GWR semaphore signal spectacle colours

[kitpw]

It sounds like a simple question but I doubt there's a simple answer!  Stop signals show a red light when 'on' and a green light when 'off'.  Distant signals show yellow when 'on' and green when 'off'.  I read somewhere that subsidiary signals - such as backing signals, shunt signals and goods loop to main starters show a white light when 'on' and green when 'off': except that (colour) photos which I've found on the web seem to show red regardless of the signal type.  Can anyone clarify what would have been "true" in 1927 on the GWR?

 

Kit PW

7mm scale layout: Swan Hill - https://www.rmweb.co.uk/community/index.php?/blogs/blog/2502-swan-hill/

 

[The Stationmaster]

The use of white light in things like backing signals and sifding signals tended to be rather variable but generally at that time they would have complied with the standard (introduced in the early 1890s) applicable to the use of white light in independent ground discs.  That standard basically meant that if, when standing normal, the points the signal read through led towards an in dependent ground etc signal (but not a running signal) that had a red light then the independent ground disc would have a white light when at danger.

 

However there were changes in respect of backing signals in particular as their meaning when 'off' was subtly altered over the years although in summary they effectively ended up meaning more or less  the same as an independent ground disc.

[kitpw]

Mike, thanks for the response - I suspected that there must variability as the books I have on signals (Vaughan and, on modelling signals, Peter Squibb's book) seem to show red on all signals as do all the signals shown in colour that I could find on the web. Vaughan, however, includes a facsimile of the 1936 Appendix to the Rule Book which calls for "white or red" lights on backing, goods loop line and siding signals but without explanation of what the parameters are for choosing one or the other.  As far as present modelling is concerned, I'll stay with red for now - it's probably one of the easier things to change if, in the future, it looks like I've transgressed!

 

Kit PW

[Compound2632]

On 14/12/2020 at 12:09, kitpw said:

Can anyone clarify what would have been "true" in 1927 on the GWR?

 

In 1925 the MoT required the adoption yellow with a black chevron for distant signal arms together with yellow spectacles. Prior to this on many lines distant arms were red and only distinguished by the fishtail. I very much doubt that even on the Great Western the change would have been anywhere near complete by 1927. This article by L.G. Warburton shows that the LMS didn't really get going on making the change until 1929. (White aspects for calling-on arms are also mentioned there.)

 

The "green" glass in signal spectacles was usually blue. This filtered the yellow light of the oil lamp to give a green light.

 

For the GWR and yellow distants, calling @Miss Prism, @Stationmaster...

[ikcdab]

The old rhyme...

White is right, red is wrong,

Green means slowly go along....

[kitpw]

Thanks Compound2632 - the Warburton's article certainly clarifies the lamp colour requirements and changes through time.  I had understood the change to yellow distants in the mid 20s but distants probably won't appear on 'Swan Hill' so I'm relieved of the burden of wondering whether they should be red or yellow!   It's really the non-running signals which raised a question - the "red or white" of the 1936 Appendix to the Rule Book doesn't explain any more than that but the assumption must be that both existed. I read somewhere (but haven't been able to retrieve the reference from memory) that concern that there were too many red lights showing, causing real or potential confusion to drivers, and, in consequence, some subsidiary signals were changed to white.  Looking at photos of signals - and they need to be in colour - I can only find red spectacle glass regardless of signal type:  this also seems to be true of model signals.  At the moment, I'm installing red glass: it can be changed!  In reality, I've put in clear and used Marabu glass paint - cherry red and blue - to obtain the colour (along with testing quite a few LED types to get the colour shift to green) .  I ought to post on 'Swan Hill' about signals as they have now started to appear on the layout.

 

Thanks ikcdab.  I grew up with such rymes -  but nautical rather than railway.  Tea was quite often accompanied by "If to port a light you see, go below and wet the tea".  I think the're called 'mnemonics' - they seem to come to mind very easily, even at a distance of many years.

 

Kit PW

 

A 1920s 7mm terminus layout: Swan Hill - https://www.rmweb.co.uk/community/index.php?/blogs/blog/2502-swan-hill/

 

[Miss Prism]

Not sure when yellow started to be used for distant spectacles on the GWR. Probably c 1910. Before that I get the impression that no glass was fitted, and the yellow of the oil lamp was good enough. Distant arms were red up to c 1924, when they started to be changed to yellow, a process that was substantially complete by c 1927.

