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Advice on signalling Northbridge


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Mike, I'm not sure what you mean about Q either.  There is only one route from there under the road bridge and to the fiddle yard.

 

Stephen, I think 3ft arms are fine.  I know miniature arm shunting signals were replaced or covered up by discs.

There is definitely a yellow/black ground disc at Worcester Shrub Hill as shown here (https://signalbox.org/signals/gw.htm) although I only drew it that way so that the fact it had a yellow band showed up on the diagram.

 

Version 2 below with changes:

Ground disc B replaced by 3ft arm on new bracket on C.

Bracket F removed and platform 2 now single direction.

New signal T on curve with distant and stop arms.

Signals L & M now single stop arms and new bracket S outside box for moves to platform 2/platform 1(bay).

I've left O and Q on.  I agree with Mike as per running stop signals as I'm used to seeing these around Worcester.  I put O on as this is similar to Malvern Wells where the line singles for the tunnel and the last signal in the down direction is before the single line.  So should O stay or go?

 

Signal construction of tubular posts with silver/aluminium painted posts?

Hi,

Black and Yellow shunt signal - OK - hadn't seen that one - think they were/are fairly rare

3ft arm OK

other changes OK with Q as single directional.

 

Posts - your choice of either aluminium painted tubular or white square posts, though probably best to stick with tubular. The actual bracket part of a WR (should I actually call it that - depends on how modern I suppose) bracket signal  could either be black or aluminium (pictorial evidence for both as late as 2014). Reference to GWR Signalling - Semaphore Swansong by Allen Jackson also reveals other more bizarre possibilities such as the use of LMR UQs alongside WR LQs!

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I suspect that Mike's comment about two arms on 'Q' refers to the ringed arm at the exit from the yard, in advance of which there are two routes.

 

At first glance the signal looks as if it's labelled 'O' or perhaps 'Q', but I suspect now that it's meant to be 'D' ?

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Mike,

3 things I'm not clear on:

1) Not sure how Q should be bi-directional, perhaps I've missed something.

2) Given the period being WR rather than GWR, should B not be a disc, granted perhaps elevated, as I seem to remember you saying that the  miniature arms started to be replaced in the 1930s. (Discussion on Brent/Stoke Courtnay I think)

3) Signal I - I am not sure that WR or GWR for that matter ever had black and yellow ground signals, the only difference being the light when the signal was at danger. I thought the black and yellow ones were just an aberration of preservationists/SR. Am I wrong?

 

1. Misread (by me) of the letter on the plan - should be D with two, or even three(?) arms!

 

2.  Could be either - some were replaced by discs, some were renewed as 3 ft arms on new bracket structures - really depenfsds which the OP would prefer.  The date refers to when discs started to be used in such applications - not the fact that they became manadatory; new signals with 3 ft arms reading to even dead end sidings were erected in the 1950s.

 

3. Yellow arm ground discs were introduced in new work on the WR from January 1950 and in a  number of locations gradually replaced red arm ground discs (although mainly in conjunction with alterations - in some cases the conversion was simply done with a drop of yellow paint).  Yellow on black ground discs appeared on the Western from c.the very late 1950s-very early '60s  onwards although not all yellow on white discs were ever replaced by the yellow on black version.

 

That is looking rather GW-ish. I'm not convinced that O and Q really serve any purpose unless a train or light engine could stand at them and not block the junction/single line points so something can pass behind. 

 

The other consideration is how the single line is worked. If Token, Tablet or Train Staff this will be picked up and dropped off at the box so there I don't see any benefit of them being there. The token needs to be out to clear O, so if a train stopped at Q the Fireman would have to walk forward to give up the token to free up the single line or an auxiliary token instrument provided on site. If worked by Track Circuit with Direction/Acceptance levers then there may be a benefit.

 

Would it be an advantage to put the single line points as close to the bridge/tunnel as possible and signal P to be off-scene? It may give a bit more standage at O and Q if they are provided.

