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Trivia: Signals That Never Show Green

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ComUtoR

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It can read *through* a running shunt, but still needs a main aspect to read *to* at the far end of the route!

:E Couldn't resist. :E

The signal isnt cleared until the track circuit has been ocupied for a given length of time, so the signal in rear of it will never show green, only ever yellow, but it will have the capacity to show green.

Are there many approach control signals that only signal one route ? I thought they were used to signal a diverging route. Off my head I can't think of any that show just the one route. The signals before can show for the main aspect or for the approach controlled route.

I'd be interested to know why you would get a single route being approach controlled. Purely for a step down in speed?

Cheers in advance.
 

BS56

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I guess the line used to continue into some sidings and they have been removed but are still "present" in the signaling.
That photo was taken at Aberdare station . The line went to Hirwaun to Tower colliery some four miles further down the line ! I did not know the line is now closed. The signal is a fixed red . The ground frame in the distance controlled the shunt signal to the left of the main aspect also you can see the back of a ground signal for coming off the branch.
 

Ianno87

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There used to be a signal approaching Bolton on the old (now removed) Down Slow at Burnden Jn...it could only display up to YY even though you could access all through platforms from it. I presume from that signal all trains were starting from a stand or low speed so there was no advantage in recieving a Green.


:E Couldn't resist. :E



Are there many approach control signals that only signal one route ? I thought they were used to signal a diverging route. Off my head I can't think of any that show just the one route. The signals before can show for the main aspect or for the approach controlled route.

I'd be interested to know why you would get a single route being approach controlled. Purely for a step down in speed?

Cheers in advance.

I think there's one on one of the Temple Mills lines between Bow and Stratford in the Down direction - all available routes are diverging so the 'straight' route has no onward signalled route.
 

Tomnick

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:E Couldn't resist. :E

Are there many approach control signals that only signal one route ? I thought they were used to signal a diverging route. Off my head I can't think of any that show just the one route. The signals before can show for the main aspect or for the approach controlled route.

I'd be interested to know why you would get a single route being approach controlled. Purely for a step down in speed?

Cheers in advance.
Thought you might be on the wind-up ;)

I can think of one example (albeit not quite fitting your criteria) - there’s two routes from the signal, but both are approach released. It’s at the end of a relatively short bi-di section on the approach to a diverging junction. Whichever way you’re going (40mph vs 35mph, free greens both ways if you’re coming in the right direction) you have to come through a 15mph crossover first. Presumably that’s why it’s approach released, the risk of misleading yourself into thinking that you’re on the right line rather than bang road. The signal in rear (a distant signal) is only capable of showing a single yellow, but it’s a single-aperture LED head so you wouldn’t know the difference just by looking at it.
 

ComUtoR

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How do you protect against a wrong route is your signaled the same for both routes ? Just drop the speed down and confirm when it pulls off ?

I think we (and others) have had this discussion before but I find it oddly fascinating. Our SIMBID has a fixed distant so works the same way (both being bi-di). I've only been through it once (many moons ago) so I couldn't tell you if the exit back to the mainline is/can be approach controlled (I suspect it is)

If a junction was ALWAYS approach controlled, why would the one in the rear be capable of showing green ? I see the logic in a fixed distant. Could the one in the rear be switched to approach control (like the reduced overlap thingies) and then stepped up to green ?

Cheers guys.
 

razor89

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ML110 approaching Birkdale is 3 aspect but will never show green as ML108 is approach controlled, due to the proximity of crescent road AHB between Birkdale and Hillside.
 

urpert

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The principle of only showing a yellow reading up to a terminal platform was used at Victoria Eastern during Resignalling in about 1980. To ensure uniformity (particularly for drivers) the equivalent signals on the approach to Victoria Central (resignalled soon after) were altered on the same weekend as were those at Waterloo.
That’s interesting. Is this not standard practice at all terminal stations then?
 

Snow1964

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There is a 3 aspect at Lymington Junction (Lymington Line approaching Brockenhurst) that can only show Green if routed through platform 1 or 2 AND the level crossing is cleared.

Existed since Junction was closed and parallel line opened (about 1978)
 

Sad Sprinter

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In the words of Fred Dinage:

“Signal VC536 turns to double yellow. Being so close to the terminus, the signal cannot display green.”

I don’t know how many times I’ve watched Video 125s “Connex Express” DEV over the years but the answer probably is too many!
 

Snow1964

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Of course this doesn't count but at Beaulieu Road, the down signal (towards Weymouth) is a signal that only shows green and yellow, but never red.

