Two aspect colour light signal question.

[Neil]

In the UK would two aspect signals show either red/green or yellow/green? Would there be circumstances where a signal would show red/yellow, the equivalent of a home with a fixed distant arm?

[anroar53]

Signals into Terminal stations are usually Red/Yellow, plus subsidiary. Changed in the mid 1970s from Red/Green.

Some Low speed lines also have Red/Yellow only. Before re-signalling in the Hastings area the Signal on the Down Platform at St. Leonards Warrior Square only displayed Red/Yellow, even if the Home signal was clear at the other end of the Tunnel running into Hastings.

[russ p]

The lines round tinsley yard only showed red and yellow 

[The Stationmaster]

The answer depends very much on where and when.  

 

For instance on our branch the terminus acquired colour light signalling in 1963 (in connection with a test of a new type of interlocking). The 'home signal' exhibited either a red or a single yellow main aspect. later in the 1960s it was altered from the WR standard to the national standard and showed either red or green and even later than that - when the national stamndard was changed - it reverted to showing either red or single yellow.  Fortunately it always - in those days - boasted a three lens head so alteration was very simple. In its later years the three lens head was replaced by a two lens head;  it continued to show red or yellow for the rest of its life, 

 

But then comes a very amusing situation.  The signal which replaced it - in the 21st century - shows either a red or green aspect although it is somewhat further from the stop blocks at the terminus - about 5 miles further away.  But there is now an (unproved) retro-reflective distant board more or less on the site of the previous red/yellow signal.  And the branch terminus has in effect, after over 50 years,  reacquired a semaphore fixed distant in place of the colour light fixed distant it had during the intervening period.  Strange old world isn't it

[Swindon 123]

21 hours ago, anroar53 said:

Signals into Terminal stations are usually Red/Yellow, plus subsidiary. Changed in the mid 1970s from Red/Green.

Some Low speed lines also have Red/Yellow only. Before re-signalling in the Hastings area the Signal on the Down Platform at St. Leonards Warrior Square only displayed Red/Yellow, even if the Home signal was clear at the other end of the Tunnel running into Hastings.

As was, and probably still is at Chingford, as seen here in my photo taken back in October 1983.

 

The other scenario mentioned was were a fixed distant was involved, as in this photo of Shrewsbury Severn Bridge Junction SB's Up Home signal at English  Bridge junction.

 

Also on the approach to Harlescott on the Crewe to Shrewsbury line, the 1st Up home signal was changed from a semaphore to a colour light (before the latest scheme),  it could only show, Red, single yellow, or double yellow, but never a green.

 

Paul J.

 

[Neil]

Many thanks for all the replies. I now know a good deal more than I did a few days ago. Hopefully you'll see the installation resulting from my question on my layout thread in the none too distant future.

[Pandora]

The type of working you describe, a form of distant/home semaphore but with colour lights,    the distant colour light will have a letter R after the signal number eg T123R, and the identity plate will show  a triangle synbol ,  this means the signal head CANNOT show a Red aspect,  only a proceed aspect,  (and  usually there  isn't a signal post telephone on the signal). Therfore the signal will show Green or YEllow, but not both at the same time, when Yellow it is telling  the driver the stop signal ahed   is currently showing a RED and the driver should control his speed accordingly, (at caution)

 

 

 

Additionall

In 4 aspect schemes,  the driver will see a signalleed sequence G - YY- Y- R,  but think of a terminus  station platform,  the red light on the buffer stop is the fixed stop signal (the R) ,  the signal into the platform cannot show a green or 2 yellows,  it would be out of sequence with G-YY-Y-R,  therefore the signal into the platform will be 2 aspect signal head , , without a  G or YY,  Only being able to show Y or R ( or R plus call on  subsidiary if platform is permissive working)

Edited March 7, 2020 by Pandora

[101]

4 hours ago, Pandora said:

 

Additionall

In 4 aspect schemes,  the driver will see a signalleed sequence G - YY- Y- R,  but think of a terminus  station platform,  the red light on the buffer stop is the fixed stop signal (the R) ,  the signal into the platform cannot show a green or 2 yellows,  it would be out of sequence with G-YY-Y-R,  therefore the signal into the platform will be 2 aspect signal head , , without a  G or YY,  Only being able to show Y or R ( or R plus call on  subsidiary if platform is permissive working)

 

You used to be able to get a green signal straight into a terminal platform, can't remember when that changed - possibly after the Paddington sleeper incident?

[Nearholmer]

And, the classic London Underground system has subtle differences from main-line practice http://www.trainweb.org/tubeprune/signalling3.htm

 

The Watford dc lines used to have a strange signalling system that I never quite understood, which I think was effectively two aspect, but with a stop and a repeater/distant on each post, yielding three-aspects (not including red over green or red over yellow) ...... if anyone knows for certain, please elucidate.

Edited March 7, 2020 by Nearholmer

[beast66606]

40 minutes ago, 101 said:

possibly after the Paddington sleeper incident?

 

Moorgate I think

[Nearholmer]

Found this explanation of the Watford dc lines signalling http://www.railsigns.uk/info/watnew1/watnew1.html

 

Having skimmed it, I’m still almost as confused by it as when I used to see it for real!

[Pandora]

3 hours ago, 101 said:

 

You used to be able to get a green signal straight into a terminal platform, can't remember when that changed - possibly after the Paddington sleeper incident?

Wierd arrangement to have a Green before the buffer stops,   when  all you need the signal to have is the  Yellow lens  in front of the bulb. I don't suppose it would bother the  Old Guard on the Footplate too much

[TheSignalEngineer]

Don't forget amongst all of this is that you don't have a green to a red when signals are only two aspect. 

