Colour Light Signals - Light Order

[Efini92]

There used to be a signal on the (now removed) Down Slow approaching Bolton that could only show a maximum of Double Yellow; but in that case was a 4-aspect head with the green aspect blanked out (I presume was produced with the other 4 aspect heads in the area), so still giving the correct spacing between the Yellows.

Where was that? I don’t recall Bolton having slow lines

 

[edwin_m]

Where was that? I don’t recall Bolton having slow lines

It was four track from somewhere north of Moses Gate through to Lostock Junction at one time.

 

[Efini92]

It was four track from somewhere north of Moses Gate through to Lostock Junction at one time.

They had goods through the station and passenger loops from burnden to Moses gate. Don’t recall them ever being called slow lines.

 

[Ianno87]

They had goods through the station and passenger loops from burnden to Moses gate. Don’t recall them ever being called slow lines.

2005 Quail Maps shows them as the Up and Down Passenger Loops.

Where was that? I don’t recall Bolton having slow lines

Mis-remembering; they were the Up and Down Passenger loops between Moses Gate and Bolton.

 

[21C101]

Incorrect on the splitting distant. If the junction signal is at danger, only one head will be lit. Both heads only illuminate when there is a route set through the junction, whether that be diverging or straight ahead.

Closest you'll get to 'horizantal' yellows is if the least restrictive route is showing Double Yellow.

That is the case now. Pre "feathers" multi headed monsters had red lights on all the heads with a head for each permissible route.

 

[Annetts key]

Maybe it’s important to point out that a modern colour light signal, that can only show red/green, can precede another signal with a red/(yellow)/(green) aspect under certain circumstances. It depends on which signals are protecting the block section (be it track circuit block or any other type). The block section limits (plus other details) are used to form the aspect sequence diagram.

For example, prior to the re-control of the Westerleigh to Swindon line from Bristol Panel to TVSC, signal UB103 at Chipping Sodbury tunnel was not a section signal. It was in the middle of the axle counter section. It normally showed green regardless of where trains were. The controlled signals in rear B119 (up Badminton) and B417 (goods loop) hence although three aspect colour light heads, had their middle (yellow) aspects blanked out (one had a metal plate painted black, I can’t remember what the other one had). The signal ahead (beyond) UB103 was UB99R (a two aspect colour light repeater, with yellow and green aspects), followed by UB99 (three aspect colour light).

Hence the block section was between B119/B417 and UB99 signals. UB103 was retained after axle counters were installed (previously track circuitsso that if the tell tale wire was broken or the signaller operated the Chipping Sodbury tunnel emergency switch, it would show a red aspect.

A different situation can arise on branch lines where the service level is low. In order to keep costs low or for other operational reasons, including minimum alterations due to layout changes or changed requirements. For example signals may be required to be provided, complete with red/green aspects, but which are not treated as section block signals. The line between Avonmouth station and Severn Beach is an example.

Trains travelling from Avonmouth station towards Hallen Marsh junction encounter SA7 signal (provided with red and green aspects) then SA47 (red/green aspects). SA47 protects the points at Holemouth junction. If SA47 is routed to Severn Beach, this is the last main aspect colour light signal. Leaving aside the special GPL SA627 (which normally shows two white lights), there is a fixed distance board on approach to Severn Beach station and the stop blocks. But if SA47 is routed over to the Up Avonmouth Dock line towards Filton West, SA47 signal requires SA37 signal to be showing a proceed aspect before it will clear. SA7 signal in turn requires that SA47 is showing a green aspect...

Here, SA7 is the block section signal. The line between SA47 and Severn Beach being a One Train Working (OTW) section). For the route to the Up Avonmouth Dock line, SA37 is the next block section signal.

 

[Ianno87]

Maybe it’s important to point out that a modern colour light signal, that can only show red/green, can precede another signal with a red/(yellow)/(green) aspect under certain circumstances. It depends on which signals are protecting the block section (be it track circuit block or any other type). The block section limits (plus other details) are used to form the aspect sequence diagram.

For example, prior to the re-control of the Westerleigh to Swindon line from Bristol Panel to TVSC, signal UB103 at Chipping Sodbury tunnel was not a section signal. It was in the middle of the axle counter section. It normally showed green regardless of where trains were. The controlled signals in rear B119 (up Badminton) and B417 (goods loop) hence although three aspect colour light heads, had their middle (yellow) aspects blanked out (one had a metal plate painted black, I can’t remember what the other one had). The signal ahead (beyond) UB103 was UB99R (a two aspect colour light repeater, with yellow and green aspects), followed by UB99 (three aspect colour light).

Hence the block section was between B119/B417 and UB99 signals. UB103 was retained after axle counters were installed (previously track circuitsso that if the tell tale wire was broken or the signaller operated the Chipping Sodbury tunnel emergency switch, it would show a red aspect.

A different situation can arise on branch lines where the service level is low. In order to keep costs low or for other operational reasons, including minimum alterations due to layout changes or changed requirements. For example signals may be required to be provided, complete with red/green aspects, but which are not treated as section block signals. The line between Avonmouth station and Severn Beach is an example.

Trains travelling from Avonmouth station towards Hallen Marsh junction encounter SA7 signal (provided with red and green aspects) then SA47 (red/green aspects). SA47 protects the points at Holemouth junction. If SA47 is routed to Severn Beach, this is the last main aspect colour light signal. Leaving aside the special GPL SA627 (which normally shows two white lights), there is a fixed distance board on approach to Severn Beach station and the stop blocks. But if SA47 is routed over to the Up Avonmouth Dock line towards Filton West, SA47 signal requires SA37 signal to be showing a proceed aspect before it will clear. SA7 signal in turn requires that SA47 is showing a green aspect...