Brockenhurst - Lymington Junction was resignalled a decade after these 2 aspect colour lights in New Forest. Very rare distant after Sway as it was a 3 aspect distant in advance of the 4 aspect at Lymington Junction (so had 2 yellows and a green, but no red). Might not be there anymore as 3 aspect signals replaced the Sway-Christchurch 2 aspect few years ago. Can’t ever remember seeing another distant with double yellows
 

Belperpete

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That’s interesting. Is this not standard practice at all terminal stations then?
At Waterloo and Victoria, where the long platforms could accommodate two trains, the early colour-light signalling used to show green if the platform was completely empty, and yellow if the inner part of the platform was occupied. As Tim M said, this practice was abolished in the early 80s.
 

Belperpete

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I can think of one example (albeit not quite fitting your criteria) - there’s two routes from the signal, but both are approach released. It’s at the end of a relatively short bi-di section on the approach to a diverging junction. Whichever way you’re going (40mph vs 35mph, free greens both ways if you’re coming in the right direction) you have to come through a 15mph crossover first. Presumably that’s why it’s approach released, the risk of misleading yourself into thinking that you’re on the right line rather than bang road. The signal in rear (a distant signal) is only capable of showing a single yellow, but it’s a single-aperture LED head so you wouldn’t know the difference just by looking at it.
If there are two routes from a signal, then it should only be necessary to approach control the slower of the two routes. If there is only one route from a signal, then it shouldn't need approach control. The exception to this is where a route has a junction indicator (e.g. at the end of bidi working where the only route is back over the crossover, that route will have a junction indicator so the driver doesn't think he is going straight on bang-road) - in such cases, that route should be approach-controlled so that the signal doesn't clear before the junction indicator is visible. However, in such cases, as you say, the signal in rear is inherently not capable of showing green.

On one scheme I was working on, the scheme designer had shown a working green aspect and an AWS electro magnet on the signal in rear, but we got them removed from the plan.
 

Belperpete

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How do you protect against a wrong route is your signaled the same for both routes ?
Signalling principles say that if both routes from a signal have roughly equal speeds (within 10mph difference), then it is not necessary to tell the driver in advance which way he is routed. The only exception is where it may be unsafe for a train to take one route, or there are exceptional operational issues - the example I recall in the principle is where only one route is electrified. Applying approach control just to tell the driver which way he is going is obviously undesirable, hence the introduction of splitting distants and preliminary route indicators in cases where it is considered important enough (as opposed to just inconvenient if the train takes the wrong route).
 

David Dunning

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Brockenhurst - Lymington Junction was resignalled a decade after these 2 aspect colour lights in New Forest. Very rare distant after Sway as it was a 3 aspect distant in advance of the 4 aspect at Lymington Junction (so had 2 yellows and a green, but no red). Might not be there anymore as 3 aspect signals replaced the Sway-Christchurch 2 aspect few years ago. Can’t ever remember seeing another distant with double yellows

I remember that one too. I used to live at Ashurst and did many a walk thru the forest by the tracks. I think there was another on the approach to Brockenhurst travelling west at the end of the long straight bit. Also I seem to remember one outside of Cosham too (on the eastbound line) Were they designed to give advanced warning of the state of the level crossing ahead? A double yellow would indicate barriers down and clear into platform but not to leave it. Remember when the Forest was re-signalled for electrification in the late 60s Service 91 was fast and didn't stop there (Same with Cross Country too in the 70s)
 

Tomnick

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How do you protect against a wrong route is your signaled the same for both routes ? Just drop the speed down and confirm when it pulls off ?
We’ve got a few like that. One’s 70mph both ways, even faster on the approach - you’ve got no chance if you’ve been wrong routed. Another (80mph approach, 45 vs 30 at the junction) is quite poorly sighted - you don’t see the junction indicator in particular until quite late on. In both cases, it’d all be on the signalman if a wrong route was taken. There’s a few others that are much lower speed on the approach, and I guess the expectation there is that you should be able to stop in time - I know one of them was done a while back, not sure what the outcome was.

If there are two routes from a signal, then it should only be necessary to approach control the slower of the two routes. If there is only one route from a signal, then it shouldn't need approach control. The exception to this is where a route has a junction indicator (e.g. at the end of bidi working where the only route is back over the crossover, that route will have a junction indicator so the driver doesn't think he is going straight on bang-road) - in such cases, that route should be approach-controlled so that the signal doesn't clear before the junction indicator is visible. However, in such cases, as you say, the signal in rear is inherently not capable of showing green.

On one scheme I was working on, the scheme designer had shown a working green aspect and an AWS electro magnet on the signal in rear, but we got them removed from the plan.
This one has a theatre indicator - you can see the signal, but not the indicator, when the signal clears. I guess that the principle’s the same though - a reminder that you’re on the wrong road and about to cross back over.