 

The Western approach was to separately protect each point with a stop signal, even if they were only a couple of coach lengths apart (Ledbury is an excellent example of how this could look after points were recovered).   I think as much as anything it would have been a consequence of Western locking as it was the normal practice to apply a belt & braces approach and lock not only the signal immediately protecting a point (i.e. Q in this instance) but also the signal in rear of that (i.e. P in this instance).  As I said in this respect the Western put even the NER in the shade - and it looked even worse when they were still using repeating splitting stop signals although they had all gone by the late 1920s.

 

But overall it might be a good idea - for the reasons you give - to move the single to double connection nearer to the tunnel mouth.

 

As far as colours are concerned I have never been able to accurately date the changeover from painting tubular steel signal posts white to aluminium on the Western.  Probably sometime in the 1950s and definitely prior to 1956 (based on signals I knew to have been installed in that year never having white posts) and quite likely sometime before that (and possibly even the late 1940s?).  I am aware of one signal bearing an arm dated 1947 seemingly never having had the post painted white but I don't know when the signal was erected and the date on the arm was obviously the year of its manufacture/when it was taken into stock at Reading

Edited by The Stationmaster
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Regarding Western signal posts. Many of our boxes had a mixture of types and painting styles. Most peculiar I think would be the bracket south of Lapworth which had the flitches and dolls replaced in modern tubular form on top of an old wooden post. The dolls were silver but the main post was still white in the early 1960s.

Edited by TheSignalEngineer
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  • 5 months later...
Hi again everyone.

 

Sorry to bring back my old topic but unplanned trips to Australia (not the most unwelcome of trips!) plus Christmas have got in the way of things model railway related.

Here are my belated thoughts to the responses to my last plan and some minor changes that I'm thinking of for feedback.

 

Ringed arm "D" has got 3 possible routes (headshunt + 2 main lines) but I've gone for just the one arm.  I've based this on the ringed arm leaving the yard/carriage shed at Kidderminster SVR - this has 4 possible routes (2 platforms and 2 engine release roads) but only one arm.

 

I've added a disc in the location of the old bracket at "F" on the end of platform 2 to allow for locos to reverse towards "K" for access to the shed with another reverse past "J".

 

I was also thinking of replacing yellow disc "I" with two stacked red discs.  The top one reading back towards platform 4 with the lower one towards the steam shed.  Discs "H" and lower "I" would normally be left off allowing shunting to take place but would be reverted to danger for moves headshunt to/from platform 4.  At least in theory but I'm not expecting working discs in N gauge.

 

Your comments are again most welcome as hopefully placing an order with Stephen shortly

Edited by Ch4lkst3r
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>>>>Ringed arm "D" has got 3 possible routes (headshunt + 2 main lines) but I've gone for just the one arm.  I've based this on the ringed arm leaving the yard/carriage shed at Kidderminster SVR - this has 4 possible routes (2 platforms and 2 engine release roads) but only one arm.

 

Hmmm....you need to be careful not to assume that the practice at a current-day heritage railway will always have been the same for an older period that you are actually modelling.

 

>>> I was also thinking of replacing yellow disc "I" with two stacked red discs.  The top one reading back towards platform 4 with the lower one towards the steam shed.  Discs "H" and lower "I" would normally be left off allowing shunting to take place...

 

Not sure to what extent, if at all, the GWR/WR indulged in the practice of having conflicting signals not interlocked in such cases. Maybe Stationmaster can advise more?

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I was also thinking of replacing yellow disc "I" with two stacked red discs.  The top one reading back towards platform 4 with the lower one towards the steam shed.  Discs "H" and lower "I" would normally be left off allowing shunting to take place but would be reverted to danger for moves headshunt to/from platform 4.  At least in theory but I'm not expecting working discs in N gauge.

 

 

This technique has been used on the Bluebell Railway (not GWR I know) as our chief S&T engineer (Charles Hudson MBE) & 'Fellow' of the IRSE has an aversion to yellow disks, regarding them an unnecessary collision / derailment risk whose function can more safely be provided by omitting opposing locking in 'red' discs where necessary.

 

As others have said whether this technique was every adopted by the GWR / WR (and I suspect not) is something only the specialists in Weston region signalling practice will be able to comment on

Edited by phil-b259
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This technique has been used on the Bluebell Railway (not GWR I know) as our chief S&T engineer (Charles Hudson MBE) & 'Fellow' of the IRSE has an aversion to yellow disks, regarding them an unnecessary collision / derailment risk whose function can more safely be provided by omitting opposing locking in 'red' discs where necessary.

