Signalling diagram - Have I got it basically right ? .... Can I change it a bit?

[cary hill]

Hello everybody,

 

Please find attached my interpretation of the signalling diagram and other information for Tavistock South.

 

I would grateful if knowledgeable people could check it for "schoolboy howlers", as I have "past form" for those kind of errors - omitting catch points etc..... I hope it's not too bad, because I then need advice on how to possibly "rearrange" it a bit, if it doesn't break all the rules of best signalling practice.

 

The only alteration I have made so far is to swap "up" and "down" because I'm going to teleport the track layout and most of the arrangements to the vicinity of Dartmouth and will have a "London" connection and I think you go "up" to London.

 

 

If the above gets a pass mark the queries, I have are as follows(with a background period of 1956-1963)

 

1. What is the exact purpose of the Down Intermediate Starter ?

 

2. At Tavistock South the "business" end seems to be the Plymouth end as the Shunt Arm is at that end, I assume this might be because it was originally a terminus before the onward extension to Launceston. I think I will need to make the "Exeter and London" end the "business end", so can I have another Shunt Arm at that end or move the existing one there or does it not matter? I ask because I have revised my original Kingswear "light" timetable workings after a recent South Hams Holiday/field visit. I have concluded that services beyond Dartmouth would be less frequent than I originally supposed and more Exeter/Newton Abbot services will need to terminate at/return from Dartmouth.

 

3. As there is a large discrepancy in platform lengths 480' (8 coaches) and 320'( 5 coaches) would bi-directional running/signalling be possible? If not I can live with drawing up twice or possibly not stopping at all, as this only affect one or two return through services to London/Wolverhampton, as the named services(running further in Devon now) I could use obligingly only have 5 coach portions.

 

4. I think the signal box had thirty seven levers - I can see point lever handles for some of the more remote points in the yard but how would I estimate the number actually used?

 

5. I far as I can see the signal posts at Tavistock appear to be wooden, presumably they can be teleported to Dartmouth as is (was) or could I have a mix of wooden and tubular posts?

 

I am sure I will think of something else to ask.

 

Thanks for reading this and I look forward to possible replies.

 

David

[The Stationmaster]

Some of the discs seem to be well adrift but as I'm currently being tasked off RMWeb by SWMBO I'll have a look later.

[cary hill]

Some of the discs seem to be well adrift but as I'm currently being tasked off RMWeb by SWMBO I'll have a look later.

 

I assume "some" implies three or more, however, with a second look at a more civilised hour, the three rightmost ground signals all appear to have drifted beyond or away from their proper stations unless I am very much mistaken. I assume there are others giving offence.

 

I'll look forward to your full diagnosis later should you manage to escape back to RMWeb and maybe pop along to Specsavers in the meantime.

[The Stationmaster]

Please find attached my interpretation of the signalling diagram and other information for Tavistock South.

 

I would grateful if knowledgeable people could check it for "schoolboy howlers", as I have "past form" for those kind of errors - omitting catch points etc..... I hope it's not too bad, because I then need advice on how to possibly "rearrange" it a bit, if it doesn't break all the rules of best signalling practice.

Well apart from the trap points becoming catch points there don't seem to be any howlers. The peculiar looking situation with the discs makes a lot more sense once I dug out details of the Tavvy South diagram which shows various discs on the 'wrong' side so I could then make sense of what appeared to be the 'wrong side' ones on your diagram - and they're all ok.

The only alteration I have made so far is to swap "up" and "down" because I'm going to teleport the track layout and most of the arrangements to the vicinity of Dartmouth and will have a "London" connection and I think you go "up" to London.

That was the usual fashion on this bit of the GWR

If the above gets a pass mark the queries, I have are as follows(with a background period of 1956-1963)

 

1. What is the exact purpose of the Down Intermediate Starter ?

The Down Starter is there to protect No.19 points (to the cattle dock) and is typically GWR in terms of providing a protecting signal for almost every trailing point which happened to be there. So having provided the protection there for No.19 points there is then a need to protect No.12 points (to the Middle Sdg) and No.11 points (to join the single line) as No.12 is well over 100 yards in advance of No.19 and also to allow a long train to stand in advance of the Down Starter (although I'm pretty sure that would have been a very secondary consideration).

