GWR Signals and where they go?

[The Stationmaster]

Right, that's have another try - fingers crossed.

 

Subsidiary Signals are exactly what their name implies, i.e. they are subsidiary to some other sort of signal and that other sort of signal is a Stop Signal. The reason for using them is to get round the operational restrictions normally imposed by a stop signal - as will become clearer as we go into teh different types of subsidiary signal - but first we need a bit more information about stop signals. The section of line between any two successive stop signals is called a 'Signal Section' and normally only one train at a time is allowed to be in a signal section. A signal section can be a block section but signal sections also exist between each successive stop signal in Station Limits. This latter imposition can act as a considerable restraint - in say joining together portions of a train or attaching vehicles and so on. So we need a way round that if certain things are going to be possible in operating the railway and that means relaxing the governing principles - which can only be done under carefully controlled conditions (which usually turn into 'where authorised' in the words of the Rules & Regulations.

 

Once you have a relaxation permitted the next step is ensure that it is done safely and this can be by means of special handsignals but if it is to take place on a regular and/or frequent basis a fixed signal has to be provide and this is the first of our subsidiary signals - the 'Calling On' Signal. This is a small arm (illustrated below) fixed below a stop signal and when operated it calls a movement on to what might be standing in the signal section in advance of that stop signal. The arms in the pic below are in the standard style - which the GWR adopted in the 1930s - of a red arm with a wide white horizontal band running its full length; in the earlier GWR style the arm was painted red and instead of the white band it carried the letters 'CO' painted on it in white. These signals were/are most commonly found at terminus stations and large stations where portion working or shunts onto the rear of trains took place.

 

 

The second type of subsidiary we will look at is the 'Shunt Ahead' Signal for which the GWR used a fairly unique style of arm - with a large cut-out figure 'S' fixed to the front of a short red painted arm - illustrated below. The purpose of this signal was to allow shunting into the forward block when the Section Signal was sited in a way which didn't allow sufficient headroom for shunts to be made into sidings. This did not mean that it controlled facing movements into sidings - it very definitely did not, but simply that it authorised a movement to pass the Section Signal and go only as far as was necessary to gain sufficient headroom to set-back into a siding. Such a movement could also be controlled by hand signals but usually the GWR installed this type of fixed signal to control such movements because doing it that way kept a much closer control of the extent to which such shunting was permitted. Signals of this pattern could still be found into the early/mid 1960s although they were officially superseded by the standard style of subsidiary arm (as illustrated above) in the 1930s.

 

 

The final type of Subsidiary Siganl is the 'Warning Signal' and as far as I can trace there was no special - GWR signal arm for this purpose prior ro the introduction of the standard (red/white/red) arm in the inter-war years. The Warning Signal also duplicates a handsignal and, as with the other two subsidiaries, only really became established where this method of working was likely to be used extensively or frequently, and that was kept under very tight control as it involved a significant relaxation of the safety margins included in normal block signalling arrangements. When a Signalman gives the 'Line Clear' bell signal and operates his block instrument to the 'Line Clear' position for a train to enter the section from the 'box in rear he has first to have ensured that the line is clear for 440yds in advance of his Home Signal - in other words there is a safety margin (called the Clearing Point') in advance of his Home Signal. (Before any clever clogs chips in about colour light distants we are talking about the situation well before the end of the 20th century.)

 

When a Signalman is permitted to accept a train under the warning he doesn't need to have that 440yds Clearing Point, there could even be a train standing a few feet in advance of his Home Signal, so something is done to make a Driver aware that he might be approaching a signalbox and its Home Signal where there is no margin at all for any sort of braking error. The train is slowed, hard, and then the Warning Signal is cleared for it and the Driver procceds expecting to find the distant signal at caution and the Home at danger.

 

Now folk might have realised that we are using exactly the same arm for three different subsidiary purpose so how does a Driver know which is which? Simples - when the arm is lowered it reveals a special rectangular lampcase with a letter in black on the white glass ground - 'C' for Calling-On'; 'S' for Shunt Ahead; or 'W' for Warning. Sometimes the same subsidiary arm can be used for two, or even all three forms. Look more closely at these three sub arms and you will see that each is pared with an electric stencil indicator - in their case the appropriate letter will be illuminated in the indicator to show what the sub has been cleared for (I'm not absolutely certain but I believe these three signals at Severn Bridge Jcn can show either 'C' or 'W').