 

As others have said whether this technique was every adopted by the GWR / WR (and I suspect not) is something only the specialists in Weston region signalling practice will be able to comment on

 

I have no real idea whether the technique was ever adopted by the GWR/WR (but I too suspect not), but it certainly wasn't Southern practice and would often have been impossible as, at least on the ex-LSWR system, PULL and PUSH levers were typically used for opposing discs - a very robust form of interlocking indeed! Furthermore, until the late-1950s, yellow discs on the Southern were only used in colour light or power signalling areas, yellow miniature arms were used instead.

 

Perhaps the Bluebell CS&TE has forgotten the overriding principle that shunt signals only ever permit movement to the extent authorised - or does he also install screens reminding drivers of that extent.

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Perhaps I worded discs "H" and "I" wrongly but what I'm thinking of is like Signals 16A and 16B at Bridgnorth (heritage line again so maybe not correct for 60s BR(WR) - see diagram).  These are cleared for shunting onto the headshunt from the shed and left whilst shunting is taking place.  Signal 16A/B are put back to danger and signal 15 (3ft arm) is then cleared to exit shed onto running line. Also if signal 10 is cleared to access the shed (equivalent of the 3ft arm of "C" on my plan)

 

I thought that as any move into platform 4 would be a shunt move requiring reversal to leave the platform that a 3ft arm would better be replaced with a second disc.  So the top disc of "I" is signal 15 and the bottom "I" and "H" are 16B and 16A respectively.

 

Stephen, glad to hear that you think working discs would be achievable.  Not planning on lights and static weight bars would be fine.

post-25296-0-24406400-1519565065_thumb.jpg

Edited by Ch4lkst3r
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Hi again everyone.
 
Sorry to bring back my old topic but unplanned trips to Australia (not the most unwelcome of trips!) plus Christmas have got in the way of things model railway related.
Here are my belated thoughts to the responses to my last plan and some minor changes that I'm thinking of for feedback.
 
Ringed arm "D" has got 3 possible routes (headshunt + 2 main lines) but I've gone for just the one arm.  I've based this on the ringed arm leaving the yard/carriage shed at Kidderminster SVR - this has 4 possible routes (2 platforms and 2 engine release roads) but only one arm.
 
I've added a disc in the location of the old bracket at "F" on the end of platform 2 to allow for locos to reverse towards "K" for access to the shed with another reverse past "J".
 
I was also thinking of replacing yellow disc "I" with two stacked red discs.  The top one reading back towards platform 4 with the lower one towards the steam shed.  Discs "H" and lower "I" would normally be left off allowing shunting to take place but would be reverted to danger for moves headshunt to/from platform 4.  At least in theory but I'm not expecting working discs in N gauge.
 
Your comments are again most welcome as hopefully placing an order with Stephen shortly

 

 

I feel a bit of illogicality emerging here.  Signal accessing running lines with only one arm but a multiplicity of routes while a shunt disc is proposed to move from a yellow arm to two red arms.

 

Let's sort the discs out first.  No reason at all that you shouldn't have a disc with two red arms in that position if you want and it would in any case have been a disc/s or a siding signal there in any case in the days before the Western Region started using yellow arm discs.  The only thing would be that if a two arm red disc is used the opposing locking with the disc reading from the shed would probably be omitted - which then makes it no different from using a yellow arm disc but probably a bit less safe in overall terms although i'm not aware to what extent that practice was followed in GWR days.  

 

If anyone thinks yellow arm discs are 'dangerous' they really need to get a proper understanding of operating which will then indicate that they could in fact be safer than using a red disc in a situation like that because effectively the Shunter remains in full charge until it is necessary to reverse the points, and the Signalman can only do that after agreement with the Shunter.  Plus of course yellow arm discs can potentially save money in terms of operating costs compared with the red arm discs although the saving would be less with the opposing locking omitted.