 

2. At Tavistock South the "business" end seems to be the Plymouth end as the Shunt Arm is at that end, I assume this might be because it was originally a terminus before the onward extension to Launceston. I think I will need to make the "Exeter and London" end the "business end", so can I have another Shunt Arm at that end or move the existing one there or does it not matter? I ask because I have revised my original Kingswear "light" timetable workings after a recent South Hams Holiday/field visit. I have concluded that services beyond Dartmouth would be less frequent than I originally supposed and more Exeter/Newton Abbot services will need to terminate at/return from Dartmouth.

The Shunt Ahead arm at Tavistock was probably at that end because there was where most of the longer (in train length) shunts took place. In the period that signalbox was brought into use the GWR was reasonably relaxed about providing Shunt Ahead arms and would almost certainly have provided one at the other end if there was a need for one. But also the Advanced Starter at the other end was further out so in any case provided more headroom for shunting. I suspect - but haven't seen any pics to confirm, and was alas not very much into signalling when I went to Tavvy South rather a long time ago, that the Up Advanced Starter was sited where it was for sighting reasons (or some other very logical at the time reason) which might also have led to it needing the Shunt Ahead arm.

On you station you provide what is need to do the job (or make it look more attractive - nothing wrong with signalling heresy provided it makes sense )

 

3. As there is a large discrepancy in platform lengths 480' (8 coaches) and 320'( 5 coaches) would bi-directional running/signalling be possible? If not I can live with drawing up twice or possibly not stopping at all, as this only affect one or two return through services to London/Wolverhampton, as the named services(running further in Devon now) I could use obligingly only have 5 coach portions.

Bi-directional signalling is o.k on one line and the GWR did install it a number of places on single lines although it was mainly there to allow more important services to have a 'straight run' through the pointwork.

4. I think the signal box had thirty seven levers - I can see point lever handles for some of the more remote points in the yard but how would I estimate the number actually used?

Assuming my source (George Pryer's diagram) got it right there were 37 levers in the frame with three spaces and no spares.

5. I far as I can see the signal posts at Tavistock appear to be wooden, presumably they can be teleported to Dartmouth as is (was) or could I have a mix of wooden and tubular posts?

For your period you can quite cheerfully have a mixture, by the final years most (all?) of the running signals around the station had tubular steel posts. All you need to do is sure you have the correct pattern Shunt Ahead arm for the type of post you use (some of the GWR pattern arms were still in use for most of the period you have in mind).

[cary hill]

Thanks for taking the time and trouble to compose that very comprehensive and helpful reply.

[Happy Hippo]

Have you looked at this?

 

http://www.s-r-s.org.uk/html/gwf/S976.htm

 

Which is the signalling diagram

 

Regards

 

Richard

[RailWest]

I can't say for certain (as the SRS does not have the 'lever lead' table for Tavistock (South)), but I would suggest that your Down 'Intermediate Starter' and 'Advanced Starter' are more likely to have been designated 'Inner Advanced Starter' and 'Outer Advanced Starter'.

[The Stationmaster]

I can't say for certain (as the SRS does not have the 'lever lead' table for Tavistock (South)), but I would suggest that your Down 'Intermediate Starter' and 'Advanced Starter' are more likely to have been designated 'Inner Advanced Starter' and 'Outer Advanced Starter'.

The standard (G)WR terms were 'Intermediate Advanced Starter' and 'Outer Advanced Starter' judging from what I have seen on lever leads and chats with former Reading Drawing Office staff. However the way in which the names were used seems to have varied a bit except when there was a full set - so they went Starter and Advanced Starter if there were two in advance of the 'box; Starter, Intermediate Advanced Starter, & Outer Advanced Starter or Starter, Advanced Starter & Outer Advanced Starter if there were three in advance of the 'box; and Starter, Intermediate Advanced Starter, Advanced Starter, & Outer Advanced Starter if there were four in advance of the 'box (which was a pretty rare occurrence I think).