Are there any "proper" two aspect signals on the network?

[Egg Centric]

Are there any "proper" two aspect signals on the national rail network? I'm aware there are two aspect signals, obviously. Even some one aspect ones! But the "spirit" of this question is about tube style red/green signals where the previous aspect was green, with no repeaters. IE the signal sequence a driver sees is G-R. Shunting/position lights also don't count.

 

[Lucy1501]

The Merseyrail Loop line is almost exclusively signalled under two aspect R/G signals. The sighting distance for most signals is the braking distance, and tripcocks are able to bring a train to a stop in the overlap.

Some repeaters are provided for those with restricted sighting - either on their own or on same signal post as the stop signal, only showing a light when the signal is off (similar to a semaphore distant under semaphore stop arrangement).

To quote Network Rail’s “Additional Instructions in respect of Mersey, link and loop sections”

On the Mersey Section and Loop line colour light signals are normally of the 2 aspect type (red/green). When the sighting of the signal is restricted, a colour light repeating signal is provided, which displays a green aspect when the signal ahead is in the clear position and a yellow aspect when the signal ahead is at Danger.

 

[edwin_m]

This would be very unusual under multiple-aspect signalling because the normal rule is that a train will never see a red unless it's seen a yellow at braking distance before it (except when starting away from a dead end). The Mersey Tunnels are a special case because of the low speed, sighting not impeded by weather conditions, and use by EMUs with good braking. There are probably places where a green is followed by a red but there is a fixed distant board to take the place of the yellow, but I can't think of any offhand.

It is of course possible with semaphore signals in Absolute Block areas. Most boxes have more than one stop signal for each direction, but the distant can only be cleared if all the stop signals are also cleared. The signaller can clear a stop signal to let the train proceed to the next one, but only when they are sure the train is under control. In this situation the last stop signal (the section signal) could be a R/G colour light, but if any of the others are colour lights then they must be three-aspect.

 

[godfreycomplex]

I’m pretty sure that the Mersey Tunnels are indeed the only example of these but I am open to correction if there are more.

However the standard very much is to provide a repeater in all situations and as a result new installations of this type of system haven’t been approved for quite a while. My understanding is that it had grandparent rights dating from before the Sandhills resignalling and has just remained that way ever since. All new installations are mandated to have repeaters of some kind, and have been for many years.

There are quite a few green-fixed distant-red type places (Henley, Sudbury and Blackpool South to name but three) as this is allowed under signalling standards as it counts as a warning

 

[Boilinthebag]

Colour light replacements in semaphore areas would see a driver get a green followed by a red light possibly if the distant was at caution? I don't know if there are two consecutive colour light replacements anywhere under absolute block?

 

[driverd]

Colour light replacements in semaphore areas would see a driver get a green followed by a red light possibly if the distant was at caution? I don't know if there are two consecutive colour light replacements anywhere under absolute block?

I've never known that - anywhere I've seen a semaphore replaced by a colour light, you'll get the appropriate aspect. Eg: if the section was a semaphore and on, the home a colour light and the distant a semaphore, you would see semaphore distant on, 3 aspect CL showing yellow, semaphore section on.

I'm not saying the set up you describe isn't installed somewhere, it's just not something I've ever seen or known (and I sign a fair chunk of AB across a wide area).

 

[Magdalia]

The Fen Line still has traditional signal boxes, but with all of the semaphore signals replaced by colour lights.

For example, the platform end signals at Downham Market may be red/green only, I will try to remember to check next time I'm there.

 

[edwin_m]

I've never known that - anywhere I've seen a semaphore replaced by a colour light, you'll get the appropriate aspect. Eg: if the section was a semaphore and on, the home a colour light and the distant a semaphore, you would see semaphore distant on, 3 aspect CL showing yellow, semaphore section on.

I'm not saying the set up you describe isn't installed somewhere, it's just not something I've ever seen or known (and I sign a fair chunk of AB across a wide area).

The Fen Line still has traditional signal boxes, but with all of the semaphore signals replaced by colour lights.

For example, the platform end signals at Downham Market may be red/green only, I will try to remember to check next time I'm there.

As I posted above, it's OK for the section signal to be a red-green colour light but if a colour light replaces any of the stop signals before it, then it must be a three-aspect. I recall Kitchenside and Williams (British Railway Signalling) explained the risk that a driver would see a bright green colour light and fail to remember or see that there was a dim red semaphore a little way beyond it. Digression, but nobody seems that bothered that in pure semaphore areas the driver must rely on route knowledge to know which one the section signal is (as this being clear indicates the train can accelerate into the section).

Sometimes the three-aspect colour light can be at full braking distance from the next stop signal (which is itself probably also a colour light due to its distance from the box). In that case the distant can show green even if the three-aspect is at yellow, giving the signaller a bit more flexibility to keep two trains in the vicinity of the box.

Most modern LED signal types can show different colours through the same "lens", so it's not possible to tell at a glance what aspects a particular signal is intended to show.