 

 

Next we'll be looking at Goods Line/Siding, Backing and ground shunting signals.

Edited December 6, 2011 by The Stationmaster

[dantimmy]

I think I am starting to get this now. The non shaded area is the area I will be working on with a future stretch on clear line up to a halt, with a junction after that.

 

 

If I wanted the up goods traffic to shunt into/ out of the yard is this correct? Can you have three on a post like this?

 

I haven't included the ground discs because I'll wait for your piece on them (save you typing it out twice) and for (e) would I need a stop to allow traffic to move from the goods shed/sidings to the main running line?

 

Regards

 

Dantimmy

[PWSlack]

Lose the facing crossover, and gain a headshunt from the yard first.

[beast66606]

Lose the facing crossover, and gain a headshunt from the yard first.

 

Are you looking at the same plan as me ? I can't see a facing crossover The OP has already said he doesn't have space for a head shunt.

 

Dantimmy,

 

Signals point to the left when viewed from the front.

 

Signal a and b need to be swapped, so a goes where b is and b goes where a is.

same with signal c and d

 

signal e would be a ground signal or a tall siding signal - a miniature arm on a post.

 

 

so you end up with something more like

 

 

 

Edited to move the c & d comment to where it should be

[Grovenor]

Are you looking at the same plan as me ? I can't see a facing crossover

I assume PWS is still looking at post #1

Keith

PS Why do you suggest signals © and (d) should be miniature arms?

[The Stationmaster]

I'm slightly puzzled by Beast's reference to c & d and assume a misapplication of finger to keyboard in respect of those two signals - otherwise yes, his amended positions of the signals are of course correct. We'll be looking at e (as everyone has already realised - well those who are keeping up that is ) in the next part however this will be delayed due to my attending the viewing and 'drinks & canapes' evening for this http://www.specialauctionservices.com/large/tg081211/index.html later today/this evening plus attending the sale tomorrow (if the viewing produces satisfactory reasons for attendance), it should be noted - for those who can be bothered to look at p.37 - that I shall not be bidding for any f the Lots in the range 1086 -1097 because I just don't have the room for them

[beast66606]

I'm slightly puzzled by Beast's reference to c & d and assume a misapplication of finger to keyboard in respect of those two signals

 

Not a typo, he has a distant under d ..

 

(Rereads his posting)

ahh I see, my cutting and pasting has ended up with the comment in the wrong place, now amended.

[craigwelsh]

If you were wondering why the distants moved then remember they give an indicator of what is coming in the next sections hence they are on the last post the drivers see in your section. The others will hopefully confirm i've described that correctly.

 

Thankfully distant signals were fixed at danger on lots of branches which saves having to operate them .

Edited December 7, 2011 by craigwelsh

[beast66606]

Thankfully distant signals were fixed at danger on lots of branches which saves having to operate them .

 

Caution I hope !

[The Stationmaster]

If you were wondering why the distants moved then remember they give an indicator of what is coming in the next sections hence they are on the last post the drivers see in your section. The others will hopefully confirm i've described that correctly.

 

Not quite correctly but you have picked up a point I should have made clearer in Post No. 19 when I wrote this -

But what we could realistically expect is a situation where there is a short block section and the distant signal for the next signalbox would be among the stop signals for the 'box immediately in front of us. To avoid confusion we then have a 'lower arm distant signal' where it is mounted on the same post as a stop signal but lower down the post (hence lower arm). And to get the necessary braking distance there might be a lower arm distant below several (or all) successive stop signals at a signalbox.

 

What I should have made clearer - and thank you for drawing attention to it - is that if the lower arm distant is only below one stop signal at a signalbox it will be below thehmost advanced one - the Section Signal.

 

Thankfully distant signals were fixed at danger on lots of branches which saves having to operate them .

