MadMac
Member
ARS on Edinburgh doesn't set route over Princes Street Gardens for a train stopping at Haymarket, until that train has left Haymarket station.
I predate ARS by quite some time
ARS on Edinburgh doesn't set route over Princes Street Gardens for a train stopping at Haymarket, until that train has left Haymarket station.
It can read *through* a running shunt, but still needs a main aspect to read *to* at the far end of the route!
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.
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.I guess the line used to continue into some sidings and they have been removed but are still "present" in the signaling.
Couldn't resist.
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-upCouldn't resist.
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.
That’s interesting. Is this not standard practice at all terminal stations then?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.
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.
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.That’s interesting. Is this not standard practice at all terminal stations then?
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.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.
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).How do you protect against a wrong route is your signaled the same for both routes ?
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
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.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 ?
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.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.
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
Couldn't resist.
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.
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.
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.
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!
The speed limits are not always the same after the signal, why would you think they are?
Distant?
a colour light distant can not show a red aspect.
a distant has two states,
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.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.
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.
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
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.
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.
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).
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