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Opinions sought on using a leverframe to control my layout


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1 hour ago, The Stationmaster said:

No.  There was  in the past very limited interlinking between signals and token etc machines.  Over the years this changed to what became the fairly universal situation of the Section Signal (the signal which admitted a trains into the section in advance, wherever it is) being released by withdrawl of a token at the signalbox which operates it.  Thus there is absolutely nothing, apart from the need for co-operative action by the two Signalmen involved, which physically prevents a token being drawn from a machine while a shunt movement is outside the Home Signal unless a token, or a Shunting Token, had been drawn for that shunting movement.

In this sort of working the Home Signal is effectively a marker of an equivalent to Station Limits and all that is happening is that s hunt is being made outside Station Limits under a well established procedure provided for in the Block Regulations.  The position of the Home Signal is in effect almost immaterial because what matters is that the movement will be made outside it - i.e. it will end up in rear of the Home Signal.

 

The siting of the Home Signal needs to be more specifically related to any points rather than looking at it as a way of circumventing  application of a Block Regulation.   All that is happening is that a movement will be made outside the physical protection of the signal and that movement will be authorised, and then protected, by the application of a Block Regulation.  In some locations where such movements were made frequently special Shunting Tokens might be provided or the normal token etc might be handed to the Driver but an exception clause in the Regulation also allowed the procedure where that was not possible (or provided for in the Signal Box Footnotes - i.e. additional Instructions relevant only to the working of that particular signal box).  

 

There were places where this sort of move was an everyday occurrence and it wevn comes as sounding a bit unusual to past railwaymen with no experience of working on single lines who sometimes seem to think there should be something like an Advanced Starting signal to prevent the shunting movement going to far.  But as I mentioned previously Advanced Starting Signals were a rarity on single lines in days gone by - it's only the preservationists who have littered their railways with them (for very good reasons as it happens).  

 

So no need to worry about moving the Home Signal and just for your amusement the last time I did this move for real (back in the 1970s) it was with a long passenger train (oh and there was another train already in the single line section but it was heading away from the station where we did the deed - and that was also permitted).

Hi Mike

Thanks for this very clear explanation.

I hope this isn't going OT from Bucket of Steam's original query but, though I'm no expert on signalling, my grandfather wasa  signalman and as a child I was allowed to visit his box so I do find this fascinating though often confusing. 

 

I've been looking through the signalling and track diagrams in the OPC volumes on "Selected Great Western Stations" and the GW did seem to be rather fond of advanced starter signals on single track lines presumably where shunting moves commonly used the main line track. Many had more than that with a starting signal, intermediate advanced starting signal and an advanced starter. Kingsbridge had an up main and an up bay starter at the platform ends, an up main advanced starter and an up main outer advanced signal with a subsidiary shunting signal- something that also seemed quite common for the GWR at least 

 

The bit I don't understand is that the home signal protecting the station was often closer in than the advanced starter. Why was it not at the outer limit of shunt where it would have protected any shunting moves within the station limits? Was that simply because it would have put the distant signal further from the box than the maximum distance over which signals were permitted to be operated (though that wouldn't seem to apply to termini with fixed distants)?

 

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6 minutes ago, Pacific231G said:

Hi Mike

Thanks for this very clear explanation.

I hope this isn't going OT from Bucket of Steam's original query but, though I'm no expert on signalling, my grandfather wasa  signalman and as a child I was allowed to visit his box so I do find this fascinating though often confusing. 

 

I've been looking through the signalling and track diagrams in the OPC volumes on "Selected Great Western Stations" and the GW did seem to be rather fond of advanced starter signals on single track lines presumably where shunting moves commonly used the main line track. Many had more than that with a starting signal, intermediate advanced starting signal and an advanced starter. Kingsbridge had an up main and an up bay starter at the platform ends, an up main advanced starter and an up main outer advanced signal with a subsidiary shunting signal- something that also seemed quite common for the GWR at least 

 

The bit I don't understand is that the home signal protecting the station was often closer in than the advanced starter. Why was it not at the outer limit of shunt where it would have protected any shunting moves within the station limits? Was that simply because it would have put the distant signal further from the box than the maximum distance over which signals were permitted to be operated (though that wouldn't seem to apply to termini with fixed distants)?