 

As far as D is concerned as it gives access to running lines and I remain sure that in WR practice (and definitely so in GWR practice) a signal with a route indicator, or possibly three arms, would have been used unless a single ground disc was provided instead of a signal with a ringed arm ( I think a disc would be very unlikely in that situation in GWR days but could well appear as a renewal in later years although the amount of locking alteration need would probably mean a triple disc - up until the late 1950s or thereabouts).  Having looked at the SVR Kidderminster diagram I can see no parallel at all with signal D.  At Kidderminster the siding signal (No.23) reads to either one of two ground discs and so is effectively no more than an elevated shunting signal with no indication of route.  Unlike signal D is does not potentially signal any sort of train movement but merely shunt moves.

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Thanks for the feedback again folks.

 

I think I'll go back to a yellow disc as it was only someone elses comments (elsewhere) that made me change it.

 

I'm now thinking of replacing D with a single red disc. Only moves from here would be locos from coaling stage, turntable or TMD sidings and as we're in the 1960s I'm going with them having put one disc in to control all moves.

 

Good or bad decisions?

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If anyone thinks yellow arm discs are 'dangerous' they really need to get a proper understanding of operating which will then indicate that they could in fact be safer than using a red disc in a situation like that because effectively the Shunter remains in full charge until it is necessary to reverse the points, and the Signalman can only do that after agreement with the Shunter.  Plus of course yellow arm discs can potentially save money in terms of operating costs compared with the red arm discs although the saving would be less with the opposing locking omitted.

 

 

Which is perhaps the nub of the issue. In the case of the yellow disc the shunter is the lead person as it were and the signalman needs to get permission from the shunter that all movements have ceased before moving the points to which the yellow shunt applies. On the other hand if red discs are used hen the shunter becomes subservient to the signalman as no movement can take place till the discs are rotated to a proceed. The signaller can also bring a halt to shunting by the expedient of returning the signals to danger (though naturally liaison with the shunter would be needed where this involved putting the route back in front of a driver).

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I have no real idea whether the technique was ever adopted by the GWR/WR (but I too suspect not), but it certainly wasn't Southern practice and would often have been impossible as, at least on the ex-LSWR system, PULL and PUSH levers were typically used for opposing discs - a very robust form of interlocking indeed! Furthermore, until the late-1950s, yellow discs on the Southern were only used in colour light or power signalling areas, yellow miniature arms were used instead.

 

Perhaps the Bluebell CS&TE has forgotten the overriding principle that shunt signals only ever permit movement to the extent authorised - or does he also install screens reminding drivers of that extent.

 

I would be careful about trying to take the piss out of a long standing fellow of the IRSE, who has been our S&T engineer for over 50 years, had a long career on the 'big railway' and redesigned the Horsted interlocking from scratch.

 

While his preferred method of using red shunts with opposing locking omitted may not be prototypical, His reason is very rational, particularly in a Heritage railway setting where many signalmen have no involvement with the 'big railway' is logical - if not to everyones tastes.

 

Its all very well saying "the rule book says" but if there are practical advantages (such as not having to train up engine crews, shunters and signalmen of matters relating to yellow shunts) and in the world we live in today positive stop / go instructions are probably for the best.

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Ironically, 25 at Bridgnorth seems IMHO to be a prime candidate for a yellow disc :-)

 

Or 16A

 

While the diagram does not show whether its the case or not 16A and 16B with the opposing locking removed so as to facilitate shunting is what the Bluebell do instead of a yellow shunt at 16A.

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I would be careful about trying to take the piss out of a long standing fellow of the IRSE, who has been our S&T engineer for over 50 years, had a long career on the 'big railway' and redesigned the Horsted interlocking from scratch.

 

 

I am not really trying to "take the piss" out of him and I do understand (or at least think I understand) why preserved railways in general seem to festoon themselves with signalling which would never have existed in the historic past (and then gets copied by modellers trying to "set" their layouts in, say, the 1950s).

 

However, I seem to recollect the Bluebell setting themselves up as the "historically correct" railway. Certainly I remember quietly suggesting once upon a time that a mix of carriages in SR green and BR maroon would look much more reminiscent of the past if the MkIs were painted in BR crimson and cream, only to be abruptly told that MkIs concerned couldn't be painted in crimson and cream because they had been built after 1956.

