reading all the way to the next box.  

Not necessarily.  There were plenty of not dissimilar situations where a disc signal from a siding read towards a section on both double and single lines.  However there was definitely a move in the latter part of the 20th century towards providing a Section Signal in advance of such connections as a sort of additional insurance to make extra sure that a shunt move coming out of such a siding didn't sail off into the section. So by the 1980s era there was probably more likely to be such a signal than not especially if it was regularly or frequently serviced siding.

 

Incidentally it makes much more sense for the siding access to be this way round that the other (as suggested by 'Flying Pig') and not just because of the way 'Railfreight' has developed his track plan.  The reason being that the propelling move on the running line will be wholly within Station Limits and towards a line running in the right direction.  If the propelling move were to be towards the single line section any breakaway could have potentially more serious consequences.  Although, as ever, a lot depends on the gradients - should there be any.

[phil-b259]

16 hours ago, Railfreight1998 said:

Based on the info everyone has provided, I think I now have a workable signal plan, a rough version of which is shown below. The area being modelled is within the dashed box.

The one thing I'm not sure about is the ground disc controlling the exit from the exchange siding onto the main line. I don't think it should be a yellow disc, as only industrial locos will pass it taking the upper line, but I could be wrong.

Flying pig - it's not clear on the plan but the headshunt is actually the exchange siding; one of the lines on the right hand board leads to the industrial loco shed, the other to a chemical plant (where Corkickle comes in). You are right in that trains can only shunt it in one direction, but I'm willing to make that compromise to have a better track-scenery ratio.

 

Technically you don't need a main signal at the points giving access to the siding. Signalling is expensive and signals will only be installed where there is a clear need - not simply because they look nice. In your case, a private siding is not the sort of thing that will require more than the bare minimum of expenditure.

 

The regulations require that any shunt signals located between two main running signals (i.e. the one on the right and the one on the left on your plan) MUST be pulled off to a proceed before the main running signal in rear (the one on your right) can show a proceed.

 

This is because as shunt signal at danger still means stop (unless it is acting as a subsidiary signal to a main arm) and any driver coming across a signal at danger is required to stop regardless of train type.

 

That said in view of a lack of working 4mm scale mechanical shunt signals the setup you have drawn would get round the problem of main line trains trains sailing past a stand-alone shunt at danger contrary to signing regulations.

 

 

Edited May 17, 2020 by phil-b259

[bécasse]

1 hour ago, The Stationmaster said:

There were plenty of not dissimilar situations where a disc signal from a siding read towards a section on both double and single lines.  However there was definitely a move in the latter part of the 20th century towards providing a Section Signal in advance of such connections as a sort of additional insurance to make extra sure that a shunt move coming out of such a siding didn't sail off into the section. So by the 1980s era there was probably more likely to be such a signal than not especially if it was regularly or frequently serviced siding.

 

 

I reckon that there must have been a specific instruction on the subject from the BRB c1959 because on the Southern, at least, a lot of dollies giving direct access from sidings to a block section were replaced by semaphores (with short, subsidiary, arms), while these were mainly red there were at least a dozen examples of yellow arms where yellow discs had existed previously. This obviously only happened where there was no advanced starting signal, but it was a lot cheaper to replace a dolly with a semaphore (no changes to the locking being required) than to install a new advanced starting signal (which would have required an extra lever and at least some changes to the locking).

 

Ironically, almost all the locations where the change was made became redundant within a couple of years or so as local goods yards closed.

Edited May 17, 2020 by bécasse

[The Stationmaster]

7 minutes ago, bécasse said:

I reckon that there must have been a specific instruction on the subject from the BRB c1959 because on the Southern, at least, a lot of dollies giving direct access from sidings to a block section were replaced by semaphores (with short, subsidiary, arms), while these were mainly red there were at least a dozen examples of yellow arms where yellow discs had existed previously. This obviously only happened where there was no advanced starting signal, but it was a lot cheaper to replace a dolly with a semaphore (no changes to the locking being required) than to install a new advanced starting signal (which would have required an extra lever and at least some changes to the locking).

 

Ironically, almost all the locations where the change was made became redundant within a couple of years or so as local goods yards closed.

I doubt if 1959 would be right as signalling design and standards was 100% under Regional control until much later than that and there were definitely new work examples of semaphore ground discs reading into double and single line sections for at least a decade after that.   Similarly the practice with GPLs varied until the 1980s with some Regions using them to read onto running lines for departing trains much later than even then.   So as far as 1959 was concerned it would have been a Southern Region decision (and might even have been restricted to only one of the Region's signalling design offices because they were still doing things a bit differently from each other into the '60s).

[bécasse]

8 hours ago, The Stationmaster said:

I doubt if 1959 would be right as signalling design and standards was 100% under Regional control until much later than that and there were definitely new work examples of semaphore ground discs reading into double and single line sections for at least a decade after that.   Similarly the practice with GPLs varied until the 1980s with some Regions using them to read onto running lines for departing trains much later than even then.   So as far as 1959 was concerned it would have been a Southern Region decision (and might even have been restricted to only one of the Region's signalling design offices because they were still doing things a bit differently from each other into the '60s).

It was definitely circa 1959 (might have been 1960 but no later) and so much work was done - if there were a dozen new yellow signals, there have to have been several score red ones - that it must have resulted from a diktat, there just wasn't enough money floating around for it to have been a "new Chief's whim". I agree that BRB diktats on signalling generally don't seem to have been taken on board by the Southern before about 1965/6 (and some, AWS for example, were resisted for far longer) although the 1959 Kent Coast resignalling did see position light subs rather than motorised floodlit discs (which were still being installed by LT so it wasn't a supply issue). Perhaps, it resulted from an Inspecting Officer's "recommendation" after an incident somewhere, although the use of dollies as section signals (where appropriate) went back to LSWR days.

[Railfreight1998]

Thanks for the input everyone. I'll amend the plan with the yellow disc, and I'll add the down starter as well.