Signalling for Begbrooke - any comments please?

[The Great Bear]

Here's the signal diagram for Begbrooke, the mainline station on my layout under construction:

 

 

 

The layout is GWR 1940s, largely based on Kidlington on the Oxford-Banbury line which was the junction for the Woodstock branch. On my layout it's the junction for Marlingford, my existing branch line terminus.

 

The SRS plan for the prototype can be found here though squinting is necessary. I have the full version of the this and so most of the signalling has been taken straight from this and is hopefully then ok.

 

Where my layout differs from the protype is at the far end of the branch siding where due to space contraints the connection to the mainline has been moved before the farm bridge (as it was inded in the prototype originally) and a double slip used to save space. This is the bit where I have doubt as to what I've done, again I've tried to follow as much of the original as possible. I am not sure to what extent routes in this area each need to be fully signalled to/from the siding.

 

I have had some discussion on how to control the signals and points and interlock the two here

 

Any comments or suggestions would be much appreciated as always. If anything's unclear please don't hesitate to ask.

 

Many thanks

 

Jon

Edited August 23, 2013 by The Great Bear

[The Great Bear]

By the way, I have been considering having a level crossing to the left of the station. I have moved away from that idea, for now at least, and have it off-scene which then allows me to get two distants for it in on scene in same locations as protoype. (Why are there two of them?)

 

Also for now I've shown the distants for this box, again they'll be off scene but I am currently minded to include the levers for them anyway, may be link in some way with fiddle yard operation.

[Miss Prism]

Seems unusual, although not unreasonable (depending on locking complexity), for FPL levers 13 and 23 to be 'shared' between their turnouts?

 

Also unusual is having four levers for each of the two double-slip crossovers (17/20/21/22, and 30/33/34/36). Why not just two levers each?

 

Does the branch need an outer home, instead of 43?

Edited August 23, 2013 by Miss Prism

[The Great Bear]

Thanks, Miss P

 

Seems unusual, although not unreasonable (depending on locking complexity), for FPL levers 13 and 23 to be 'shared' between their turnouts?

Yes, that bit I've taken straight from the real plan.

 

Also unusual is having four levers for each of the two double-slip crossovers (17/20/21/22, and 30/33/34/36). Why not just two levers each?

Now, this is something I am not sure on. For the one by the station I think that is needed to allow full range of movements from down main to down branch, down main to bay/goods yard, up branch to up main and then chuck in for good measure backing move from down main to up main. In similar vein, for the end of the down siding I have allowed I think for full range of options of moves so goods train on mainline could reverse into siding to place/collect wagons from the branch if too long to make a forward move. Or have I got my levers to do this messed up?

 

Does the branch need an outer home, instead of 43?

Good spot! I deleted that from the prototype to save a lever (along with the 4 no. spares: levers I'm going to use like my branch, £14 for one that does nothing is a bit too profligate). Is it necessary? If I allowed a shunting move in the branch siding to use part of the branch (hidden on the layout) I suppose it is?

 

Once again, thanks

 

Jon

 

 

[Edited to put more detail on envisaged moves at end of down siding]

Edited August 23, 2013 by The Great Bear

[The Stationmaster]

Interesting Jon, verrry interesting.  There are certainly one or two oddities in the original at Kidlington (unless the SRS diagram is wrong - well mistakes do happen)  and MissP has picked up the one concerning the double slips where you have replicated in you numbers 20 & 21 = the oddity in No.s 26 & 27 in the original - the only reason I can think for it was something to do with the locking (the answer may lie on the lever leads if they are on the SRS disc by now);  I would think it would be pointless (sorry) replicating it on the model to be honest as you don't face the same safety considerations.

 

You have however needlessly continued the idea to your 34/36 crossover - the correct arrangement here would be one lever for the Branch to Down Main crossover, a second for the slip connection, and a third for the branch siding connection, i.e. your lever 36 is not needed.  The signals there are not too bad but following on from Miss P's point about the provision of an Outer Home (which would then become the Home Signal in GWR terminology) you have put yourself in a position where a train cannot leave Marlingford if the section of line which serves as a Down Loop is occupied or a train is signalled into it.  Therefore you need an additional Home Signal =440yards in rear of No. 42 to give you the flexibility I'm sure you need.  Consider also the sighting of No.42 as I reckon it would most likely be in rear of the overbridge and not in advance of it as you have it at present.