 

 

David,

 

Please feel free as far as I'm concerned it's all on topic and very interesting stuff.

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19 minutes ago, Bucket of Steam said:

 

David,

 

Please feel free as far as I'm concerned it's all on topic and very interesting stuff.

Thanks

I've now found that Mike (Statonmaster) explained this very well back in January in the topic

"Verification of signal placement please". 

I think I should maybe go back to disques rouge (single deferred stop signals that protected stations and any shunting moves from a long way back)  and VUSS (SNCF's single line simplified signalling regime)  which doesn't require any operated signals at all - though wouldn't be allowable for the density of traffic most of us subject our model branch lines to.

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David,

 

I know nothing about French railways { but I found the Burt Lancaster film 'The Train' fascinating  ).  I'm sure i'll be running more trains than would be typical for my little branch line, but there again my little 4mm figures have nothing else to do to occupy their time hahah

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2 hours ago, Pacific231G said:

Hi Mike

Thanks for this very clear explanation.

I hope this isn't going OT from Bucket of Steam's original query but, though I'm no expert on signalling, my grandfather wasa  signalman and as a child I was allowed to visit his box so I do find this fascinating though often confusing. 

 

I've been looking through the signalling and track diagrams in the OPC volumes on "Selected Great Western Stations" and the GW did seem to be rather fond of advanced starter signals on single track lines presumably where shunting moves commonly used the main line track. Many had more than that with a starting signal, intermediate advanced starting signal and an advanced starter. Kingsbridge had an up main and an up bay starter at the platform ends, an up main advanced starter and an up main outer advanced signal with a subsidiary shunting signal- something that also seemed quite common for the GWR at least 

 

The bit I don't understand is that the home signal protecting the station was often closer in than the advanced starter. Why was it not at the outer limit of shunt where it would have protected any shunting moves within the station limits? Was that simply because it would have put the distant signal further from the box than the maximum distance over which signals were permitted to be operated (though that wouldn't seem to apply to termini with fixed distants)?

 

Perhaps (definitely!) I should have made the context a bit clearer.  You'll certainly find West Country branches where there was an Advanced or (as at Kingsbridge) an Outer Advanced Starting Signal but the vast majority of intermediate stations on single lines did not have them - there were exceptions of course.

 

But we need to take a step back to where we start from.  If you made a shunt into a single line section the key feature was the outermost Home Signal.   And almost invariably you wouldn't find very many stations with an Additional Home Signal further from the signal box than the most advanced Starting Signal which applied in the opposite direction to the same line - as you have noticed.  The reason for this was probably economy because additional signals cost money, both to provide in the first place and then to maintain but they were only worth providing if they delivered a traffic working advantage and in order to deliver that advantage they had to be a minimum of 440yds in rear of the next Home Signal because that was the distance needed to create a Clearing Point - the length of line which had to be clear in order for a Signalman to accept a train from the signal box in rear.  

 

The normal Clearing Point on a single line was not 440yards (which it would be on a double) but depended on the nature of the station/crossing loop or what have you.  Thus on the GWR the Clearing Point at single line crossing loop was the Starting Signal at the far end of the loop which the train would enter, irrespective of the distance between the Home Signal and that Starting Signal.  On the GWR (and the WR until 1960) at a terminus the line had to be clear from the Home Signal to the place where a train would normally stop (in 1960 it was altered to the line had to be clear from the Home Signal to the station stop blocks, somewhat less ambiguous than the GWR wording).   Thus only time an Additional Home Signal would be justifiable would be if there were regular circumstances which prevented a Clearing point being established, e.g. the platform line was regularly blocked by a train which could not be shunted out of the way.  Although Kingsbridge was a busy station for seasonal passenger traffic even in the 1930s the GWR obviously considered that with a bay platform and a carriage siding there would be no trouble clearing the platform line to allow another train to be accepted so even then they did not add a second Home Signal.

 

As you mentioned providing an additional Home Signal would obviously push the Distant signal firther away because braking would now be to a signal 440 yards furether from the Home signal.  But I doubt this was really a factor in not having the additional Home Signal because all it meant was that the Signal Lampman had an extra half mile to walk once every week and an extra 10 minutes of walking once a week probably wasn't likely to cost anything except his shoe leather.  The key point was whether or not traffic reasons justified provision of an additional Home Signal.

