Decoding some mysterious signal diagram icons

[Lacathedrale]

Hello there all,

 

With some very kind help from the S-R-S I've got a signalling diagram for a station I'm thinking of building, but it has some icons I've not come across before and I was wondering if it might be possible to get some help?

 

 

This would appear to be an AWS cancelling indicator? I can't seem to find a human-readable explanation of what this means

 

This is a white diamond, to indicate that there is no telephone provided and the driver/fireman doesn't need to contact the signal box?

 

 

This is a semaphore shunting signal - no idea what 8y or L is? There are other icons for fouling bars/treadles with letters (and a few more of the type incidated at 'L' ) nearby - I'm assuming they are warning/feedback to the signalman - but what ARE they?

 

 

No 2. is a shunt signal for reversing into the sidings at above the two platform roads?

No 10 is a shunt signal for reversing into sidings below the two roads

I don't understand  how 3. and 4. work with a single semaphore arm, or what the hump underneath signifies? A later diagram (shown below) has a route indicator which presumably sets the display and clears the signal - but not sure how this would work in the above context?

 

An actual photograph of the gantry is here:

 

Any help or advice would be appreciated!

 

Cheers!

Edited June 2, 2020 by Lacathedrale

[RailWest]

4 minutes ago, Lacathedrale said:

Hello there all,

 

With some very kind help from the S-R-S I've got a signalling diagram for a station I'm thinking of building, but it has some icons I've not come across before and I was wondering if it might be possible to get some help?

 

 

This would appear to be an AWS cancelling indicator? I can't seem to find a human-readable explanation of what this means

 

It's a Limit of Shunt board.

 

 

4 minutes ago, Lacathedrale said:

 

This is a white diamond, to indicate that there is no telephone provided and the driver/fireman doesn't need to contact the signal box?

 

It's a diamond signal to indicate to the driver that he is exempt from certain parts of Rule 55. Nothing to do with telephones, although often one would be provided at such a signal.

 

4 minutes ago, Lacathedrale said:

 

 

This is a semaphore shunting signal - no idea what 8y or L is? There are other icons for fouling bars/treadles with numbers, and a few more of the type incidated at 'L' spread around.

 

'8' is the signal number. 'Y' indicates that it is a 'yellow' shunt rather than the normal red. The symbol next to 'L' is for a treadle, so 'L' may simply be the identifier for that particular treadle (if there is more than one in the area).

 

4 minutes ago, Lacathedrale said:

 

 

No 2. is a shunt signal for reversing into the sidings at above the two platform roads?

No 10 is a shunt signal for reversing into sidings below the two roads

I don't understand  how 3. and 4. work with a single semaphore arm, or what the hump underneath signifies? A later diagram (shown below) has a route indicator which presumably sets the display and clears the signal - but not sure how this would work in the above context?

 

Is this is Southern location?

 

The ring would indicate a signal leading into a goods line, so 2 reads into the diverging route at 6 and 10 reads into the diverging route at 9.

The 'hump' is a (probably mechanical) route indicator for the stop signal above it, which can be worked by either 3 or 4 as required and the RI will show the appropriate indication automatically.

 

4 minutes ago, Lacathedrale said:

 

An actual photograph of the gantry is here:

 

Any help or advice would be appreciated!

 

Cheers!

 

 

See my comments in red interspersed in your notes.

 

[Lacathedrale]

That's very helpful, thank you - regarding the first (box with cross in it), I didn't realise the AWS cancelling indicator had an outlined cross instead of a plain cross, which threw me

 

So, the yellow shunt signal indicates that a train can pass it at STOP into the straight route (since it appears to be governing access off the curved route)? This would be the siding adjacent the gantry signals in the next snippet, so would make sense - access to the headshunt.

 

With regard to the route indicator/etc. yes - the location is on the SR (ex-SECR if that makes a difference). A route indicator makes sense - are there any photographs of such a device? The 1977 version seems fairly self explanator and I'm sure i've seen pictures and models, but none in a strange half-circle shape and I can't seem to make it out in the gantry photograph either. The gantry itself seems very strange - it looks like there are two poles ahead of the gantry on the up and down lines, then the main arch whose horizontal bar extends wider than the legs, and then yet another vertical leg on the far left. None of that makes much sense to me, any advice would be gladly appreciated.

