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Lacathedrale

Can I have some help Signalling (and interlocking) a pre-group urban terminus, please?

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Here's the track diagram, set in ex-SER/LCDR territory pre-1913 (hence red distant signal at 24, and ringed shunt-ahead signals on the platforms):

 

image.png.ed3014e039e5ea1b4334df4a050d0ba9.png

 

A few small notes:

  • x and y represent a train length distance, as well as the boundary of the main layout. From 'x' to 'down' (and 'y' to 'up') is on a separate optional board.
  • the blue section, levers and signal is the next signal box block, after which there is an immediate exit to a FY.
    • It is neccesary to support moves from the Down line, over the crossover and towards Y (but not the home signal) to shunt the FY - hence the placement of this box's home signal and the use of a second block.
    • For this diagram/signalling solution, I have not included any interlocking for turnouts A and B forming that crossover, or ground signals C/D, or that box's Advanced Starter
  • lever 24 represents a distant signal for this box
  • the group of six levers 18-23 is the home signals for this box - there is no direct access to platform 1 from the up main, so it is omitted.

 

Here is my understanding of how the interlocking would work - there are a number of implicit locks, for example Lever 1 platform starter being pulled off, is only contingent on lever 10 being off already - but lever 10 is contingent on lever 11 being off, and so on.

 

image.png.dc389de9815a6d3c058ae64d6e4d8dc5.png

 

Summary:

  • Each turnout is locked by specific requirements and geometry (i.e. for 12 to be closed, 13 must be closed also)
  • The Distant is unlocked to pull off by available platform route indicated by home 18, 20 or 22
  • Each Home arm is locked by outbound starter/shunt signals from the relevant platform
  • Each platform starter is mutually exclusive with all other platform signals, since the next signal is the following boxe's home signal
  • Each platfom shunt ahead signal is exclusive with its own starter

 

I would really appreciate any thoughts or comments on this one!

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Posted (edited)

Do you not need some kind of advanced starter? Otherwise you've got no way to shunt stock into P1 or in/out of the shed without going into the block section (I don't know if that would be accepted practice then?). You'll also need some kind of signalling to allow locos to back onto the stock from the down line. I'm not sure you'd need the calling on signals on the homes though, unless you've got permissive platforms (more than one train in the platform), I think all shunt moves would use the down line rather than the up - but I might be wrong there.

 

I'd expect the crossovers to the worked as pairs - so 12/14 would be on one lever, as would 13 and the platform end of the double slip, and 17/10

 

Platform starters and inner homes would be locked by the points, so don't need to be locked against each other.

 

So here's my take - assuming up->p2 xover are both on 14, 12 becomes advance starter and 19 moves across to be "shunt up from points 11" - I think the SE companies just used a single shunt signal for multiple routes, like the SW and Brighton did.

 

N is normal, R reverse, B both (i.e. the signal locks the points whichever way they are set). Normal for signals is 'on', and I've assumed normal for points is up->p3, p2->down, and #10 set for p1.

 

1 (p1 starter): 10N 11R 5N 19N

2 (p2 starter): 14N 13N 11N 6N 19N

3 (p3 starter): 13R 15N 21N 7N 22N (last preventing a move into P2 crossing the one going out of P3)

4 (p4 starter): 13R 15R 21N 8N 22N

5 (p1 shunt): 10N 11R 1N 19N

6 (p2 shunt): 14N 13N 11N 2N 19N

7 (p3 shunt): 13R 15N 21N 3N 22N 19N

8 (p4 shunt): 13R 15R 21N 4N 22N 19N

9 (shed exit shunt): 17R 10R 11R 19N

10 (shed points): 11R

11 (p1 points): none

12 (advance starter): none (slotted by box in advance)

13 (p3/4 to down main crossover): none

14 (up main to p2 crossover): none

15 (p4 points): none

16: spare

17: spare

18 (p4 home): 14N 15R 4N 8N

19 (shunt up at points 11): 11B 13B 15B 1N 2N 3N 4N 5N 6N 7N 8N 9N

20 (p3 home): 14N 13N 15N 3N 7N

21: spare

22 (p2 home): 14R 2N 6N 3N 4N 7N 8N

23: spare

24 (distant): 18R or 21R or 22R (slotted by box in rear's advance starter)

 

Some of these are redundant as the same thing is required both ways (e.g. all the signals locked by 19, also lock 19 themselves)

 

 

Edited by Nick C
added lever descriptions

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Posted (edited)

The signal arms are all facing the wrong way! :o

 

If no-one beats me to it I might draw up my own interpretation tomorrow, but at a glance I agree with much of what Nick C has said. 