 

As far as the shunt into the section is concerned if it were to be protected by an additional Home Signal logically that signal would have to be at least 440 yards beyond the furthest point any shunt would be likely to go - that basically means 440 yards beyond any Advanced Starting Signal in order to create a Clearing Point when a shunt is outside the Home Signal.  The modern day South Devon Railway have in fact created exactly that situation at both Buckfastleigh and Bishops Bridge - very different from what was once there (Bishops Bridge signal box didn't even exist in pre-preservation days).   

 

Incidentally - as at Kingsbridge - it was not unusual for Starting Signals (including the Outer Advanced Starting Signal at Kingsbridge to have subsidiary shunt ahead arms which meant that it was known that regular shunting beyond those signals would be needed.  Hardly surprising at Bodmin where the Advanced Starting Signal was nearer to the station stop blocks than the Home Signal on the Bodmin Road line but at Kingsbridge the sub was mounted below a signal which was 160 yards further from the stop blocks than the Home Signal.  but it made no difference to the way the shunting movement was dealt, the critical thing being whether or not it went out onto the single line in rear of/outside the protection of the Home Signal.

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On 03/10/2020 at 18:57, Bucket of Steam said:

Wow, this is a complicated as trying to do file transfers between an IBM mini computer and an ICL C03 system ( before TCP/IP ruled the world.)

File transfers?  You were lucky! In 1973 my data was on stacks of card and if I didn't want to sort them by hand I had to write Fortran programs on punch cards . That were real work lad! 

 

Mike. Thanks very much for explaining this so patiently. In situations where shunting did take place beyond the last signal on a single or opposite drection line was it normal to have a Limit of Shunt board or were they just used when a shunting move going to far would create a particular hazard?

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3 minutes ago, Pacific231G said:

File transfers?  Your were lucky! In 1973 my data was on stacks of card and if I didn't want to sort them by hand I had to write Fortran programs on punch cards . That were real work lad! 

 

Mike. Thanks very much for explaining this so patiently.

David,

 

Funny enough the file transfer was done with each computer sending files to what appeared to it,  to be a printer, and reading from what it thought was a card reader.  The computers were about 150 miles apart , and connected by a slooooow telephone modem.

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55 minutes ago, Pacific231G said:

File transfers?  Your were lucky! In 1973 my data was on stacks of card and if I didn't want to sort them by hand I had to write Fortran programs on punch cards . That were real work lad! 

 

Mike. Thanks very much for explaining this so patiently. In situations where shunting did take place beyond the last signal on a single or opposite drection line was it normal to have a Limit of Shunt board or were they just used when a shunting move going to far would create a particular hazard?

As I very carefully explained a decade or so back to somebody (a signal engineer as it happens) on a heritage railway who was in the process of installing a Limit of Shunt board on a single line it is not logical to do that.   LoS boards (and now their double red GPL replacements) apply to movements being made in the wrong direction on a running line and you can't do that in normal working on a single line because movements take place in both directions.

 

The relevant Regulations were dead simple - the movement only went as far as was necessary to clear any points for shunting purposes    Different arrangements applied if there happened to be a ground frame operated connection to which the shunt move was being made.  So when I had that nice long loco hauled passenger shove back onto a single line it only went as far as was necessary to clear the points to allow it to crossover to the other side of the loop - even if it did mean a loco and c.10 coaches standing outside the Home Signal before reversing.

 

In fact even on double lines the vast majority of stations with yards or sidings which were shunted from running lines did not have LoS boards.  

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On 03/10/2020 at 17:56, The Stationmaster said:

Perhaps (definitely!) I should have made the context a bit clearer.  You'll certainly find West Country branches where there was an Advanced or (as at Kingsbridge) an Outer Advanced Starting Signal but the vast majority of intermediate stations on single lines did not have them - there were exceptions of course.

 

But we need to take a step back to where we start from.  If you made a shunt into a single line section the key feature was the outermost Home Signal.   And almost invariably you wouldn't find very many stations with an Additional Home Signal further from the signal box than the most advanced Starting Signal which applied in the opposite direction to the same line - as you have noticed.  The reason for this was probably economy because additional signals cost money, both to provide in the first place and then to maintain but they were only worth providing if they delivered a traffic working advantage and in order to deliver that advantage they had to be a minimum of 440yds in rear of the next Home Signal because that was the distance needed to create a Clearing Point - the length of line which had to be clear in order for a Signalman to accept a train from the signal box in rear.  