 

I would also tend in the real world to consider a semaphore instead of a ground disc at No.29 but I think it would make the model scene look too crowded and would instead assume - for the period you are modelling - Advanced Starting Signal on both the Main and Branch in advance of the overbridge.

 

BTW the FPL arrangement for your No.13 was not all that unusual, even if they could be 'awkward' to adjust, and probably reflect a single shared locking bar in the original.

 

The two distants on the original would have been there for braking distance - that would require the distant to be out as far as your No.44 which automatically means it woudl also have to be provided below your No.40.

 

Hope this lot helps.

[beast66606]

The two distants on the original would have been there for braking distance - that would require the distant to be out as far as your No.44 which automatically means it woudl also have to be provided below your No.40.

 

Off topic

 

For interesting distant working see Wrexham when all the boxes were open, some of the distants (on the up) had 5 (iirc) slots on them - must have been very nice to watch the signals clearing for the "Paddy" as all the homes cleared from North to South and then the distants cleared, but in the reverse order..

[The Great Bear]

Hope this lot helps.

Yes it does - a lot, as usual. Thank you, Mike. A fuller response, likely with some follow up questions some time later. The signals themselves I'm not going to add for ages - don't want to damage them, several accidents with the branch ones learnt that lesson - main reason for doing the diagram now:

• Before I place scenery e.g. No.42 move bridge not signal(!), I'm pretty set on idea of this one being "on-scene"
• To inform discussion on how I'm going to do this technically especially interlocking (see related thread) - currently looking promising in this regard; fingers crossed the bit of kit I'd bought in haste will actually do the job, though will need at least one more of them based on number of lever's I'll have and 
• I need to find space for the lever frame - the DCC concepts levers suit me, look good enough for my purposes, and easy to use, but are a bit large. A 50 lever frame is going to be best part of a metre long!

 

Once again thanks and trust you had a good holiday. I see your interest in signals is not limited to just railway ones;)

 

All the best

 

Jon

Edited August 23, 2013 by The Great Bear

[beast66606]

One comment on the plan.

 

If the distant is slotted by Rowel Lane Crossing there should (I think) also be a Rowel Lane home with an inner distant worked by the box.

 

In case you don't know, convention does not colour signals controlled by other boxes.

[Miss Prism]

Concerning the slip crossovers, I can't see any movement for either of them that wouldn't be covered by two levers (FPLs omitted for clarity), and fewer levers always seems to be a good objective *:

 

 

What route does 7 signify?

 

Is there an arm below 41?

 

On the branch home issue, sorry, I hadn't spotted your 42, so maybe your 43 can be just a fixed distant.

 

 

* ISTR some arrangements for mainline double junction crossovers (Goring?) given in Adrian Vaughan's The Heart of the Great Western display separate levers for some of the crossovers, so maybe there is some method in the madness.

Edited August 23, 2013 by Miss Prism

[beast66606]

7 is to the branch siding

 

Sometimes the levers are simply too "heavy" with all the blades on them (normally when they are far away), so they become single ended.

[Miss Prism]

7 is to the branch siding

Is 7 therefore necessary given 24? (Interesting comparison with Bucks Hill).

 

Sometimes the levers are simply too "heavy" with all the blades on them (normally when they are far away), so they become single ended.

Unlikely to be the case with Begbrooke (or Kidlington for that matter).

[HAB]

The GW seemed often to use three levers in this double slip situation - here is an extract from Exeter West to illustrate

 

 

 

You can see that both sets of switches at the same end of the slip are worked by separate levers, but one set of diagonally opposite switches are worked by the same levers (53A/B and 54A/B in this case). In this case, the other switches work as one end of a crossover. (ie 52A/B and 43A/B)

 

This frame at Exeter West was installed around 1960 (and is extremely well laid out BTW!)

 

 

 

Cheers,

[The Great Bear]

Thanks, again.

 

Is there an arm below 41?

 

 

The arm below 41 (No.37) is calling on arm. Discussed in here Whether or not I actually include this not sure, but it's a slightly unusual feature I think so maybe yes.

 

Still head scratching on the crossover/slips. Finding hard to visualise; need to go out to the shed and figure it out!