[RailWest]

>>>So, the yellow shunt signal indicates that a train can pass it at STOP into the straight route (since it appears to be governing access off the curved route)?

 

Yes.

 

As regards the mechanical half-moon route indicator, Plate 104 on page 90 of Pryer's OPC "Southern Signals" book shows two of these at Redhill.

 

Which ex-SECR location please? It would be easier to answer some of the questions if we could then refer to the relevant SRS diagram :-)

Edited June 3, 2020 by RailWest

[Lacathedrale]

Hi Chris, it's Caterham - I've asked them for their terms on re-posting the signal diagram, since I paid them for it and presumably, they want to keep a source of income going, but if they are amenable I will reproduce here. In the meantime, here's the preview link:https://www.s-r-s.org.uk/html/src/R1795.htm

 

 

Presumably the treadles trigger warning boxes like these:

 

 

essentially the mechanical equivalent of a red or green LED? The fact it has 'locked' or 'free' rather than 'occupied' or 'free' implies to me there might be some interlocking involved? I'm not quire sure of the significance of the 'To XXX' section -  for example Treadle L (in my snapshot and just below the 'AM' in Caterham on the sample diagram) - would that lock crossover marked 6 and/or the FPL at 7 ? Is this just a nomenclature thing and provides no other function?

 

One thing I saw (which I probably won't model but I'm interested anyway) is the 'sprung points' on the diagram:

 

 

Presumably this forces the trap closed by down trains on the down line (depicted here) , but acts as an automatic trap point for trains that pass the limit of shunt sign?

 

I spoke to the S-R-S and they unfortunately have no files for the mechanical interlocking - which would be super handy. I was roughly able to puzzle-out the single track signalling plan and how it might work, but this feels like it's a great deal more complicated...

 

 

 

Edited June 3, 2020 by Lacathedrale

[RailWest]

1. Can you clarify please exactly what you are trying to do/understand from the signal diagram? Are you hoping to model Caterham exactly as per the signalled layout, or adapt it? Are you going for the double or single track version?

 

2. The 'spring points' would have been a typical trailing catch point, designed to be pushed shut by a train passing over it in the trailing direction the spring open again once it had passed. Can I assume that there is a steep-ish gradient uphill towards Caterham? In which case the original purpose of the catch point would have been as a safeguard in case an unfitted train came to a stand at the Down Home and then the rear portion broke away when the train re-started.

I am guessing that originally the interlocking only allowed the shunt 8 to be cleared for a movement across 9 onto the Up line and that later it was altered to allow a shunt 'wrong direction' onto the Down line as well, which is when the LoS board would have been provided.  Although the catch-point would indeed have acted as a trap for any run-away shunt moves past the LoS, it is likely IMHO to have pre-dated the LoS anyway.

 

3. Sykes instruments can be a minefield for the unwary! Similar-looking instruments can be totally different inside and identical instruments can be used for a variety of different purposes. Although some may have been provided for indication purposes only (eg 'Train Waiting' indicators), they were almost always there to provide electro-mechanical interlocking with various levers (usually signals). To understand exactly what each one did in any particular location then really you need to see the relevant Electrical Locking table.

 

[phil-b259]

2 hours ago, Lacathedrale said:

 

With regard to the route indicator/etc. yes - the location is on the SR (ex-SECR if that makes a difference). A route indicator makes sense - are there any photographs of such a device? The 1977 version seems fairly self explanator and I'm sure i've seen pictures and models, but none in a strange half-circle shape and I can't seem to make it out in the gantry photograph either. 

look closely at the signals in the background. Redhill had them on all platform starting signals due to the junction at the south end.

 

[Lacathedrale]

@phil-b259 So it looks like there's a semi-circle, with a quarter circle that pivots with the movement of the lever to hide or show the route? I can't quite see what is meant to be shown or hidden - a number? A colour?

