Single-Lever Crossover suitability? (Victorian/Edwardian period)

[Lacathedrale]

It occurs to me on my layout, while musing about signalling at the office, that there seem to be three pairs of turnouts which always need to actuate at the same time, those marked 2, 4, 5 and 9 below:

 

 

It seems than rather interlocking where the first lever unlocks the second lever which then locks the first - they could simply be keyed off the same lever?  Number 9 is a local ground frame, unlocked by signal box Lever 12

 

Are there any other pairs I've missed, or obvious muck-ups?

 

I'm not worrying about interlocking or signalling at this point, but it's indicated on this plan courtesy of @Regularity and more generally on the horizon while I think about levers, frames, microswitches, etc.

 

Incidentally my assumption for the default position of the turnouts is that Down Main runs to P2, and P1 to Up Main, and Loop into Turntable road.

 

 

 

 

[Michael Hodgson]

 

At first sight this looked great, but the main issue I have with this layout is I would expect all shunting from the platforms/yard to be done onto the Up rather than the Down line.  If you were to shunt onto the down main even though you have an outer home you'd  still need to block back and you wouldn't be able to accept arriving trains, which is operationally very inconvenient.

 

The pairing looks correct for the normal lie as stated, although 7 and 1 also have to operate together.  However I think the normal lie of the Down would much more likely be into Platform 3 rather than 2, and of course altering the normal lie affects how the points pairing would work.

 

 

You would need a shunt signal from the loop/CS to the Up Main and probably also to the turntable road.  I don't think you'd need a running signal as trains wouldn't depart from there, although perhaps a light engine might.  Unusual for a station not to have goods facilities, but they could be elsewhere, off-scene.

 

You have two possible arrival routes into platform 2: via 5 Normal or vis 8 Reverse, so which way does your signal read?  The latter is the straight route, but it cannot be used while a train is departing from platform 1, and therefore I would expect the locking to force you to use former.  If the latter were also required, there would need to be additional locking and I think that means an extra lever.

 

In practice I doubt there would be provision for arrival into Platform 1 (which requires 1 and 7 reverse).  I would expect practice in this era to be to shunt departure stock to that platform as required and since all shunting would be done using the Up road, there would be no regular movements requiring the 1/7 crossover either, so I don't think they would be provided (on cost grounds) - meaning your single slip isn't there !  I also think it would be unlikely to want a train to arrive into the Loop/carriage siding - it would arrive in a platform and be shunted there, so no need for a running signal into it.

Edited February 15 by Michael Hodgson

[Jeremy Cumberland]

5 on the down main needs to work with 6 on the slip (not necessarily on the same lever). 5 on the slip is independent (and could even be hand-worked (but not if you are giving the loop and carriage siding separate exit signals).

 

10 and 11 work together, probably on one lever.

[Lacathedrale]

@Michael Hodgson I too am expecitng to use the up main for shunting - the notes and signalling on this plan are a great first draft but do not reflect the 'current' status - which is why I'm mainly focusing on the levers. I did mention in my OP "I'm not worrying about interlocking or signalling at this point," 

 

The period I'm aiming for is 1911 - I just wanted to clarify the potential difficulties and cost-savings that might be at play. Particularly the length of rodding runs. This is a secondary terminus after all! Setting aside the signalling just for a bit, since that's got a lot more rigour to go through, to talk through your points:

• 7 and 1 - Is it simply a factor of the normal lie, that  7 being set to reverse must require 1 to be reversed also?
• It's not clear to me why the normal lie of the Down would be much more likely to go into Platform 3? I am very much standing on the shoulder of giants here,.
• Arrivals to P2 - as you have surmised, definitely through 5 normal - the crossover formed by 4 and 8 is for P2 departure, which blocks the fewest other platform roads.
• Arrivals into P1 - I like the idea of Arrivals into P1 being relatively rare, but I'm not about to start pulling up the track at this point :)

 

@Jeremy Cumberland can you please clarify about 6 and 5? I can't see why they need to work together and it seems your second sentence contravenes your first?