[The Great Bear]

7 is to the branch siding

Thanks. I'm nervous to question someone with your knowledge, given how limited mine is but my interpretation of SRS plan is that 7 was for the branch, 4 for to the down main with ground disc 24 for entry to the branch siding. Would that make sense? Must admit the bracket arrangement then seems wrong way around, as surely the branch is the main route? Think what I've shown is how it appears in photos.

[beast66606]

Is 7 therefore necessary given 24? (Interesting comparison with Bucks Hill).

 

 

Unlikely to be the case with Begbrooke (or Kidlington for that matter).

 

1 - 24 is an in route disc - not that uncommon

 

2 - How can you judge that ?

[beast66606]

Thanks. I'm nervous to question someone with your knowledge, given how limited mine is but my interpretation of SRS plan is that 7 was for the branch, 4 for to the down main with ground disc 24 for entry to the branch siding. Would that make sense? Must admit the bracket arrangement then seems wrong way around, as surely the branch is the main route? Think what I've shown is how it appears in photos.

 

Signal 6/8 is the routing signal

[The Stationmaster]

Thanks. I'm nervous to question someone with your knowledge, given how limited mine is but my interpretation of SRS plan is that 7 was for the branch, 4 for to the down main with ground disc 24 for entry to the branch siding. Would that make sense? Must admit the bracket arrangement then seems wrong way around, as surely the branch is the main route? Think what I've shown is how it appears in photos.

 

I suspect that was very probably the case Jon (although the lever leads would let us know definitely if they should come to light at some time).  The problem is that what appear to modern eyes to be leading discs (noted by Beast as an 'in route disc') are probably nothing of the kind but are most likely 'white light discs' which could be passed in the 'on' position when the points at which they applied were standing normal  (and should not be confused with the yellow arm disc signal - it wasn't used by the GWR and in any case wouldn't be correct in the position of No.s 12 & 24 on the Begbrooke diagram in the OP) - 12 & 24 could only be cleared with the relevant points standing reverse and as such would only be used in conjunction with shunting movements.  No.s 15 & 16 would also be white light discs.

 

I'm afraid that the Exeter West example has injected some confusion into the situation regarding slip numbering as it is immediately clear that 52 works as a crossover  which means 57 would inevitably be a separate lever - slightly different from the situation at Begbrooke (and Kidlington) where 26 and 27 exist as separate levers it what would normally be a crossover situation from Down Main to Up&Down Branch (aka Down Loop) although as explained below there is still a need to lock out conflicts on parallel routes in the double slip.  

 

 

As I stated above I suspect these two were separated at Kidlington for safety/interlocking reasons - and that situation needn't apply on a model railway.  Miss Prism has drawn an excellent little diagram of the usual way of arranging the working of a single slip involving a pair of crossovers - where lever C would work the slip connection between the two crossovers but the diagram also illustrates the potential conflict as A& B need to be reversed to allow a movement from =Branch Siding to Main whereas they should not be capable of being reversed at the same time as that would create a conflicting situation.  By separating the lever which creates the potential conflict (e.g. No 34 at Begbrooke) it becomes possible to easily lock the two potentially conflicting routes against each other.  Whether this is necessary at Begbrooke is really for Jon to judge as the model doesn't necessarily require anything like the same level of flank/conflict protection as the real thing (does it?).  And incidentally there is an example at Didcot East End  where there is a whole ladder of slips connections numbered in the way explained by Miss P's drawing.

 

PS And I keep forgetting to add that the Branch Distant (No.43) would be fixed at caution, another lever saved!

 

Edited August 23, 2013 by The Stationmaster

[Miss Prism]

1 - 24 is an in route disc - not that uncommon

 

Fair enough.

 

2 - How can you judge that ?

 

I'm guessing the distance between Begbrooke's box and the slip crossovers isn't too far! That doesn't in itself explain the Kidlington arrangement though, which is also reasonably close to the box, so is not a distance issue either. Howard's two double slips arrangement at Exeter West is perhaps overcomplicated, and I can't immediately see its application to a single double slip situation, which is what we have in Begbrooke.

 

Jon - thanks for the signal 24 thread link. (My mistake for not spotting the 37 annotation on your plan.)