 

[Trainshed Terry]

4 hours ago, Compound2632 said:

The "green" glass in signal spectacles was usually blue. This filtered the yellow light of the oil lamp to give a green light

 

You beating me to it.

 

Terry.

[The Stationmaster]

3 hours ago, Compound2632 said:

 

In 1925 the MoT required the adoption yellow with a black chevron for distant signal arms together with yellow spectacles. Prior to this on many lines distant arms were red and only distinguished by the fishtail. I very much doubt that even on the Great Western the change would have been anywhere near complete by 1927. This article by L.G. Warburton shows that the LMS didn't really get going on making the change until 1929. (White aspects for calling-on arms are also mentioned there.)

 

The "green" glass in signal spectacles was usually blue. This filtered the yellow light of the oil lamp to give a green light.

 

For the GWR and yellow distants, calling @Miss Prism, @Stationmaster...

As I read it the OP's question didn't really involve distant signals as he was particularly concerned about the GWR's use of white lights, in stead of red, in various stop signals.

 

According to an article in a contemporaneous GW staff magazine the changeover of GWR distant signals to yellow arms & lights was completed in 1929.  However I have seen somewhere or other a photo claimed to be dated 1931 which showed a distant signal with a red arm so the 1929 claim might possibly have referred (without saying so) to main line routes only or somebody had misdated the photo.  

 

Incidentally the change to yellow arms and lights was proposed by the IRSE Committee constituted in 1921 to review signal aspects.  At least one Railway had started doing it before the Great War but the IRSE Committee came out with yellow as a consistent caution indication for two position and three position (which already used it in that way) semaphore signals and colour light signals.  The RCH standard colour for levers working distant signal was changed from green to yellow at the same time.  Thus some Companies were already changing distant signals to yellow arms and lights before the MoT requirement emerged

 

27 minutes ago, Miss Prism said:

Not sure when yellow started to be used for distant spectacles on the GWR. Probably c 1910. Before that I get the impression that no glass was fitted, and the yellow of the oil lamp was good enough. Distant arms were red up to c 1924, when they started to be changed to yellow, a process that was substantially complete by c 1927.

 

The GWR 1920 General appendix states that distant signals fixed at caution have a lamp with a red lens.  Axccording to one minute book in 1915 the GWR was looking into a suggestion that some sort of mark be used to enable the light shown by distant signals at night to be distinguished from that shown by stop signals.  Presumably something akin to a Coligny Welch indicator was in mind although I doubt the GWR would have wished to pay for those!

 

Incidentally in the 1920 GA the caution light in 3 position semaphores was described as 'orange'.

 

3 hours ago, ikcdab said:

The old rhyme...

White is right, red is wrong,

Green means slowly go along....

Which of course of goes back to much earlier times when it was was in respect of running signals.    

 

But it has really long applied - and of course still does - to handsignals given at night where white is indeed 'right' (i.e. go at normal shunting speed), red means 'stop' or don't move, and green means 'slow down'.  Hence looking out on your side when shunting you might say to the driver 'green light mate' at which he would reduce speed and you might equally use the term in daylight (many did) because it was the simplest way of  saying slow down.

 

Incidentally going back to the OP's question white light ground discs and backing signals lasted in considerable numbers well in to the 1960s and I'm sure that some examples were around much later although they disappeared as layouts were rationalised.

[Compound2632]

48 minutes ago, The Stationmaster said:

As I read it the OP's question didn't really involve distant signals 

 

True but he mentioned them and as the date he mentioned is one of change I thought I'd throw it in just in case. Which anyway has flushed out information on the GW's progress - evidently ahead of the LMS, although of course the latter had many more route miles of main lines, much of which was more densely signalled (shorter sections) than the GW main lines.

 

As he said, on most model railways distants are off-scene - the exception being if one is modelling an line with short sections and slotted distants.