 

The normal Clearing Point on a single line was not 440yards (which it would be on a double) but depended on the nature of the station/crossing loop or what have you.  Thus on the GWR the Clearing Point at single line crossing loop was the Starting Signal at the far end of the loop which the train would enter, irrespective of the distance between the Home Signal and that Starting Signal.  On the GWR (and the WR until 1960) at a terminus the line had to be clear from the Home Signal to the place where a train would normally stop (in 1960 it was altered to the line had to be clear from the Home Signal to the station stop blocks, somewhat less ambiguous than the GWR wording).   Thus only time an Additional Home Signal would be justifiable would be if there were regular circumstances which prevented a Clearing point being established, e.g. the platform line was regularly blocked by a train which could not be shunted out of the way.  Although Kingsbridge was a busy station for seasonal passenger traffic even in the 1930s the GWR obviously considered that with a bay platform and a carriage siding there would be no trouble clearing the platform line to allow another train to be accepted so even then they did not add a second Home Signal.

 

As you mentioned providing an additional Home Signal would obviously push the Distant signal firther away because braking would now be to a signal 440 yards furether from the Home signal.  But I doubt this was really a factor in not having the additional Home Signal because all it meant was that the Signal Lampman had an extra half mile to walk once every week and an extra 10 minutes of walking once a week probably wasn't likely to cost anything except his shoe leather.  The key point was whether or not traffic reasons justified provision of an additional Home Signal.

 

As far as the shunt into the section is concerned if it were to be protected by an additional Home Signal logically that signal would have to be at least 440 yards beyond the furthest point any shunt would be likely to go - that basically means 440 yards beyond any Advanced Starting Signal in order to create a Clearing Point when a shunt is outside the Home Signal.  The modern day South Devon Railway have in fact created exactly that situation at both Buckfastleigh and Bishops Bridge - very different from what was once there (Bishops Bridge signal box didn't even exist in pre-preservation days).   

 

Incidentally - as at Kingsbridge - it was not unusual for Starting Signals (including the Outer Advanced Starting Signal at Kingsbridge to have subsidiary shunt ahead arms which meant that it was known that regular shunting beyond those signals would be needed.  Hardly surprising at Bodmin where the Advanced Starting Signal was nearer to the station stop blocks than the Home Signal on the Bodmin Road line but at Kingsbridge the sub was mounted below a signal which was 160 yards further from the stop blocks than the Home Signal.  but it made no difference to the way the shunting movement was dealt, the critical thing being whether or not it went out onto the single line in rear of/outside the protection of the Home Signal.

 

It's very interesting to see how things were done and compare with the differences on preserved railways now. 

 

I'm a signalman at the Mid-Hants (currently just Alresford 'box) - at Alresford we have the arrangement you describe in your penultimate paragraph, with an outer home 440+ yards beyond the advanced starter - quite useful if there's shunting going on first-thing, as the light engine for the first service train can be accepted before the shunting has finished.

 

At Medstead & Four Marks, however, the signalling is much more like it was in pre-preservation days (not quite the same as the up platform is now bidirectionally signalled to allow trains to depart in the down direction), with no outer homes or advanced starters - so the clearing point in both directions is the starting signal, and the sections have to be occupied for any shunting moves or run-rounds. In this case though, a token has to be removed for shunting purposes (allowing the starter to be cleared), and retained by the signalman - is this a more modern rule?

 

Of course most preserved lines have a much more intensive timetable than they ever would have had in pre-preservations days - in BR days Alresford was the only crossing place between Winchester and Alton, and I think the service was 2-hourly...

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In olden tymes the Mid-Hants line stations had a peculiar arrangement of advanced starters but no outer homes (down direction only at Medstead).  I've never been able to find a convincing explanation for this.  I can only assume that it was to facilitate shunting onto the single line in conjunction with Tyers no. 3 (non-returnable) tablet instruments - presumably the advance starter was the section signal and locked by the tablet.