 

[The Great Bear]

I suspect that was very probably the case Jon (although the lever leads would let us know definitely if they should come to light at some time).  The problem is that what appear to modern eyes to be leading discs (noted by Beast as an 'in route disc') are probably nothing of the kind but are most likely 'white light discs' which could be passed in the 'on' position when the points at which they applied were standing normal  (and should not be confused with the yellow arm disc signal - it wasn't used by the GWR and in any case wouldn't be correct in the position of No.s 12 & 24 on the Begbrooke diagram in the OP) - 12 & 24 could only be cleared with the relevant points standing reverse and as such would only be used in conjunction with shunting movements.  No.s 15 & 16 would also be white light discs.

Possibly a silly question: "White light disc", does that do exactly what it says on the tin: a normal ground disc but with different coloured spectacle glass (which one does the white replace?)

 

Possibly an even more silly question: does the same apply then to signals lets say on an engine release crossover or in case or Marlingford if I hadn't chickened out on fully signalling it the signal from the loop back to the branch, because it needs to passes if on to get to the cattle dock.

[HAB]

 Howard's two double slips arrangement at Exeter West is perhaps overcomplicated, and I can't immediately see its application to a single double slip situation, which is what we have in Begbrooke.

 

 

Well, over complicated it might indeed be, but it was how the GW did it! (even though the Southern never did it that way, and the LNW would have used 6 levers for the two crossovers and had no shunting signals at all)

 

Here is what it would look like...

 

 

Of course, just because that is how the Real Thing might have done it is no reason to do it that way on the model - (depending on how the track is to be built - if it is Peco, it can't be done that way!!!)

 

Hope that is a bit clearer!

 

Cheers,

Edited August 23, 2013 by HAB

[Miss Prism]

By separating the lever which creates the potential conflict (e.g. No 34 at Begbrooke) it becomes possible to easily lock the two potentially conflicting routes against each other.

 

 

It would be an interesting exercise to compare the locking arrangements for the different approaches to see if one was indeed 'easier' than the other, but I still can't help thinking the extra levers and rods does seem an excessive and potentially less safe solution compared to a more conventional arrangement. Maybe Kidlington box was born in an era where the number of lever pulls took precedence over 'good practice'.

 

Btw, the Goring analogy may not have been a fair one, as I suspect the rod and (generous) switch lengths had a bearing on the matter, and of course slips were not involved, the main diamonds being switched, so had their own rods.

 

Edit: having seen Howard's latest diagram (post #20), that makes more sense, but doesn't the dual purpose FPL 33 mean that just as many lever pulls are involved in any crossing movement? (And I note it would involve segregating the stretcher bars at each end of the slip, which was most unusual on the GWR.)

Edited August 23, 2013 by Miss Prism

[The Great Bear]

Of course, just because that is how the Real Thing might have done it is no reason to do it that way on the model - (depending on how the track is to be built - if it is Peco, it can't be done that way!!!)

FWIW the points are indeed Peco and down already

[The Stationmaster]

It would be an interesting exercise to compare the locking arrangements for the different approaches to see if one was indeed 'easier' than the other, but I still can't help thinking the extra levers and rods does seem an excessive and potentially less safe solution compared to a more conventional arrangement. Maybe Kidlington box was born in an era where the number of lever pulls took precedence over 'good practice'.

 

Btw, the Goring analogy may not have been a fair one, as I suspect the rod and (generous) switch lengths had a bearing on the matter, and of course slips were not involved, the main diamonds being switched, so had their own rods.

 

Edit: having seen Howard's latest diagram (post #20), that makes more sense, but doesn't the dual purpose FPL 33 mean that just as many lever pulls are involved in any crossing movement? (And I note it would involve splitting the stretcher bars at each end of the slip, which was most unusual, particularly for the GWR.)