[kitpw]

It's curious that the hand signal colour light sequence of white (ok to move), green (slow, caution) and red (stop) should differ from the signal sequence of green (or sometimes white), then yellow for caution and then red.  I guess because hand signals are not (often or ever) modelled, I don't have much of a clue about them, in what circumstances they were/are used and what rules apply. 

 

Kit PW

 

 

[Compound2632]

3 minutes ago, kitpw said:

It's curious that the hand signal colour light sequence of white (ok to move), green (slow, caution) and red (stop) should differ from the signal sequence of green (or sometimes white), then yellow for caution and then red. 

 

Presumably because hand lamp signals date back to the earliest days - when for fixed signals, green was caution (arm at 45 deg) and white was all clear (arm vanished into slot in post) - whereas the yellow caution aspect is a newfangled 20th century invention.

[Nick Holliday]

Although not specific to the GWR, these snippets might be of interest/relevance.

These come from a 1912 paper on signalling:

and

From a later, 1935, paper

Note the reference to "in recent years" although the Coligny-Welch fish-tail light had been around for over twenty years!

 

[Michael Hodgson]

6 hours ago, The Stationmaster said:

The GWR 1920 General appendix states that distant signals fixed at caution have a lamp with a red lens.  

 

That doesn't sound quite correct.  When Distant signals were red rather than yellow, they were said to be at Danger rather than at Caution.  If the Appendix uses that terminology, they must have been anticipating the colour change which would have been under discussion.

 

They would still have been red in 1920, the change was a few years later.  This would have applied to worked distants as well as fixed ones.  However the GWR at that date were using orange lights for Caution on their 3-position semaphores in the Paddington area. 

[The Stationmaster]

15 hours ago, Michael Hodgson said:

 

That doesn't sound quite correct.  When Distant signals were red rather than yellow, they were said to be at Danger rather than at Caution.  If the Appendix uses that terminology, they must have been anticipating the colour change which would have been under discussion.

 

They would still have been red in 1920, the change was a few years later.  This would have applied to worked distants as well as fixed ones.  However the GWR at that date were using orange lights for Caution on their 3-position semaphores in the Paddington area. 

Sorry I used the word caution, force of long established habit.  The GWR GA simply described the fixed distant light as having a red lens.   As for the date that was included to amplify and correct something stated by Miss Prism - some Companies (I think perhaps only on the London Underground lines as the Metropolitan was one of them) were of course already using yellow for distant signal ams and lights prior to the 1921 IRSE committee's recommendations.

 

Interestingly the GWR 1936 GA does not show a colour in the caution aspect for the three position semaphores although it does show red in the danger position and green in the clear position illustrations.  The quite well known 3 position semaphore at Paddington had almost certainly gone by then as it was replaced by a 3 aspect colour light (I think on the same post) in approximately the early 1930s (maybe even a little earlier than that?) and that signal in turn was swept away but the 1930s major alterations to the Paddington track layout and the provision of the new power signal boxes at Paddington and Westbourne Bridge.  

 

The other, much more extensive, GWR 3 position semaphore installation - which I think was unique in Britain in using automatic 3 position semaphores - lasted until just after WWII (1947 I think without checking the date) although by then it was no longer used by timetabled  GWR services.

 

20 hours ago, Compound2632 said:

 

Presumably because hand lamp signals date back to the earliest days - when for fixed signals, green was caution (arm at 45 deg) and white was all clear (arm vanished into slot in post) - whereas the yellow caution aspect is a newfangled 20th century invention.

Exactly so.  I suspect the reason for never changing handsignal colours to the new standard for running signal lights was as much as anything down to simply not considering it justified and maybe somebody even thought about the cost of altering or renewing thousands of hand lamps used by Shunters and Guards.

 

Oddly when I was on the 1985 Rule Book review working party we did very briefly discuss the possibility of changing the green light shunting handsignal to a yellow light but decided it wasn't worth doing because everyone on the ground understood what the handsignals meant and were using them all the time so it would have been little more than change for the sake of change.    The earlier change to the audible handsignals (using a whistle or klaxon) had made a lot more sense because altering to one blast for stop (from the previous 3 for stop) made a lot more sense because the signal to stop could no longer be confused with other signals and it brought  the shunting audible signals into line with the DMU buzzer code.