Distant signals ceased to show a danger indication around the time of one of the 1920s re-drafting of the Rules & Regulations when the description was changed to 'caution' (which was, of course, what they had actually meant all along ).

[dantimmy]

thanks for all you help everyone, will re-read this later when I get home and make the nessicary changes etc.

 

Dantimmy

[micknich2003]

Distant signals ceased to show a danger indication around the time of one of the 1920s re-drafting of the Rules & Regulations when the description was changed to 'caution' (which was, of course, what they had actually meant all along ).

New MoT regulations of 1924. Mick Nicholson.

[Fay Singpoint]

Distant signals ceased to show a danger indication around the time of one of the 1920s re-drafting of the Rules & Regulations

Along with starting to change the lever colour as well...

F

[micknich2003]

Mick Nicholson, actualy said "New MoT regulations of 1924." Yes, indeed, the lever colours were also changed and Distants became Yellow. To keep things in perspective, prior to the change, the North British Railway, painted Distant levers Red, the same as Stop signals, and no doubt, other railways, may have done likewise. To further complicate matters, the North Eastern Rly, painted the levers working mechanical "Clearance Bars", what we would now call "Distant Yellow". Mick Nicholson.

[RailWest]

I thought that, before yellow, the more common colour for distant levers was green? Certainly the case on the LBSC as fas as I know....

[beast66606]

I thought that, before yellow, the more common colour for distant levers was green? Certainly the case on the LBSC as fas as I know....

 

It varied by company, LNWR was also green.

[micknich2003]

I'm only aware the NB painted Distant levers Red, possibly all other railways used green. Mick Nicholson.

[craigwelsh]

I'll pretend i was reading from a 1919 rulebook then . Um, yes, well at least I spurred some discussion and didn't pretend i was being definitive!

 

The provision of multiple distants makes perfect sense now you explain it in terms of braking distances and block section lengths. I think i'd always assumed only one from those nice diagrams of the perfect signalling installation you get in some books that show the one.

[The Stationmaster]

I'll pretend i was reading from a 1919 rulebook then . Um, yes, well at least I spurred some discussion and didn't pretend i was being definitive!

 

The provision of multiple distants makes perfect sense now you explain it in terms of braking distances and block section lengths. I think i'd always assumed only one from those nice diagrams of the perfect signalling installation you get in some books that show the one.

That, if nothing else, shows the need to be careful with your sources and this seems especially to apply to signalling for some reason (well actually the reason is relatively simple - quite a lot of people who have written about 'signalling', particularly some who have written about 'signalling for model railways', clearly have a rather limited understanding of the subject and this is not always going to be apparent to new comers to the subject).

 

Anyway back to dantimmy's drawings at the top of page 1 and what he called the 'Siding Signal', i.e. the one with the ring on the arm. On the GWR, with survivors lasting well into the 1960s on the WR, a ring was put on the arm to distinguish signals which applied to goods lines. They were only used on signals which were actually on goods lines and were not used on any signal reading to a goods line (unless it came from a goods line of course). A common modelling error is to use a 'ringed arm' on a signal reading to a goods line but for Western practice it is exactly that - an error. The arms ceased to be used in new work in the general massacre of GWR unique signal arms etc which came into effect in January 1950 but there seems to have been no sort of campaign replacement hence their surviving, albeit in decreasing numbers, for long after that date.

 

The goods line signal arms were generally 3 feet long and were easily distinguished from the 'Siding Signal' which used a much shorter and narrower arm but otherwise looked the same - a white painted ring on an otherwise red arm although the back of such signals was just like the goods line ones as illustrated below. I think it's far to describe siding signals as obsolescent by the 1930s although they did survive - in very small numbers in my experience - into the early part of the 1960s with one or two lasting a bit longer. One reason for this was the more general adoption of shunting signals, the familiar disc pattern, for signalling movements out of sidings and from other lines into sidings. Siding signals were at one time both to signal movements into a siding (but normally only from goods lines) and out of sidings, including some refuge sidings. So on a model railway I suspect the GWR pattern siding signal would be likely to be a comparatively rare sight.