 

The present administration has installed outer homes and advanced starters at all stations except Medstead, where this is impractical due to the gradients either side of the station.

 

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1 hour ago, Nick C said:

 

It's very interesting to see how things were done and compare with the differences on preserved railways now. 

 

I'm a signalman at the Mid-Hants (currently just Alresford 'box) - at Alresford we have the arrangement you describe in your penultimate paragraph, with an outer home 440+ yards beyond the advanced starter - quite useful if there's shunting going on first-thing, as the light engine for the first service train can be accepted before the shunting has finished.

 

At Medstead & Four Marks, however, the signalling is much more like it was in pre-preservation days (not quite the same as the up platform is now bidirectionally signalled to allow trains to depart in the down direction), with no outer homes or advanced starters - so the clearing point in both directions is the starting signal, and the sections have to be occupied for any shunting moves or run-rounds. In this case though, a token has to be removed for shunting purposes (allowing the starter to be cleared), and retained by the signalman - is this a more modern rule?

 

Of course most preserved lines have a much more intensive timetable than they ever would have had in pre-preservations days - in BR days Alresford was the only crossing place between Winchester and Alton, and I think the service was 2-hourly...

The situation at Medstad sounds very much  to be something imposed by the present owners because that was certainly not the case in the SR Block Regulations (which were basically no different from the GWR Regulations and, no doubt, the RCH 'standard' Regulations.

 

On a heritage line numerous things, but especially operational safety, have to be looked at in a different way from the way they were done on the 'big railway' because you are dealing with volunteers (who might only be there infrequently) plus there is a whole raft of safety related legislation and rsk assessments which now apply and didn't in the past.  Doing an risk assessment (RA) on what could be done at Medstead there are various things to consider because it is different from those locations without an Outer Home Signal sufficiently far out to protect a shunting movement without the need to Block Back.  

 

So the fact that it is different means that you need to not only cater for that but also avoid confusion.   In order to add belt & braces to protecting the movement a token etc is drawn (and retained by the Signalman) and what that also does is prevent another train being accepted because it reminds the Signalman (who while at Alresford could accept a train if he/she was making a similar shunt).  Plus obtaininga token means teh Starter can be cleared which also ensures that the points are correctly set thereby avoiding an 'I thought the points ...' type of derailment.   The Driver doesn't need a token, tablet or whatever to shunt at Alresford so giving him one at Medstead might cause him to think he has authority to go through the section - so the Signalman hangs on to it.

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2 hours ago, Nick C said:

 

It's very interesting to see how things were done and compare with the differences on preserved railways now. 

 

I'm a signalman at the Mid-Hants (currently just Alresford 'box) - at Alresford we have the arrangement you describe in your penultimate paragraph, with an outer home 440+ yards beyond the advanced starter - quite useful if there's shunting going on first-thing, as the light engine for the first service train can be accepted before the shunting has finished.

 

At Medstead & Four Marks, however, the signalling is much more like it was in pre-preservation days (not quite the same as the up platform is now bidirectionally signalled to allow trains to depart in the down direction), with no outer homes or advanced starters - so the clearing point in both directions is the starting signal, and the sections have to be occupied for any shunting moves or run-rounds. In this case though, a token has to be removed for shunting purposes (allowing the starter to be cleared), and retained by the signalman - is this a more modern rule?

 

Of course most preserved lines have a much more intensive timetable than they ever would have had in pre-preservations days - in BR days Alresford was the only crossing place between Winchester and Alton, and I think the service was 2-hourly...

The pre-preservation Alresford was rather unusual IMHO because, in addition to having an Up Advanced Starting, there was also a subsidiary arm below the Up Starting (apparently known colloquially as the 'watercress' signal on account of being used i/c/w the shunting of watercress trains). This signal apparently was used to enable trains in the Up loop to 'draw past' the Up Starting in order to shunt back into the Up Siding - but given the existence of an Up Advanced Starting then why not just use the Up Starting? I've never seen a similar provision elsewhere - any such 'shunt ahead' arm usually existed only where the main arm above it was the section signal. This arrangement continued well into BR days, even to the extent that original L&SWR 'diamond' LQ arm was replaced by BR(S) UQ arm with associated indicator. Sadly I've yet to find an electrical locking table for Alresford in that period.

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