Here, SA7 is the block section signal. The line between SA47 and Severn Beach being a One Train Working (OTW) section). For the route to the Up Avonmouth Dock line, SA37 is the next block section signal.

Also commonly used for some terminal stations, such as Liverpool Street or Manchester Piccadilly, where tracks converge onto a common "starter" signal. The starter signal will be conventional R/Y/G, but the "inner" signal will R/G and only clear if the starter is clear.

 

[headshot119]

For example, prior to the re-control of the Westerleigh to Swindon line from Bristol Panel to TVSC, signal UB103 at Chipping Sodbury tunnel was not a section signal. It was in the middle of the axle counter section. It normally showed green regardless of where trains were. The controlled signals in rear B119 (up Badminton) and B417 (goods loop) hence although three aspect colour light heads, had their middle (yellow) aspects blanked out (one had a metal plate painted black, I can’t remember what the other one had). The signal ahead (beyond) UB103 was UB99R (a two aspect colour light repeater, with yellow and green aspects), followed by UB99 (three aspect colour light).

Section signals don't exist in TCB working.

 

[D6130]

Also commonly used for some terminal stations, such as Liverpool Street or Manchester Piccadilly, where tracks converge onto a common "starter" signal. The starter signal will be conventional R/Y/G, but the "inner" signal will R/G and only clear if the starter is clear.

This also applies at some through stations where there are converging routes before the platform end starter signal. A good example is at the South end of platform 1 at Carlisle, where Through Siding 'A' joins the platform line before the platform end and drivers of Southbound trains have to obey two separate 'starting' signals - one under the canopy protecting the exit from the siding and then another one at the platform end, which applies to movements from both the platform and the siding. However, in this case, the first signal is a three aspect (R/Y/G) and the second one is a four aspect (R/Y/G/Y).

 

[john prytherch]

Where a colour light stop signal (being a running signal, not a subsidiary, and not being a searchlight or a 2 or 3 aspect LED) has more than one lens or LED aperture (is this the correct term for an LED headed signal?), the one that shows red is normally the nearest to the driver's eyes, and so normally the one at the bottom. As has been discussed, this can be different with co-acting signals on the ground, as at Lancaster.

Only very rarely do we find a signal with the normal red aspect at the top. The only example I can think of is the signal at Bushbury for leaving the Down Goods Loop (formerly the Down Through Siding) towards Penkridge. The Wolverhampton panel signal WN 22 had the red aspect at the top, and I think its WMROC successor WS 8311 continues this arrangement. I have always thought this to be because the signal (old and new) is on a fairly short post and so below a driver's horizontal straight ahead sight. Am I right in thinking this, because I cannot think of any other reason for the red being at the top.

 

[Inversnecky]

There’s a mighty strange sequence at 4:50 in this video:

Every aspect a red: what’s that about?!

 

[snowball]

There’s a mighty strange sequence at 4:50 in this video:

Specially timed to agree with the title of the Agatha Christie book "4:50 from Paddington".

 

[73128]

Liverpool Street has some ground mounted Co-acting signals approaching on the Up Electric as the main signal is obstructed by the left hand wall. The red aspect on the ground mounted signal is higher than the yellow aspect.

Presumably so that it is nearer driver's eye level.

The up fast signal (platform D) at Waterloo East also used to be not the usual ordering because it was in a constrained site below the footbridge. This one was replaced on resignalling and I think that it is now standard ordering (e.g. at bottom).

 

[Annetts key]

There’s a mighty strange sequence at 4:50 in this video:

Every aspect a red: what’s that about?!

TV documentary programmes are not exactly known for getting details of the signalling system correct. Some of what is shown has been simulated, enhanced or shown out of order, by using clips.

If you really want to know what happened, read the official reports from the public inquiries including the minutes of all the hearings.

 

[Inversnecky]

TV documentary programmes are not exactly known for getting details of the signalling system correct. Some of what is shown has been simulated, enhanced or shown out of order, by using clips.

If you really want to know what happened, read the official reports from the public inquiries including the minutes of all the hearings.

I realised, but it looked real rather than a simulation,

 

[midland1]

All three aspects looked red to me! clearly it was a simulation

 

[Annetts key]

Paddington had previously been resignalled using three and four colour light signals, most of which were standard signal heads. So there were no crazy signals with multiple red aspects.

 

[Llama]

The Ansaldo ones in the Cheadle Hulme area work differently - green at the top I think.

Ansaldo signals can show green (or red or steady single yellow) in either lamp at the same signal.

 

[Annetts key]

All three aspects looked red to me! clearly it was a simulation

Thinking about it, it’s possible the producers of the documentary saw some low quality video, possibly from a forward facing camera from a train. Some of these systems produce video where it is difficult to distinguish between red aspects and yellow aspects.

They then recreated (simulated) what they think they saw...

 

[rower40]

TV documentary programmes are not exactly known for getting details of the signalling system correct. Some of what is shown has been simulated, enhanced or shown out of order, by using clips.

If you really want to know what happened, read the official reports from the public inquiries including the minutes of all the hearings.

Also no route indicator in the box above the top aspect - which (in the case of Paddington platform starter signals) would display the line number of the next signal, before the signal can clear to yellow or green.