[Michael Hodgson]

According to the Railsigns site, the BoT required signals to show only red or green lights in 1892 (for new works) and the following year the RCH recommended that existing signals be changed.  They also say the GCR changed to yellow lenses for distants at caution in 1916 despite the BoT, and the arms to yellow in 1918.  They also have the GWR Ealing & Shepherd's Bush line with automatic 3-position pointed arms in 1917 with orange for caution, and the Barry Railway using experimental orange arms and lamps in 1921.

 

 

If you had changed the green hand lamp to yellow for shunting, wouldn't the yellow and white GPL have remained something of an anomaly?  Yellow = passable if the points are set one way, stop if they're the other.  OK, not dangerous as the signalman shouldn't be reversing the siding exit points unless he also intends to clear the signal.  I think the change in the colour of pivot lights from white was more in keeping with the original late Victorian need to move away from white on running signals. 

 

The big risk with any changes in the meaning of colours etc is possible confuston during the transition period and ingrained habits.

[tomparryharry]

Just a bit of an aside, but the green colour on signal lenses  is made from copper and, I think, acetic acid.  The verdigris is used in the glass-making process. There is a Board of Trade requirement on the pigment used to get the correct shade. 

[Compound2632]

14 minutes ago, tomparryharry said:

Just a bit of an aside, but the green colour on signal lenses  is made from copper and, I think, acetic acid.  The verdigris is used in the glass-making process. There is a Board of Trade requirement on the pigment used to get the correct shade. 

 

But they're blue not green.

[tomparryharry]

7 minutes ago, Compound2632 said:

 

But they're blue not green.

 Run a yellow-tinted oil lamp, and see what you get......

[Compound2632]

21 minutes ago, tomparryharry said:

 Run a yellow-tinted oil lamp, and see what you get......

 

Green light using a blue filter. 

[Michael Hodgson]

59 minutes ago, tomparryharry said:

Just a bit of an aside, but the green colour on signal lenses  is made from copper and, I think, acetic acid.  The verdigris is used in the glass-making process. There is a Board of Trade requirement on the pigment used to get the correct shade. 

 

I don't think it's verdigris nowadays with these modern LED lamps. 

Their colours don't degrade over time or change when the lens  develops an accumulation of algae, bird dung etc.

[tomparryharry]

2 hours ago, Michael Hodgson said:

 

I don't think it's verdigris nowadays with these modern LED lamps. 

Their colours don't degrade over time or change when the lens  develops an accumulation of algae, bird dung etc.

 

Yes, you very likely correct. The lampmen would clear the lens if it needed a wipe. Please remember however, that I replied to the topic, not leds.

[The Stationmaster]

Incidentally the GWR controlled 3 position signals, and not just the automatic signals, were all capable of showing the orange caution aspect.

 

GPLs went through two chjanges over the yrears.  The earliest versions - used first at Leeds in 1937 - showed only white lights for some applications but a white pivot light with a red 'on' indication when used to protect trap points and derailers.  Red (or yellow) subsequently became universal for all GPLs.  The next change, doing away with white for the pivot light.  was made in order to bring GPLs into line with the new standard for Limit of Shunt signals.

 

The yellow arm & light ground disc (which the GWR never used of course) or yellow light GPL wouldn't clash any more with a yellow shunting hand signal than a white light ground disc clashed with a white handsignal or a green proceed aspect in a ground signal clashed with a green handsignal.  The fixed signal aspects have always had different meanings from those of the handsignals.

[kitpw]

A little "off topic" but as the OP, perhaps permitted?  I noticed in the biograph film showing the approach to Windsor from a train recently referred to in the "More Pre-Grouping Wagons in 4mm - the D299 appreciation thread" on RMweb (see https://player.bfi.org.uk/free/film/watch-the-brilliant-biograph-2020-online from about 41) a ringed distant arm - it looks like it's a working distant - on the steeply graded exit from the goods yard spur leading up to the station.  The film shows a very nice collection of signals, including 4 backing signals, one above the other on a single post.

 

Kit PW

Swan Hill - https://www.rmweb.co.uk/community/index.php?/blogs/blog/2502-swan-hill/