(approaching Radford Junction on the Down, if you know it?)
 

Ianno87

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The signal (CA163) protecting the scissors crossover at Cambridge on the Through Line in the Down direction must rarely show green. It requires a non-stopping train to be signalled right through Cambridge running wrong-line...which doesn't happen much.
 
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Dave W

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The platform 2 starter at Stourbridge Junction (used to be SJ87 but that may have changed now) will only show yellow for everything except running on to Round Oak, which is only a maximum of two or three times a day out of many dozens of movements.

The signal protecting the junction to Birmingham is approach released.

I’m not familiar with the preceding signal, so if it was 4 aspect then that’d be in a similar situation - I don’t know if there’s any 4 aspect round there though.
 
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Brockenhurst - Lymington Junction was resignalled a decade after these 2 aspect colour lights in New Forest. Very rare distant after Sway as it was a 3 aspect distant in advance of the 4 aspect at Lymington Junction (so had 2 yellows and a green, but no red). Might not be there anymore as 3 aspect signals replaced the Sway-Christchurch 2 aspect few years ago. Can’t ever remember seeing another distant with double yellows

Distant?
a colour light distant can not show a red aspect.
a distant has two states, when on is means one or all of the signals in advnace of it within station limits are at danger or the signal itself has not been cleared, or if off then all the stop signals in advance of it in station limits are also off.

A 3 aspect colour light signal therefore can not be a distant. No matter how you think of it.
 
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:E Couldn't resist. :E



Are there many approach control signals that only signal one route ? I thought they were used to signal a diverging route. Off my head I can't think of any that show just the one route. The signals before can show for the main aspect or for the approach controlled route.

I'd be interested to know why you would get a single route being approach controlled. Purely for a step down in speed?

Cheers in advance.

Approach release is provided when the route in advance changes speed by 10mph or more. that can apply to one or all routes off the signal.
The speed limits are not always the same after the signal, why would you think they are?

If there are two routes from a signal, then it should only be necessary to approach control the slower of the two routes. If there is only one route from a signal, then it shouldn't need approach control. The exception to this is where a route has a junction indicator (e.g. at the end of bidi working where the only route is back over the crossover, that route will have a junction indicator so the driver doesn't think he is going straight on bang-road) - in such cases, that route should be approach-controlled so that the signal doesn't clear before the junction indicator is visible. However, in such cases, as you say, the signal in rear is inherently not capable of showing green.

On one scheme I was working on, the scheme designer had shown a working green aspect and an AWS electro magnet on the signal in rear, but we got them removed from the plan.

As above. Why do you assume one one or more of the routes has a lower line speed?
 

111-111-1

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Distant?
a colour light distant can not show a red aspect.
a distant has two states, when on is means one or all of the signals in advnace of it within station limits are at danger or the signal itself has not been cleared, or if off then all the stop signals in advance of it in station limits are also off.

A 3 aspect colour light signal therefore can not be a distant. No matter how you think of it.

In some 4 aspect areas being approached from a 2 commonly or sometimes 3 aspect area or from an AB fringe box it is possible.

1st signal SB xx RR available aspect combinations G YY
2nd signal SB xx R G YY Y
3rd signal SB xx G YY Y R
 

Y Ddraig Coch

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Forgive the thread resurrection, but this morning I found myself staring at LJ68 as I passed it, and noticed that it has two lamp positions on the signal head, not just the one. Whether a green or yellow bulb was ever fitted to it is another matter!

Is there a reason why Network rail don't just remove it? It must need maintaining that costs time and money and last time it was needed (ie train running wrong road towards it) must have been mid 90s at the latest. Maybe even earlier and even then if I recall it was only on a couple of times on a Sunday to give Conwy a service.
 

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edwin_m

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The definition of a "distant" in the signalling glossary GK/GN0802 is:
A Signal (not itself a Stop Signal) capable of displaying a Cautionary Aspect that informs the driver of the state of the Signals or Level Crossing ahead.
The suffix R or RR indicates a repeater signal, which automatically shows the relevant aspect depending on that of the stop signal beyond with the same number. The glossary simply considers "repeater" to be a non-preferred alternative term for a distant, but a worked distant isn't a repeater.
 

sw1ller

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Is there a reason why Network rail don't just remove it? It must need maintaining that costs time and money and last time it was needed (ie train running wrong road towards it) must have been mid 90s at the latest. Maybe even earlier and even then if I recall it was only on a couple of times on a Sunday to give Conwy a service.

by that logic (and it is sound logic, but we’re talking about the railway here) then why have they not decommissioned PR19 at penmaenmawr on the up sidings or what I THINK is CR109 at Chester just before windmill lane tunnel on the down sidings. Both signals are buried in bushes and can’t have been used in 20+ years.
 

edwin_m

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Sometimes the line is still nominally available for use because it hasn't been through network change, and NR would have to make it useable if anyone wanted to use it.