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....and then gets copied by modellers trying to "set" their layouts in, say, the 1950s).

 

 

This is indeed a very real problem with many modellers - and indeed sort of carries over into the modern era where the urge to add signals in implausible locations continues. However those participating on this forum do an excellent resource in the form of some real experts on signalling practice back in the days of steam who can offer advise (though quite correctly most like to see the questioner having attempted a solution first - as has occurred in this thread).

 

 

:offtopic:

 

 

However, I seem to recollect the Bluebell setting themselves up as the "historically correct" railway. Certainly I remember quietly suggesting once upon a time that a mix of carriages in SR green and BR maroon would look much more reminiscent of the past if the MkIs were painted in BR crimson and cream, only to be abruptly told that MkIs concerned couldn't be painted in crimson and cream because they had been built after 1956.

 

That "historically correct" ethos has been on the wane for a few years now as reality bites. Having been in a pretty desperate way rolling stock wise thanks to the need to push virtually all monies into clearing the tip / getting back to East Grinstead we have a number of privately owned C&C Mk1s on the railway which can be used for normal traffic in lue of rent. As a result a couple of the railways own Mk1s have also received C&C even if its not authentic to match. Similarly the use of the Westinghouse L frame at Kingscote is hardly 'typical' of a wayside country station....

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I would be careful about trying to take the piss out of a long standing fellow of the IRSE, who has been our S&T engineer for over 50 years, had a long career on the 'big railway' and redesigned the Horsted interlocking from scratch.

 

While his preferred method of using red shunts with opposing locking omitted may not be prototypical, His reason is very rational, particularly in a Heritage railway setting where many signalmen have no involvement with the 'big railway' is logical - if not to everyones tastes.

 

Its all very well saying "the rule book says" but if there are practical advantages (such as not having to train up engine crews, shunters and signalmen of matters relating to yellow shunts) and in the world we live in today positive stop / go instructions are probably for the best.

 

Thing is Phil you have to train them anyway so adding yellow shunts is a very minor addition - far less minor than certain other things that are far more critical to their safety.  The big advantage of yellow discs is that they leave a single person, the Shunter, in charge and he controls everything until there's any need to move through the point the yellow disc refers to in its reverse position - then he asks to 'ask out' or the Signalman has to 'ask in'.  In many respects in this instance signal engineering should be supplying equipment to match a a decision made by the operator and not the other way round (as seems to happen on some heritage type railways - and I'm not talking about the Bluebell in that context).

Or 16A

 

While the diagram does not show whether its the case or not 16A and 16B with the opposing locking removed so as to facilitate shunting is what the Bluebell do instead of a yellow shunt at 16A.

 

16A couldn't be yellow if 15 remains as it would then involve passing a signal at danger.   As it stands it seems that a single lever works 16A and 16B - hence their numbering.  An alternative would have been to make 15 a yellow disc and have lever 16 working what is currently 16B.  But whoever planned the signalling decided, for whatever reason, not to do the job that way (probably because 15 reads to the running line and is used to signal engines heading off into the section?)

 

There are however some other peculiarities at Bridgnorth such as 23 & 24 having C/O subs but 15 not having one when one might have expected such moves would have been just as likely from it as from the platform lines.

 

Edit to correct geographical typo

Edited by The Stationmaster
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There are however some other peculiarities at Bewdley such as 23 & 24 having C/O subs but 15 not having one when one might have expected such moves would have been just as likely from it as from the platform lines.

I wondered why they had subs at all, or else just shunt discs if really necessary?

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I wondered why they had subs at all, or else just shunt discs if really necessary?

 

The use of C/Os implies they are intending to signal expecting movements into the occupied signal section between 23/24 and the advance Starter No.22.  Quite why they would do that I'm not really sure although it might conceivably save a few minutes with light engine movements and the two platform starting signals are a reasonable distance from the signalbox so a handsignal to pass either 23 or 24 at danger would not be particularly straightforward or easy to see. 

 

But that apart I can see no reason at all for the C/O arms on those signals.  And equally no need for shunt discs because all they would do is the same as the running arm (or a C/O arm reading into an occupied signal section).

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