 

Would the trap point for 11 really work on the same lever as the actual point on 10? I'm happy to save some space and locking!

[Jeremy Cumberland]

6 minutes ago, Lacathedrale said:

@Jeremy Cumberland can you please clarify about 6 and 5? I can't see why they need to work together and it seems your second sentence contravenes your first?

The crossover to the loop and carriage sidings goes from 5 on the down main to the left hand switches of the slip, not to the right hand switches of the slip. The right hand switches determine whether trains go to/from the carriage siding or the loop, and since both of these are separate from the running lines, they could be hand worked (although this is a bit unlikely in what appears to be a busy location, and it is not compatible with having separate signals for the two lines).

 

This crossover needs to work together since 6 acts as the trap for the loop and carriage siding. It needs to be set to the turntable road unless trains are being crossed to or from the running lines, via 5 on the down main.

 

16 minutes ago, Lacathedrale said:

Would the trap point for 11 really work on the same lever as the actual point on 10? I'm happy to save some space and locking!

Absolutely! It is rare for traps to be operated independently. You might have it with the slip, since there are 6 switches, which seems a lot to put on one lever.

[Lacathedrale]

I'm sorry, I'm getting muddled up trying to figure this one out. I've re-written this reply a few times trying to puzzle what the implications are :( Do you mean right hand while approaching from direction of travel, or right hand from the plan's birds eye view?

[Michael Hodgson]

52 minutes ago, Lacathedrale said:

@Michael Hodgson

 

• 7 and 1 - Is it simply a factor of the normal lie, that  7 being set to reverse must require 1 to be reversed also?
• It's not clear to me why the normal lie of the Down would be much more likely to go into Platform 3? I am very much standing on the shoulder of giants here,.
• Arrivals to P2 - as you have surmised, definitely through 5 normal - the crossover formed by 4 and 8 is for P2 departure, which blocks the fewest other platform roads.
• Arrivals into P1 - I like the idea of Arrivals into P1 being relatively rare, but I'm not about to start pulling up the track at this point :)

 

@Jeremy Cumberland can you please clarify about 6 and 5? I can't see why they need to work together and it seems your second sentence contravenes your first?

 

Would the trap point for 11 really work on the same lever as the actual point on 10? I'm happy to save some space and locking!

 

7 and 1 - Is it simply a factor of the normal lie, that  7 being set to reverse must require 1 to be reversed also?    Sort of - 7 is reverse only when 1 is, and 1 is reverse only when 7 is.  So you might as well save the cost of a lever.  However that would be different if there were flank prtoection or trapping reasons to have only one of them reverse,  but I don't see an issue here.

 

 

I think the reverse curve arriving into 2 road means the route into 3 is cleaner, so it would seem a better default.  It's true that the alternative route into platform 2 would address that even better, but keeping 1 and 7 points normal does avoid the risk of a head-on if a train departed from 1 irregularly while something is entering 2 road.

 

Arrivals into P1 - given that the track is as it is, I think they would have provided the signal into that platform - it's the only reason I can see for have those points!  Some stations did have signals which hardly ever get used.  Might be justified if three trains arrived in quick succession - perhaps seaside specials if it is a seaside resort.

 

I agree that 5 and 6 do not work together, but you've got the numbers transposed on the diagram as 5 works three sets of switch blades, two of them on the double slip.  5 normal, gives access to platforms 2 or 3 regardless of position of 6 BUT ALSO acts as trap against movements outs of both the loop and CS. 

When 5 is normal, 6 needs to choose whether the turntable road goes to loop or to CS

When 5 is reverse, 6 needs to choose whether you are departing from the loop or from CS.

I'm not sure that 6 wouldn't be done by two hand points and if it's a Peco double slip, without checking I'm not sure whether the tie bar arrangements even let you do this?