 

Edit:  I haven’t seen any mention of Facing Point Locks. All points used for facing passenger moves need an FPL, usually worked by a separate lever which is interlocked accordingly....

 

..... or you can just assume that Economic FPLs are in use, but I don’t know if the SECR used them. 

 

Edit 2: Nick C’s table has missed some of the reciprocal locking between levers, and “classic” point lever locking, eg 13R would lock 14N and vice versa. That would simplify the locking quite a bit. 

Edited by Titanius Anglesmith

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>>>It is neccesary to support moves from the Down line, over the crossover and towards Y (but not the home signal) to shunt the FY - hence the placement of this box's home signal and the use of a second block.

 

Sorry, but could you explain that more clearly please?

 

If this is a terminus, then should not your Down and Up directions be reversed, or is there some reason for the line apparently being Up to the terminus?

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3 hours ago, RailWest said:

 

If this is a terminus, then should not your Down and Up directions be reversed, or is there some reason for the line apparently being Up to the terminus?

 

The OP’s layout is set in London

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5 minutes ago, Titanius Anglesmith said:

 

The OP’s layout is set in London

Ah...well, (s)he didn't say that :-)

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Attached a drawing of the signalling and P Way arrangement at Cannon Street Hull, H&BRly, layout wise there is a vague similarity and the H&BRly was in many ways influenced by the LC&DRly.

8 CANNON STREET.JPG

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5 hours ago, RailWest said:

>>>It is neccesary to support moves from the Down line, over the crossover and towards Y (but not the home signal) to shunt the FY - hence the placement of this box's home signal and the use of a second block.

 

Sorry, but could you explain that more clearly please?

 

The FY are fans of sidings beyond the blue block - so in order to reduce handling, there is an on-layout trailing crossover. It is not neccesary for any movement to actually pass the layout's home signal - but just an explanation of why it's there and not signalled/interlocked. If there we I imagine a bell code 'shunt into forward section' would be sufficient on that odd occasion.

 

@Nick C - I originally sited an Advanced Starter just ahead of the blue signal box's home - is it worth adding back? Reading through your interlocking list now, I'll need to digest - thanks!

 

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50 minutes ago, micknich2003 said:

Attached a drawing of the signalling and P Way arrangement at Cannon Street Hull, H&BRly, layout wise there is a vague similarity and the H&BRly was in many ways influenced by the LC&DRly.

8 CANNON STREET.JPG

 

Thanks for posting that diagram. I have always had a bit of an interest in Cannon St.

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12 minutes ago, Lacathedrale said:

 

The FY are fans of sidings beyond the blue block - so in order to reduce handling, there is an on-layout trailing crossover. It is not neccesary for any movement to actually pass the layout's home signal - but just an explanation of why it's there and not signalled/interlocked. If there we I imagine a bell code 'shunt into forward section' would be sufficient on that odd occasion.

 

@Nick C - I originally sited an Advanced Starter just ahead of the blue signal box's home - is it worth adding back? Reading through your interlocking list now, I'll need to digest - thanks!

 

 

It may not be on the model. But to produce a properly interlocked layout you need to consider all the signals (and turnouts) that would be controlled by the box even if they are off-scene. Otherwise, all the numbering will be wrong.

 

Others have already highlighted serious errors: no FPLs, double-slip with only one lever.

 

I think that usual practice would be for 1 to be the incoming distant with the outbound signals at the other end of the frame.

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33 minutes ago, Joseph_Pestell said:

 

Thanks for posting that diagram. I have always had a bit of an interest in Cannon St.

Joseph, if of interest I have several photo's of Cannon Street.