 

Before we progress to shunting signals we'll look at the final type of signal illustrated by dantimmy - the 'Backing Signal'. Backing signals of various patterns were a not uncommon sight on a number of Pre-Group railways but after the Grouping the only Company which retained the backing signal for new work was the GWR, elsewhere they died out - in some cases quite rapidly. The backing signal - unique appearance apart, no mistaking the arm with two holes in it - is quite a difficult thing to describe in terms of its use. In fact the GWR itself was rather confused over what the signal meant and there were a number of extended debates about this over the years, the Minute Books make fascinating reading. Basically it is best to start by recognising it as a signal which indicated that a particular route had been set for a backing movement - a backing movement being one proceeding in the opposite direction to the normal direction of travel on the line to which it applied. Indeed at around the peak time of their installation (the early 20th century up to the start of the Great War) that was exactly what they did and they were commonly used where there was a potential choice of routes because unlike a shunting signal they could be used with a route indicator - and the fact that the arm was lowered was not authority for a Driver to pass the signal, he could only do that on the instruction of whoever was in charge of the movement he was about to make. In later years this changed and in many respects the meaning of a backing signal was the same as that of a shunting signal although they were also used for wrong direction train movements (but officially not passenger train movements, they needed a proper stop signal with a full length arm just like the signals we came across at the start).

 

Although no longer installed after January 1950 backing signals survived in reasonable numbers well into the 1960s - when many disappeared as a result of multiple aspect colour light signalling schemes but a few lingered on with the last going (I think) in 1985. So they are quite suitable for layouts throughout the steam era and into the diesel age.

 

This view shows the normal appearance of the back of an arm with a goods line disc (note also that in later years - probably post WWII? - the front of the arm also had the white band on red background in this arrangement as well as the ring except on most siding signals where the red band usually seemed to be absent - but then I didn't see all of them so they could well have varied)

 

 

And now something not to be confused with a Goods Line etc signal (and regrettably I only have a decent back view scanned - and it's too dark to nip out and photograph the arm languishing in my shed) is a centre pivot signal - seen here with a goods arm on the right. The centre pivot is simply a reduced length arm for use where clearances are tight.

 

 

 

Shunting signals will come next.

[micknich2003]

The provision of multiple distants makes perfect sense now you explain it in terms of braking distances and block section lengths. I think i'd always assumed only one from those nice diagrams of the perfect signalling installation you get in some books that show the one.

 

Have a look at the two attached Hull & Barnsley Rly signalling plans. As you can see "Spliting Distants" are taken to the extreme, at Springbank West the extra Distant reads on to the Shunt Neck and at Sculcoates into the Goods Yard. Note also, the H&B's wiered and wonderfull way of having the distant on a seperate doll instead of below the stop signal, as was usual practise. This only applied at signalboxes close together, elsewhere accepted convention applied. Mick Nicholson.

[dantimmy]

In regards to my layout I can have a 'siding' signal to allow traffic to leave the sidings and enter the main line. And the lines that branch off in the sidings will be controlled by ground discs??

[The Stationmaster]

In regards to my layout I can have a 'siding' signal to allow traffic to leave the sidings and enter the main line. And the lines that branch off in the sidings will be controlled by ground discs??

Probably Dan although leaving the yard could also be a ground disc - far more common than a siding signal in later years and at smaller locations. I shall be getting to ground discs/shunting signals on Tuesday (I hope) after a weekend which seems to have vanished and a potentially long day tomorrow involved with 12":1' scale 'explanations' - from which I will hopefully have recovered by Tuesday (or be lumbered with for several days of re-writing).

Edited December 11, 2011 by The Stationmaster

[dantimmy]

I look forward to your next topic

[beast66606]

In regards to my layout I can have a 'siding' signal to allow traffic to leave the sidings and enter the main line. And the lines that branch off in the sidings will be controlled by ground discs??

 

signal e would be a ground signal or a tall siding signal - a miniature arm on a post.

 

[dantimmy]

thanks beast, i do wonder where my head is sometimes lol

 

Anyway I have just spent the morning reviewing certain aspects and it would seem I have (if I do some demolition) the room to introduce a headshunt, which as said earlier can act as the trap

Edited December 13, 2011 by dantimmy