 

I should have spotted 10 and trap 11 being effectively a crossover that should definitely be on the same lever!

 

[Jeremy Cumberland]

15 minutes ago, Lacathedrale said:

I'm sorry, I'm getting muddled up trying to figure this one out. I've re-written this reply a few times trying to puzzle what the implications are :( Do you mean right hand while approaching from direction of travel, or right hand from the plan's birds eye view?

My left and right hand are as you look at the plan.

[Lacathedrale]

Yes, the Peco turnouts have a single bar for both roads on either side of the turnouts:

 

 

Is this what you meant?

 

I can't quite see how this works though, because getting from the up/down main to carriage siding requires 5R in the throat, but 5N in the slip? It seems to defeat the whole point if using a double-slip in the first place if I can only cross it in one route?

 

I'm starting to think it might be better to just have these as three separate levers, my brain is like scrambled egg!

Edited February 15 by Lacathedrale

[Jeremy Cumberland]

1 minute ago, Lacathedrale said:

I can't quite see how this works though, because getting from the up/down main to carriage siding requires 5R in the throat, but 5N in the slip?

5N has to be down main to platforms 2/3 and Loop/Carriage siding to Turntable road. I think you might have drawn the double slip (underneath the number backgrounds) with the X as the normal position and the two slip lines as reverse. If you have separate control of all four pairs of switches, this is possible (unusual, perhaps), but you can't have this if both pairs of switches at each end are co-acting.

 

6 minutes ago, Lacathedrale said:

I'm starting to think it might be better to just have these as three separate levers, my brain is like scrambled egg!

Double slips take a bit of getting your head around. If you have the track laid out, though, then you can easily see which route results from each switch setting. It's far easier with an actual double slip and turnout in front of you (and perhaps a wagon to run over them) than it is looking at a piece of paper.

[Lacathedrale]

Yea, good point - I hadn't considered the drawing was showing an impossilbe arrangement!

 

Refactored to show normal lies and numbers, and linked tie rods of the Double slip:

 

I think I've just had a eureka moment - because neither of the left/buffer end of the double slip is valid from the perspective of the throat, and so reversing the 5 in the throat MUST reverse that of the slip.

Edited February 15 by Lacathedrale

[Michael Hodgson]

2 minutes ago, Lacathedrale said:

Yea, good point - I hadn't considered the drawing was showing an impossilbe arrangement!

Some arrangements of the normal lie of a double slip are impossible with a single tie bar working both switches at the same end, sometimes you need to work them independently and therefore need two tie bars at one end or even at both ends.

 

Another point that's hard to get your head around is the Wide to Gauge trap (which I've yet to see modelled).  It looks like a Y point, but both switch blades are normally open and they can be worked separately using two tie bars, .  Unless one or the other of the blades is reverse they are in the middle so a runaway vehicle will fall into the dirt.  Typically used as a trap in a middle siding between two other lines, where you don't want a runaway to converge with either of the adjacent lines, although in the example below it would simply derail a runaway coming towards the camera.

 

[Grovenor]

I would put 1 and 7 on the same lever, they form a crossover between the up and down. Other than that You are there I think.

Crossover 4 and point 8 could be arranged with 8 as part of the crosover but its Hobson's choice really as either version could give the larger collision risk depending on the traffic pattern.

[WillCav]

1 hour ago, Lacathedrale said:

 

I agree with Grosvenor that 1 & 7 would be worked as a crossover together.

 

My only other suggestion is that I would swap the normal direction of 4 & 5 crossovers (and possibly 8).

 

Many signalboxes were rated according to the number of lever moves for a typical shift.  The frames were often designed to minimise lever pulls and thus signaller pay. Levers are also returned into the frame after each movement.

 

Will

[St Enodoc]

4 hours ago, WillCav said:

Levers are also returned into the frame after each movement.

Only if there's an inspector taking the marks...