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10 hours ago, Joseph_Pestell said:

 

I think that usual practice would be for 1 to be the incoming distant with the outbound signals at the other end of the frame.

IMHO that would depend upon where the signal-box is located and which way it faces. I am assuming that the OP has drawn the diagram "as the signalman would see the layout when standing at the frame", in which case the numbering is indeed the right way around.

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1 hour ago, RailWest said:

IMHO that would depend upon where the signal-box is located and which way it faces. I am assuming that the OP has drawn the diagram "as the signalman would see the layout when standing at the frame", in which case the numbering is indeed the right way around.

Agreed - as I understand it frames were usually* numbered from the point of view of the signalman standing facing the frame - so 1 would be the first signal reached by a train travelling left-to-right, and the highest number the first signal reached by a train travelling right-to-left.

 

Looking through old diagrams can throw up some confusion when stations are resignalled, especially if the box moves to the other side of the track, or a frame is fitted facing the other way - in either case the whole diagram is flipped and all the numbers changed!

 

*I bet there's an exception somewhere...

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Reworking the signalling based on the advice so far - so just to be clear, there should be an Advanced Starter between X and the blue 'home' signal? Presumably there should be at least one train length between it and the blue home signal? In my case, I don't have that space - there is approx one train length between point 11 (on my diagram) and the blue home.

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1 minute ago, Lacathedrale said:

Reworking the signalling based on the advice so far - so just to be clear, there should be an Advanced Starter between X and the blue 'home' signal? Presumably there should be at least one train length between it and the blue home signal? In my case, I don't have that space - there is approx one train length between point 11 (on my diagram) and the blue home.

That's the challenge of model compression! You need enough space between points 11 and the advance starter for the longest train you're going to want to shunt to P1. I'm not an expert on very short sections, but I think the practice would be that one signal would form both roles, starter for black and home for blue, with the signal being 'slotted' so that it requires both signalmen to pull it before it would clear.

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There is definitely enough space between points 11 and the advanced starter, but there's also not enough space for advanced starter to home  too - but if I can get away with a slotted advanced starter/home with some 'special instructions' to cover that idiosyncrasy, that seems like a happy compromise.

 

You mentioned that the slips/crossovers would be worked by one lever, but  @Joseph_Pestell has stated the opposite - which one is it? :)

 

I assume the down main  (as per my diagram) will be used for all shunting as you have said, @Nick C

 

If we sidestep the intricacies of the interlocking and numbering (everyone's comments on which I'm very thankful for and still trying to grasp - clearly there is more studying to be done) - do the signals now work?

 

image.png.c2a43a969801908972e67966c782b51c.png

 

I have:

  • Tidied up the right hand side:
    • Added the slotted advanced starter/home (numbered 25 for reference)
    • Added representations of the ground signals controlled by bridge box (ref C and D) for crossover A + B
    • Added representation of the starter for the bridge box (ref F)
  • Removed the call-ahead signals on the home, since this will be covered by shunt ahead signals from the platform roads and the Up main won't be shunted

 

 

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13 minutes ago, Lacathedrale said:

You mentioned that the slips/crossovers would be worked by one lever, but  @Joseph_Pestell has stated the opposite - which one is it? :)

 

Each crossover would be worked by one lever, because you always want both ends set the same way (either both for the main, or both set to cross). You can't work both ends of a slip from one lever though - think of a double slip as really being two separate points toe-to-toe - one half of it is, in your case, the end of the crossover, and the other half is the points controlling access to P4.

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I’d add a shunt disc at the toe of 11 points reading towards the platforms. Alternatively these moves could be made by hand signal from the signal box which is likely close by. 

 

I don’t think you need the shunt arms on the starters now as the advanced starter will limit all moves from the platforms. 

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Yep, you need the shunt signal at 11 to allow moves back into the station.

 

I'd also be tempted to make #24 into an outer home rather than a distant - slotted again in the same way as the starter. It's going to be way too close to be a distant, as it's only just over a train length away - the distant would be about half a mile away (full braking distance from the first stop signal)

Edited by Nick C

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3 hours ago, Nick C said:

Agreed - as I understand it frames were usually* numbered from the point of view of the signalman standing facing the frame - so 1 would be the first signal reached by a train travelling left-to-right, and the highest number the first signal reached by a train travelling right-to-left.