[Edwin_m]

3 hours ago, Pandora said:

Wierd arrangement to have a Green before the buffer stops,   when  all you need the signal to have is the  Yellow lens  in front of the bulb. I don't suppose it would bother the  Old Guard on the Footplate too much

I think many years ago some termini used yellow (possibly on a semaphore distant not a colour light) for a route into an occupied platform and green for route clear to stops.  

[TheSignalEngineer]

1 minute ago, Edwin_m said:

I think many years ago some termini used yellow (possibly on a semaphore distant not a colour light) for a route into an occupied platform and green for route clear to stops.  

Some early colour light schemes used Green for clear platforms and a Delayed Yellow for occupied platforms

[Nearholmer]

34 minutes ago, Edwin_m said:

I think many years ago some termini used yellow (possibly on a semaphore distant not a colour light) for a route into an occupied platform and green for route clear to stops.

 

Yes, the LBSCR, and I think possibly other re-SR lines used that approach, a home over a distant as the last signal entering a terminus, before 'calling on' signals were invented I guess.

 

One possible difference between semaphore practice and TCB colour-light is that signalmen would hold the home 'on' until they could see that a train was well under control, before clearing it to allow that train to run towards the stops at a terminus or towards an 'on' starter signal at a station. I've even seen a signalman 'waggle' a stop semaphore before pulling it off properly, as a way of alerting a driver to the fact the next signal, an advance starter, was still 'on'.

 

 

Edited March 7, 2020 by Nearholmer

[beast66606]

Birkenhead Woodside had a working semaphore distant - obviosuly for the approach to the terminus, even in BR days.

[NIK]

Hi,

 

Red/Yellow: the last signal on the Lewes to Brighton line before Brighton Station (terminus) I recall ~1980.

 

Back along the line north of Eastbourne was/is a sprung point on the junction between Hastings/Eastbourne and Eastbourne/Lewes lines (reversal at Eastbourne).

 

 

Regards

 

Nick

[Mark Saunders]

14 hours ago, Pandora said:

Wierd arrangement to have a Green before the buffer stops,   when  all you need the signal to have is the  Yellow lens  in front of the bulb. I don't suppose it would bother the  Old Guard on the Footplate too much

 

You are judging yesterday by the norms of today!

 

The idea of a green to a clear signal does not apply when you think in semaphore signalling as the only yellow aspect was in a distant that was On. Worked on semaphore terms these would only be cleared when the train was at a stand or nearly to allow the train entry.

 

 

[TheSignalEngineer]

Clearing semaphore Home signal with the train at or nearly at a stand had the same meaning as a delayed yellow on a colour light. On a through line the track is clear to the next signal but not necessarily beyond it so proceed with caution, being prepared to stop at the next signal or stop at the platform as appropriate.

Various local rules applied, such as one I was involved where a through station with a signal on a steep gradient on the approach had a free yellow as it was difficult to restart a heavy train there. On another line trains were banked through a tunnel with the Home signal just outside the exit. I altered the controls so it could be cleared as soon as the train had passed the distant following an incident when the driver braked for the Home and the banker driver still out of sight in the tunnel kept pushing. Big pile of wagons in the cutting at the tunnel mouth. 

These local conditions were listed in the Sectional Appendix as locations exempt from Rule 39A.

[The Stationmaster]

17 hours ago, Nearholmer said:

Found this explanation of the Watford dc lines signalling http://www.railsigns.uk/info/watnew1/watnew1.html

 

Having skimmed it, I’m still almost as confused by it as when I used to see it for real!

Going wildly OT but just to keep you on your toes you should try the city loop signalling in Sydney NSW where you can get double red and double green aspects among a good few more.  It is the only colour light signalling installation I know (but there are no doubt others?) where a colour light 'distant signal' equivalent is supremely old-fashioned and uses red for the caution aspect.  Just to confuse things on the short loop sections the stop part of the signal can also show a yellow aspect.  

 

It's a very clever aspect sequence once you understand it but very odd when you don't but it does the job of running peak hour trains on very tight headways with minimal delays.

[The Stationmaster]

12 hours ago, TheSignalEngineer said:

Some early colour light schemes used Green for clear platforms and a Delayed Yellow for occupied platforms

There were also some early schemes where a green was given into an empty longer platform and a yellow into shorter platforms (as well as into partially occupied longer platforms).

[WillCav]

Some yellow/red signals before terminii were 3 or 4 aspect heads with other aspects blanked out. Possibly for economy so only one head type needed ordering? 

 

Also, Dorman LED units are only available as RYG and you use the same head for 3 aspect, RY  RG, YG, fixed red etc. And 2 units double stacked for 4 aspect. (Other manufacturers are available, I think the same is true for the VMS type).

 

Distant signals on modern schemes are not generally numbered ...R now, they are just given another unique number.

 

Will

 

[5BarVT]

21 hours ago, TheSignalEngineer said:

Don't forget amongst all of this is that you don't have a green to a red when signals are only two aspect. 

Just to confuse: except on Merseyrail Loop line (I believe) where it is more akin to LU stop on sight with train stop protection.

Paul.

[beast66606]

34 minutes ago, 5BarVT said:

Just to confuse: except on Merseyrail Loop line (I believe) where it is more akin to LU stop on sight with train stop protection.

 

and 2 x  2-aspect (and lens) heads - a stop/go and a repeater for the next stop/go rather than 3-aspect.