[Lacathedrale]

13 hours ago, WillCav said:

I agree with Grosvenor that 1 & 7 would be worked as a crossover together.

 

My only other suggestion is that I would swap the normal direction of 4 & 5 crossovers (and possibly 8).

 

Many signalboxes were rated according to the number of lever moves for a typical shift.  The frames were often designed to minimise lever pulls and thus signaller pay. Levers are also returned into the frame after each movement.

 

Will

 

 

1 & 7 becoming just '1' makes sense and so done :)

 

I'm not sure about the normal lie change for 4 and 5 -  could you please explain your logic behind the change? It would appear that the down main would then run into the loop as normal, and arrivals into both P3 and P2 would require 4 to be reversed. The connection between 4 and 8 is only used for departures from P2.

[Jeremy Cumberland]

I think @WillCav must have made a mistake with 5, perhaps not realising the bottom two lines are non-passenger (there are no labels on the "blue" diagram).

 

It makes no sense to me for 4 as drawn to be normal the other way, but 4b and 8 could form a crossover on one lever (with the normal direction as shown on your drawing), and 4a (the platform 2/3 points) would then be on their own and could be normal either way depending on whether platform 2 or platform 3 was the main arrivals platform, but this has already been covered:

14 hours ago, Grovenor said:

Crossover 4 and point 8 could be arranged with 8 as part of the crosover but its Hobson's choice really as either version could give the larger collision risk depending on the traffic pattern.

 

Ideally, the main route into the station and the main route out of the station will both have all points levers normal in the frame. You have this in your latest plan with arrivals going into platform 2 and departures starting from platform 1.

[Lacathedrale]

Updated track diagram:

 

For the sake of convenience I've kept the original numbers for the levers. I appreciate these will all change in due course:

 

1 - Down Main Crossover - requires FPL

2 - Up Main Crossover - requires FPL

3 - spare

4 - Platform 2/3 Crossover - requires FPL

5 - Sidings/P3 Crossover - requires FPL

6 - Headshunt

7 - spare

8 - Platform 1 access - requires FPL

9 - spare

10 - Loco Siding

12 - Platform 3 Loop crossover

Edited February 16 by Lacathedrale

[Lacathedrale]

1 hour ago, Jeremy Cumberland said:

Ideally, the main route into the station and the main route out of the station will both have all points levers normal in the frame. You have this in your latest plan with arrivals going into platform 2 and departures starting from platform 1.

 

Excellent, thank you - I could reassign 4-8 as 8-8 and then have the remaining 4 normal to have arrivals defaulting to P3, but half the fun in this layout is likely to be the shunting around of carriage stock from trapped locos - so I don't want to make things too easy for myself.

 

I guess the biggest take-away from this is that I need each lever to be able to potentially make two circuits for two separate point motors. If I'm using mechanical interlocking that's all that's required and I think based on the complexity required for FPLs and signal levers to electronically interlock it'd just be simpler to use mechanical locking :)

Edited February 16 by Lacathedrale

[Lacathedrale]

My first attempt at signalling:

 

 

I understand that yellow shunt signals can be passed at danger, and all of those so noted appear to be able to be passed as such. I am however, not at all sure if 'yellow shunt signals' as even a thing in 1911. Though the LBSCR/SR were quite generous with their shunt signals, I feel as though these would all be through hand signals/etc. from the signalbox rather than in situ. If anyone has advice on this it would be gladly appreciated!

 

Signals 1-3 and 4-6 are home and calling on/shunt signals for the platforms. I understand this could also be represented as distant and stop signals respectively, but ringed shunt arms are slightly more unusual than fishtails so I'm likely to keep this as is. Signals 7 and 8 are for the loop and dock, could potentially be condensed into a single signal but I can see arguments both ways.

 

Signals 11-13 are starter signals for departure on those platforms, and 14-16 are shunt signals for carriage marshalling and pilot movements.

 

Signal 16 is a shunt for the pilot loco siding.