Did you miss out a word there Miss P - in my experience - albeit far from exhaustive - I can thing of very, very few mechanically worked double slips on the Western where both sets of switches at any end were worked by the same lever although I know there were some examples? (Have a look at the ladder in the middle siding at Didcot East End)

 

As far as Begbrooke at the branch junction is  concerned what they would have been seeking to avoid was setting a conflicting route through the Mains trailing crossover (No.17) at the same time as a route was set through the Down Main to Up & Down Branch crossover (No.s 20 & 21) but also having to cater for a route from the Branch to the Up Main which would therefore require 17 reverse at the same time as the other crossover.  By splitting the two ends 20 & 21 it was possible to lock out such a conflict within the point levers and without any conditional locking because the Mains crossover lever 17 would lock 20 & vice versa) but would not lock 21.  And most likely 22 would be released by 17 AND 21 (and would probably also lock 20, & vice versa).  By this means virtually all potential conflicts would be locked solely by the point levers which would have the overall effect of potentially reducing some other locking.  This in turn suggests to me that Kidlington had an early design of frame with either Stud or Twist locking and it certainly has some features of relatively dated GWR signalling practice - probably no later than the early 1920s I would think.

 

The purpose of this type of design, and the alternative shown in Howard's sketch, was not necessarily to save lever movements but to provide safe interlocking for whatever was in mind to be done, or to prevent happening, on the layout.  The use of double ended FPLs arranged as No.33 is in that sketch is I think more unusual although I know of instances where it was used - with all its attendant problems in some BR era designs (the problems are both technical - the things are a devil to get set-up - and operational as having one FPL lever out of action for whatever reasons lands you with twice as many potentials for derailment and need for point clipping & handsignalling especially if the points involved need to be swung frequently; I have the relevant Tee-shirt alas).

 

You are correct of course regarding the Goring analogy but look at Cholsey & Moulsford and Moreton Cutting - several ways of skinning a cat

 

 

 

Possibly a silly question: "White light disc", does that do exactly what it says on the tin: a normal ground disc but with different coloured spectacle glass (which one does the white replace?)

 

Possibly an even more silly question: does the same apply then to signals lets say on an engine release crossover or in case or Marlingford if I hadn't chickened out on fully signalling it the signal from the loop back to the branch, because it needs to passes if on to get to the cattle dock.

I seem to recollect having been here once before but no harm in going through it again, expanded if necessary.  The GWR began introducing 'white' light in ground discs and certain other signals in the 1890s and did so in order to cater for a problem with its then current interlocking designs which did not allow an 'each way' release between levers.  Thus signal levers in respect of points were either released by them or locked them and that meant that shunting signals would inevitably have to be passed at danger for facing movements in one direction or the other at points.  So the Company introduced a 'white' light at signals which needed to be passed at danger when the points were set in their normal position and only gave a green when the signal was cleared with the points set to reverse.  The 'white' was achieved by removing or, later, omitting the red shade so it was actually the light of the oil lamp through plain glass.

 

But the principle was always that there would be a red somewhere in advance of the movement in order to provide a final and definite stopping point.  This at Begbrooke 16 would havea  white light and would not be cleared for a move towards 28 but 28 would have a red light to stop any further movement in the wrong direction.  But 31 might well have a red in order to protect against conflicting moves in the double slip.  Backing Signals also had white lights aithough by the 1930s some had red lights but some with white lights definitely survived into the 1960s; similarly Siding Signals and some Goods Loop Line Signals had white lights but that was being superseded by red in many signals by the 1930s.

 

The important thing to remember in all of this is that the colours of lights in signals didn't necessarily mean what we assume it to mean nowadays - white was originally a danger signal so a shunting disc etc with a white light still remained exhibiting a danger light but it was one which could be passed on the authority of a Shunter; red could only be passed on the authority of the Signalman.  Green incidentally meant 'caution' and it remains to this day the colour for 'slow' in shunting handsignals (while, just to confuse things, white is the colour for 'normal shunting speed' in handsignals).  Thus if a Fireman or Secondman etc observing the Shunter's handsignals from the other side of an engine shouted 'green light' to the Driver while shunting it meant, and still means, 'slow down'.

And you thought foreign languages were difficult?  Good old 'railway English' lived in a world of its own but at least we all understood it.

[HAB]

FWIW the points are indeed Peco and down already

 

Then the answer is clear and the discussion academic - but no less interesting for that

 

Good luck and looking forward to seeing the result!

 

Best wishes,

[The Great Bear]

This in turn suggests to me that Kidlington had an early design of frame with either Stud or Twist locking and it certainly has some features of relatively dated GWR signalling practice - probably no later than the early 1920s I would think.

Correct Box was 1890s vintage, I think.

 

I seem to recollect having been here once before but no harm in going through it again, expanded if necessary.

Now that you mention it, I do recall that thread.