 

37 minutes ago, RailWest said:

1. Can you clarify please exactly what you are trying to do/understand from the signal diagram? Are you hoping to model Caterham exactly as per the signalled layout, or adapt it? Are you going for the double or single track version?

 

2. The 'spring points' would have been a typical trailing catch point, designed to be pushed shut by a train passing over it in the trailing direction the spring open again once it had passed. Can I assume that there is a steep-ish gradient uphill towards Caterham? In which case the original purpose of the catch point would have been as a safeguard in case an unfitted train came to a stand at the Down Home and then the rear portion broke away when the train re-started.

I am guessing that originally the interlocking only allowed the shunt 8 to be cleared for a movement across 9 onto the Up line and that later it was altered to allow a shunt 'wrong direction' onto the Down line as well, which is when the LoS board would have been provided.  Although the catch-point would indeed have acted as a trap for any run-away shunt moves past the LoS, it is likely IMHO to have pre-dated the LoS anyway.

 

3. Sykes instruments can be a minefield for the unwary! Similar-looking instruments can be totally different inside and identical instruments can be used for a variety of different purposes. Although some may have been provided for indication purposes only (eg 'Train Waiting' indicators), they were almost always there to provide electro-mechanical interlocking with various levers (usually signals). To understand exactly what each one did in any particular location then really you need to see the relevant Electrical Locking table.

 

 

Hello Chris,

 

1. I had originally thought of modelling the pre-doubling of the station in order for it to fit comfortably to dead-scale at about 7' - but then I realised that I'm not sure I have the patience for building dozens of carriages for them all to be close-coupled and run effectively as a shuttle service anyway - so thoughts turned towards the post-doubling arrangement, with passenger services served by multiple units and freight by steam or diesel (well, one diesel - 11001 at least) - depending on the era. If I were to model either, they would both be exactly as written, rather than adapted. I'm still not 100% convinced that 13' of space is best spent on modelling of this manner, but if nothing else this is very much helping me gain greater contextual understanding that can be ported anywhere.

 

2. Caterham is in the base of the valley, so unless I'm rather mistaken (and the last time I took the train there was some time ago) the route is fairly flat, especially compared to the Oxted/east Grinstead line which goes through tunnels, over girder bridges, etc. on the valley side). Thank you for the info on the LoS board/Yellow shunt arm.

3. There's unfortunately no further information on any interlocking - I assume we can make some fairly well educated guesses that the treadles and fouling bars would interlock points which would route into occupied track (presumably with the exception of the outer fouling bars on the platforms, otherwise it'd be impossible to couple up multiple units?) . For the purposes of a layout, presumably we could have these as indicators (as a quality-of-life improvement for whoever is signalling) as well as interlocking.
 

Please see your PMs, by the way.

 

Many thanks,

Edited June 3, 2020 by Lacathedrale

[Nick C]

1 hour ago, Lacathedrale said:

Presumably the treadles trigger warning boxes like these:

 

essentially the mechanical equivalent of a red or green LED? The fact it has 'locked' or 'free' rather than 'occupied' or 'free' implies to me there might be some interlocking involved? I'm not quire sure of the significance of the 'To XXX' section -  for example Treadle L (in my snapshot and just below the 'AM' in Caterham on the sample diagram) - would that lock crossover marked 6 and/or the FPL at 7 ? Is this just a nomenclature thing and provides no other function?

 

Treadles basically provide an electrical indication that a train has passed a particular point - which can then be used to make something happen - for example ringing a bell (e.g. train waiting), or releasing something. My guess would be that in that particular case it'd be used to release an electric backlock on signal 2, so that the signalman can't put it back (and thus release FPL 7 and points 6) until the train has cleared the crossover. 

[Nick C]

5 minutes ago, Lacathedrale said:

3. There's unfortunately no further information on any interlocking - I assume we can make some fairly well educated guesses that the treadles and fouling bars would interlock points which would route into occupied track (presumably with the exception of the outer fouling bars on the platforms, otherwise it'd be impossible to couple up multiple units?) . For the purposes of a layout, presumably we could have these as indicators (as a quality-of-life improvement for whoever is signalling) as well as interlocking.