In other cases bits of track may be removed from the network but the associated signaling not altered, probably because of the difficulty of modifying safety-vital signaling but perhaps also to avoid re-briefing and risk of confusing drivers if any of the signals themselves are modified. Some less invasive measure would be needed to ensure trains couldn't be signaled onto the non-existent track! This isn't just a NR thing - there was a loop at Sheet Stores Junction that went out of use sometime in the 80s but the signal was still lit many years later even after various components of the exit points had disappeared.
 

Snow1964

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Distant?
a colour light distant can not show a red aspect.
a distant has two states, when on is means one or all of the signals in advnace of it within station limits are at danger or the signal itself has not been cleared, or if off then all the stop signals in advance of it in station limits are also off.

A 3 aspect colour light signal therefore can not be a distant. No matter how you think of it.

This particular signal protected a 4 aspect home signal (at Lymington junction) and was about a mile before it (so was a repeater or distant signal). The previous signal with a red was near New Milton (in the 2 aspect area, where the home signals were about every 3-4 miles. So distant would show single yellow if home was red (crossovers in use), double yellow if cleared to platforms, and green if level crossing (beyond platform) was ready. It was a sole 4 aspect signal in the area, but Brockenhurst still had a few sidings and a motorail terminal when resignalled so shunting and crossing moves still happened

It was presumably due to different signalling policies, at different dates, the 2 aspects had been installed around 1966 as part of the Bournemouth electrification, but Lymington junction retained semaphones until about 1978 (a lower frequency service was in force before 1974 with some trains every 2 hours).
 
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In some 4 aspect areas being approached from a 2 commonly or sometimes 3 aspect area or from an AB fringe box it is possible.

1st signal SB xx RR available aspect combinations G YY
2nd signal SB xx R G YY Y
3rd signal SB xx G YY Y R

RR or R are repeater signals


I didn't say they would be.



A colour light signal that had 2Y, 1Y, or G would meet that definition.



a fixed distant only has one state.

No.
If it has a green off aspect then it is not a distant.
The rule regarding distants are above.

There are rules that denote what a distant signal is.
A fixed distant is just that, a distant signal that can not be cleared and so is usually provided as a board with a reflective background. Any moves past it are always cautionary.

I think the problem is terminology.
People think of repeaters as distant signals, where are the name distant signal means something in its own right.

The definition of a "distant" in the signalling glossary GK/GN0802 is:

The suffix R or RR indicates a repeater signal, which automatically shows the relevant aspect depending on that of the stop signal beyond with the same number. The glossary simply considers "repeater" to be a non-preferred alternative term for a distant, but a worked distant isn't a repeater.

Exactly that.

This particular signal protected a 4 aspect home signal (at Lymington junction) and was about a mile before it (so was a repeater or distant signal). The previous signal with a red was near New Milton (in the 2 aspect area, where the home signals were about every 3-4 miles. So distant would show single yellow if home was red (crossovers in use), double yellow if cleared to platforms, and green if level crossing (beyond platform) was ready. It was a sole 4 aspect signal in the area, but Brockenhurst still had a few sidings and a motorail terminal when resignalled so shunting and crossing moves still happened

It was presumably due to different signalling policies, at different dates, the 2 aspects had been installed around 1966 as part of the Bournemouth electrification, but Lymington junction retained semaphones until about 1978 (a lower frequency service was in force before 1974 with some trains every 2 hours).

A repeater is a repeater and a distant is a distant.


Though all this I find it most interesting that you guys seem to associate a signal to be a signal in its own right...
Consider a junction with approach release.
One route can present a green off aspect depending on signal in advance of it along that route, while the other route, lets say the diverging route is signalled in such a way so that the signal can only ever present a yellow cautionary aspect...
Does that signal fit in with the criteria? Because to me it does as when that diverging route is set is can not display a green off aspect.
 

ComUtoR

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GERM8000-traindriver Iss 7.pdf

Distant signal
A distant signal is a signal which cannot show a stop aspect or indication.
Some colour light distant signals are identified by a white triangle or the letters ‘R’ or ‘RR’ on the signal identification plate

Nothing says that a distant cant have a green, only that it doesn't have a 'stop aspect'
 
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