 

Signal 17 is notionally the limit of shunt as advanced starter and would probably also have a slotted distant on it (for we imagine a junction slightly further along)

 

 

Edited February 16 by Lacathedrale

[Michael Hodgson]

Some renumbering required ... you've got two 16s!  Also two 14s.

You've only shown one signal for the pilot siding, rather than one in and one out.  So I assume that's not a signal but a point indicator - worked by the point lever?  Might well be correct practice for your era.

You also need a shunt signal (or five) back from the Up line at 2 crossover. 

 

7&8 would be combined if 6 were a hand lever in the yard.

 

1-3 would not be distant signals although I believe the LBSC did use fishtailed stop arms in some places to indicate line clear to the stop blocks, with subsidiary signals for a partly occupied platform, but not sure when this was discontinued (probably more Victorian era than Edwardian).  I think it was a way of coping with poor visibility under a soot-begrimed train shed roof.  Proper distants (off-scene in your diagram) would still have had red arms (and worked by green levers) until the 1920s.

 

I don't know about LBSC practice, but I suspect 9 & 10 would be absent, movements authorised by hand-signal from the fireman or a shunter.  If not I woud have thought they would be worked from a ground frame along with the engine release crossover.

 

I'm no expert on LBSC but I suspect yellow shunts generally came in about the mid 1920s, so probably wrong for your era.

[Lacathedrale]

Thank you @Michael Hodgson! Some renumbering  as below:

 

Missing pilot siding shunt signal - I'm not that smart, I'm afraid! Added as 18.

 

P3 Runaround Loop - I am happy to omit 9 & 10 and save me the trouble of building and motorising them. The ground frame unlock lever (12) would be interlocked with 3/6/13/16 in some way, so I don't feel that the crossover requires signals. I'm happy to be disabused of this notion!

 

Shunt signals to loop/dock: I have condensed the original 7&8 into a single 7

 

Shunt signals from loop/dock/headshunt - 19/20/21 are all suitable positions for yellow shunt signals, but according to https://www.railsigns.uk/sect3page3.html these were not in use until post-1925. I am not about to double-up these for the sake of it, so I am thinking of omitting them entirely unless there is compelling evidence to the contrary. Thoughts?

 

 

[bécasse]

Ground signals which became yellow post-circa 1930 were red before that and were simply ignored unless the road was set towards the running line. If you just ignore their provision, you won't get BoT permission to open your station to passenger traffic, ground signals (or point indicators) from sidings onto running lines were a legal requirement from quite an early date (unless the points were worked by an immediately adjacent ground frame).

 

It is quite likely that the release crossover would have been worked by a local ground frame (probably 2 levers - lock/release and crossover normal/reverse) with a mechanical (ie rod) release from the box and would not have been signalled.

 

The LBSCR used home and distant signals for entry into platforms, not homes and shunts or calling-on signals, the distant on indicated that the platform was partially occupied. Not only did this practice continue throughout the LBSCR period but it was then adopted by the Southern Railway for termini with colour light signalling, the last such installation being the new Cannon Street box of 1958. In the LBSCR era distant signals were red, yellow only being adopted (slowly) from 1926 onwards.

 

With an advanced starting signal you don't need (and shouldn't provide) shunt signals. The BoT wouldn't allow shunting towards the down line and shunting towards the up line would be authorised by the platform starting signal. Just because today's preserved lines are festooned with signals as if they were fairy lights doesn't mean that that was what was done in the past. Every signal cost money (ie shareholders' dividends) to provide and they weren't provided if they weren't necessary (unless you are modelling the NER).

[Lacathedrale]

8 hours ago, bécasse said:

Ground signals which became yellow post-circa 1930 were red before that and were simply ignored unless the road was set towards the running line. If you just ignore their provision, you won't get BoT permission to open your station to passenger traffic, ground signals (or point indicators) from sidings onto running lines were a legal requirement from quite an early date (unless the points were worked by an immediately adjacent ground frame).