 

Looking through old diagrams can throw up some confusion when stations are resignalled, especially if the box moves to the other side of the track, or a frame is fitted facing the other way - in either case the whole diagram is flipped and all the numbers changed!

 

*I bet there's an exception somewhere...

Well, yes and no.

 

Although *generally* the first signal going from L to R would be the distant and therefore lever 1, it was not unknown for various reasons for the main running signals to start at a higher number (in some later frames the Up and Down signals were together in the middle of the frame). It was common also in later years to find frames where, after the distants had been converted to 'fixed' arms, then their levers were re-used for other purposes which might be at the other end of the layout!

 

I recall hearing of one location (somewhere at Euston????) where a very long frame at the front of the box was replaced by an equally long one at the rear of the box, but simply as a like-for-like renewal for a worn-out frame rather than for layout alterations. To save the signalmen having to learn a whole new set of numbers, the new frame was numbered identically but from R to L. Can anyone add any more please???

 

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The "Reverse Numbered" frame was on the LNWRly, from memory, it is mentioned in Richard Foster's book on LNWRly signalling.

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Shunt signal at 11 included, thank you - that's really the crucial aspect of this discussion and I do appreciate it. Thank you for the advice that the ringed shunt-ahead signals would not be required, but they are such an iconic part of the Charing Cross/Holborn Viaduct stations I'm modelling I feel that they are a neccesary inclusion even if not strictly neccessary. I'll need to include FPL covers on basically all my turnouts apart from 17?

 

If I change the distant to an outer home, it puts crossover A-B into the remit of my signalbox -but I feel that this crossover must work independently of the station. In that case, distance X/Y should definitely suit an outer home, but operationally may better be represented by an advanced starter/distant?

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As a big fan of your ringed "shunt ahead" signals, and having tried in the other thread to discern exactly what they meant at Charing Cross, I'm afraid that I concur with titanius that they are probably unnecessary here.

 

At C+, from what I could work, out they were needed because the 'engine moves' were not allowed to go all the way to the next stop signal, just short of Waterloo, but only as far as clear of crossovers giving access to an engine layby, or direct into that layby.

 

But, if I were you, I would keep them, impose a limit on engine moves just clear of 11 points, and assume that was far enough in rear of 25 to allow a ringed arm to be cleared as soon as a train's tail-lamp was beyond 25.

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1 hour ago, Nearholmer said:

As a big fan of your ringed "shunt ahead" signals, and having tried in the other thread to discern exactly what they meant at Charing Cross, I'm afraid that I concur with titanius that they are probably unnecessary here.

 

At C+, from what I could work, out they were needed because the 'engine moves' were not allowed to go all the way to the next stop signal, just short of Waterloo, but only as far as clear of crossovers giving access to an engine layby, or direct into that layby.

 

But, if I were you, I would keep them, impose a limit on engine moves just clear of 11 points, and assume that was far enough in rear of 25 to allow a ringed arm to be cleared as soon as a train's tail-lamp was beyond 25.

But are they needed or not.  it surely depends on the signal practice of the original (i.e that being modelled) company.  It would appear to me thjat the subsidiary arms coule d vbe worked in either of two ways, viz -

1. They would be used to signal a shunting movement, for whatever reason in the same line of route as the running signal as well as movements to lines not in the route signalled by the running signal,  or

2. They would nl;y be used to signal s movement to a line not in the route signalled by the running signal.

 

Their use in the first case could of course possibly depend on the extent of movements made into an occupied signal section but equally it could be the practice of the company to provide such a subsidiary for any shunting movement irrespective of line occupation.  So whatever other signal there might be in advance of the platform starting signals  may not have any relevance at all to the provision, or non-provision, of the subsidiary arms.  A couple of early SER examples seem to indicate - because there is no alternative - that such subsidiaries did (=could) read in line of route of the running arm but I am hardly an expert on SER/LC&DR signalling practice 

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