 

The signalling shown on the diagram (going by the minuature version on the SRS site) doesn't appear to allow for MUs to be coupled up in the platform - I'd expect to see a calling-on arm under the stop signal 3/4 to allow a train to be admitted to a partially-occupied platform. To clear a running signal the line has to be clear all the way to the next signal, or in this case the buffer stops.

[RailWest]

According to SRS information the line was worked by Sykes Lock-and-Block once it had been doubled. In that case, it would be a reasonable assumption IMHO that all the various treadles (L,C,G,J) in advance of the Down Home were to release the back-locks on 2,3,4 once a Down train had arrived. Treadle B would have done the same for the Up Startings and treadle A for the Up Advanced Starting.

 

Given the absence of any track-circuit or 'train waiting' treadle in rear of the Up Adv Starting, then the 'Rule 55' diamond on its post can probably accounted for by the use of Sykes L&B, which was one of the permitted reasons for exemption.

[RailWest]

According to the SRS diagram there were Electric Fouling Bars (EFB) at each end of each platform road. The ones nearer to the Starting signals also served as treadles, presumably for the Sykes back-lock releases on the Down Home. The ones nearer to the buffer-stops probably served more as reminder devices in the event that stock was left there out-of-sight of the signalman, but may well have locked the Down Homes as well.

 

Judging from the progression of the signalling as the layout was rationalised, by the time that the Down sidings loop had been removed then all the EFBs had been abolished and replaced by a single track-circuit on each platform road. A new treadle D had been installed adjacent to what had been FPL 19, presumably to replace the previous G and J by a single one serving both arrival routes, and the pointwork and FPLs in the station throat altered and re-numbered. Further changes saw more TCs installed  (and treadle D removed), until eventually there was full track-circuiting with motor points and C/L signals.

[bécasse]

The branch was definitely Sykes Lock & Block. One of the Whyteleafs had a busy level crossing which had to be closed before the block could be cleared (normally LC gates don't count as an obstruction but they did in this case), and a practice developed of closing the gates to clear the block and then using the Sykes key so that the gates could be opened again, protected by signals of course. Just one of the regular illegitimate uses of the Sykes key in that immediate area. Its use on the main line was even more prolific since the rush hour service couldn't be worked to time otherwise, the practice ceased after the Purley Oaks accident of November 1947 pushing the project to resignal the area to the top of the list (although post-war circumstances meant that it was still five years before it happened).

[bécasse]

Most Southern Electric terminals in the London suburban area had fouling bars together with indicators (a white star on a blue background) on the adjacent platform indicating their position. Stock (and locos) were required to stand such that at least some wheels were on the bar.

[Lacathedrale]

50 minutes ago, bécasse said:

... November 1947 pushing the project to resignal the area to the top of the list (although post-war circumstances meant that it was still five years before it happened).

 

Presumably this dates the new bracket signal and route indicator on the down home outside Caterham station?

 

2 hours ago, RailWest said:

According to SRS information the line was worked by Sykes Lock-and-Block once it had been doubled. In that case, it would be a reasonable assumption IMHO that all the various treadles (L,C,G,J) in advance of the Down Home were to release the back-locks on 2,3,4 once a Down train had arrived. Treadle B would have done the same for the Up Startings and treadle A for the Up Advanced Starting.

 

Given the absence of any track-circuit or 'train waiting' treadle in rear of the Up Adv Starting, then the 'Rule 55' diamond on its post can probably accounted for by the use of Sykes L&B, which was one of the permitted reasons for exemption.

 

This is the first time I'm coming across this term - my very limited reading so far (primarily here: https://dickthesignals.co.uk/onewebmedia/1A Syx lock and block basics.pdf )  has me extremely puzzled. For the purposes of model railway operation, do I need to be concerned with how these would work in an operational sense? It would appear as essentially a way for other signal boxes to permit movements (hence R55 exemption) and lock out until those movements were completed.

 

2 hours ago, Nick C said:

 

The signalling shown on the diagram (going by the minuature version on the SRS site) doesn't appear to allow for MUs to be coupled up in the platform - I'd expect to see a calling-on arm under the stop signal 3/4 to allow a train to be admitted to a partially-occupied platform. To clear a running signal the line has to be clear all the way to the next signal, or in this case the buffer stops.