 

It is quite likely that the release crossover would have been worked by a local ground frame (probably 2 levers - lock/release and crossover normal/reverse) with a mechanical (ie rod) release from the box and would not have been signalled.

 

The LBSCR used home and distant signals for entry into platforms, not homes and shunts or calling-on signals, the distant on indicated that the platform was partially occupied. Not only did this practice continue throughout the LBSCR period but it was then adopted by the Southern Railway for termini with colour light signalling, the last such installation being the new Cannon Street box of 1958. In the LBSCR era distant signals were red, yellow only being adopted (slowly) from 1926 onwards.

 

With an advanced starting signal you don't need (and shouldn't provide) shunt signals. The BoT wouldn't allow shunting towards the down line and shunting towards the up line would be authorised by the platform starting signal. Just because today's preserved lines are festooned with signals as if they were fairy lights doesn't mean that that was what was done in the past. Every signal cost money (ie shareholders' dividends) to provide and they weren't provided if they weren't necessary (unless you are modelling the NER).

 

Thank you, @bécasse - I was basing my initial signalling ideas off Mr. Denny's Buckingham - his consideration was that signals should also energise model railway track sections, and so needed many discrete signals to support the exact moves proposed. I'm pleased to see in real life it would be significantly less!

 

Ground Signals - removed 21, but made 19 and 20 red.

 

Release Crossover - I had already expected this to be a ground frame, hence 'G', with 12 being the release.

 

Distant vs Shunt Ahead - Fair point, and I understand the distants would be red fishtails, but to keep things easy to edit on the diagram they are for now marked in yellow.

 

Platform Shunts - Also a fair point, removed. Presumably the platform shunt signals would be required if no 17 was the home signal for the next box along, rather than being an advanced starter?

 

Here is a further slimmed down signalling diagram taking your advice into account, in what I hope is the final iteration:

 

 

 

 

 

 

I have numbered as follows:

 

1 & 2 - Down Crossover w/ FPL

3 & 4 - Loop Crossover w/ FPL

5 & 6 - P2/3 Crossover w/ FPL

7 - Loop/Dock Point

8 - Ground frame release

 

10 - Siding shunt signal

11-13 - Platform Homes

14-16 - Platform Distants

 

17 - Advanced Starter

18-20 - Platform Starters

21-22 - Shunt Signals

23-24 - Pilot Siding Signals

 

25 & 26 - Pilot Siding and FPL

27 + 28 - P2 Departure Point

29 + 30 - P3 Departure Crossover

 

My logic for this is that starting at one end and working inwards from either end, a signalman can pull off the turnouts in routed sequence for the arrival or departure of a train, ending in either Platform distants or the Advanced starter which straddle the middle of the frame. In order to facilitate that I have changed the normal lie of what is now 5+6 so they only need to be reversed for arrival into P2, which is the same end of the frame for the rest of the arrival points and signals.

 

I'm quite happy with this and hope it's the last iteration!

 

 

Edited February 17 by Lacathedrale

[bécasse]

"Platform Shunts - Also a fair point, removed. Presumably the platform shunt signals would be required if no 17 was the home signal for the next box along, rather than being an advanced starter?"

 

If this were the case no.17 would still be slotted by the terminus box and the block section would be one of those no longer than the width of the signal post - they did exist in congested areas. The slotting would ensure that, if the platform starters were cleared just for a shunt move, no. 17 would be on. Incidentally, normally no.17 would have to be sited sufficiently far in advance to allow a complete train to be shunted (from one platform to another) without needing to pass it. If circumstances dictated, the need to locate in advance of an overbridge for example, that it couldn't be located that far in advance, a subsidiary "shunt forward" arm would be added allowing a train to enter the block section sufficiently to be able to undertake the required shunting move but no further. I seem to recollect that there was(is?) an example on the up road at Sheffield Park on the Bluebell, but they weren't uncommon on the LBSCR.