 

Interesting - so why have pairs of fouling bars on each platform road? Surely one is enough?

 

The SRS has kindly advised that I can repost SS59 on the understanding that it is wholly under copyright of the Signalling Record Society:

 

S559.pdf

[73c]

Here's the Redhill route indicator ( also known as a 'dustbin ' by the sound it made). Mechanical links would move the hood to reveal a number, that was the route the train would then take.

https://www.flickr.com/photos/21602076@N05/8017276813/

 

 

Edited June 3, 2020 by 73c

[Lacathedrale]

Righto, so both sides are hidden, and one revealed by rotating the cover 90 degrees infront of the other? What did it look like behind? I realise I'm getting into the nitty gritty on this one

[RailWest]

>>>This is the first time I'm coming across this term - my very limited reading so far (primarily here: https://dickthesignals.co.uk/onewebmedia/1A Syx lock and block basics.pdf )  has me extremely puzzled. For the purposes of model railway operation, do I need to be concerned with how these would work in an operational sense? It would appear as essentially a way for other signal boxes to permit movements (hence R55 exemption) and lock out until those movements were completed.

 

Err...which term please?

[Lacathedrale]

So nice you said it thrice? Sykes Lock and Block - i.e. plungers and locked-out levers from things other than... other levers...

[73c]

http://www.bluebell-railway.co.uk/bluebell/hkwork_archive1.html

 

Click on the first picture on left to see the reverse. Shows lamp for the route stencil.

[Lacathedrale]

So there's only one lamp and stencil - and two parts that swivel (the cover, and the stencil plate inside?)

[73c]

There would be other stencils, depending on number of routes you could take, though not a huge number, maybe 3 or 4.

One lamp as that would illuminate the stencil at night from behind.

[RailWest]

 

9 minutes ago, Lacathedrale said:

So nice you said it thrice? Sykes Lock and Block - i.e. plungers and locked-out levers from things other than... other levers...

In very simple terms 'Lock and Block' is just a form of Absolute Block working for double/multiple track lines. The key difference from other systems is that the block instruments are interlocked with the signals and treadles so that the passage of trains is tracked and equipment locked/released accordingly.

 

It was designed to prevent 'simple' accidents such as a signalman accepting a train, clearing a signal, then forgetting to put the signal back behind it and accepting another train, which then ran past the 'off' signal into the back of the first train etc. Alternatively a signalman accepts a train, then forgets about it, then accepts a second train from the signalman in rear - who mistakenly assumes the first one had cleared the section - which runs into the back of the first one which was running late. Etc, etc....

 

Signals have to be 'on' with levers normal in order to accept trains. Once signals have been cleared, they can by put back after passage of the train, but not far enough to be release the interlocking on points etc until train has passed them and gone over a treadle to release the back-lock. Until all signals have been cleared, and then put back, and all treadles activated in the correct sequence, you could not accept another train from the box in rear.

[bécasse]

18 minutes ago, RailWest said:

 

Until all signals have been cleared, and then put back, and all treadles activated in the correct sequence, you could not accept another train from the box in rear.

Unless, of course, you operated the notorious "Sykes key" which reset the whole caboodle.

[Nick C]

1 hour ago, Lacathedrale said:

 

Presumably this dates the new bracket signal and route indicator on the down home outside Caterham station?

 

 

This is the first time I'm coming across this term - my very limited reading so far (primarily here: https://dickthesignals.co.uk/onewebmedia/1A Syx lock and block basics.pdf )  has me extremely puzzled. For the purposes of model railway operation, do I need to be concerned with how these would work in an operational sense? It would appear as essentially a way for other signal boxes to permit movements (hence R55 exemption) and lock out until those movements were completed.

 

 

Interesting - so why have pairs of fouling bars on each platform road? Surely one is enough?

 

The SRS has kindly advised that I can repost SS59 on the understanding that it is wholly under copyright of the Signalling Record Society:

 

S559.pdf 96.21 kB · 1 download

 

Possibly a short train would be able to get lost if only a single bar was fitted?