 

[Lucy1501]

My understanding is that it had grandparent rights dating from before the Sandhills resignalling and has just remained that way ever since. All new installations are mandated to have repeaters of some kind, and have been for many years.

James Street PSB was established in 1977 alongside the opening of the loop and link lines, consisting of two panels (for the loop and link).

The link line was built with conventional 3 aspect signalling throughout, however the loop line was an extension of the Mersey Railway’s existing network which was predominantly 2 aspect. The 2 aspects reached out as far as Birkenhead Central and Birkenhead Park signal boxes at the time of opening.

The Merseyrail IECC works were mostly just a recontrol of James Street PSB. I would probably be of the opinion that it’s not just grandfathered in, but it’s a different style of signalling system altogether - a hybrid metro signalling rather than proper heavy rail signalling.

 

[edwin_m]

James Street PSB was established in 1977 alongside the opening of the loop and link lines, consisting of two panels (for the loop and link).

The link line was built with conventional 3 aspect signalling throughout, however the loop line was an extension of the Mersey Railway’s existing network which was predominantly 2 aspect. The 2 aspects reached out as far as Birkenhead Central and Birkenhead Park signal boxes at the time of opening.

The Merseyrail IECC works were mostly just a recontrol of James Street PSB. I would probably be of the opinion that it’s not just grandfathered in, but it’s a different style of signalling system altogether - a hybrid metro signalling rather than proper heavy rail signalling.

Also worth noting that Merseyrail has tripcocks, and I assume the signalling is designed with long enough overlaps to stop a train being tripped from maximum permitted speed. Tyne and Wear Metro is similar, though with a different form of trainstop, most stations just havinbg red/green platform starters and a warning sign on approach.

 

[30907]

Digression, but nobody seems that bothered that in pure semaphore areas the driver must rely on route knowledge to know which one the section signal is (as this being clear indicates the train can accelerate into the section).

My memory is hazy, but I thought that if the section signal was at danger the previous stop signal would only be cleared when the approaching train was seen to have slowed? Perhaps one of our resident signallers could confirm/correct? So not entirely a matter of route knowledge.

 

[RailwayRookie]

The Fen Line still has traditional signal boxes, but with all of the semaphore signals replaced by colour lights.

For example, the platform end signals at Downham Market may be red/green only, I will try to remember to check next time I'm there.

Both platform signals at Downham are Red/Green but are both preceeded by three aspect signals, (and an associated repeater before each of those)

DM11 sits at the Up end of the Down platform for moves onto the signal line the from the 'wrong' direction. This is also a Red/Green but can only be approached from a Semaphore shunt signal before hand and subsequently is fully visible from said shunt signal.

As far as I know, ever other R/G signal on the Fen line has a three aspect or repeater before it.

 

[brad465]

If this example counts, Grove Park Platform 1 has a 2-aspect signal at the London end with no distant signal before the next [4-aspect] signal on the Up Fast, almost certainly because these two signals are in such close proximity, on a 20mph section, that a driver would be able to see both signal aspects at the same time in almost all conditions.

 

[Railsigns]

If this example counts, Grove Park Platform 1 has a 2-aspect signal at the London end with no distant signal before the next [4-aspect] signal on the Up Fast, almost certainly because these two signals are in such close proximity, on a 20mph section, that a driver would be able to see both signal aspects at the same time in almost all conditions.

The 2-aspect signal for Platform 1 (TL320) won't clear unless a route is set from the 4-aspect signal beyond (TL318).

 

[MarkyT]

Both platform signals at Downham are Red/Green but are both preceeded by three aspect signals before hand, (and an associated repeater before each of those)

DM11 sits at the Up end of the Down platform for moves onto the signal line the from the 'wrong' direction. This is also a Red/Green but can only be approached from a Semaphore shunt signal before hand and subsequently is fully visible from said shunt signal.

As far as I know, ever other R/G signal on the Fen line has a three aspect or repeater before it.

When selected semaphores were replaced ad hoc with colour lights controlled from a lever frame, yellow and double yellow aspects were provided to create a standard aspect sequence, sometimes with odd timing controls to counter a lack of braking distance between subsequent intermediate former semaphores. The section signal could be R/G only because the next signal is the distant for the next signalbox.

 

[Sheridan]

My memory is hazy, but I thought that if the section signal was at danger the previous stop signal would only be cleared when the approaching train was seen to have slowed? Perhaps one of our resident signallers could confirm/correct? So not entirely a matter of route knowledge.

Well yes, but if the driver then accelerates up towards linespeed because they think it’s the section signal but in fact that’s still ahead, then there’s a far higher possibility of a SPAD. Let’s say a box has a distant signal and four semaphore stop signals (three home and one section). If the distant is on, and each semaphore clears on approach, it’s only down to route knowledge that the driver knows which one is the section signal. I think that’s the point that the previous poster was making.

 

[Magdalia]

Both platform signals at Downham are Red/Green but are both preceeded by three aspect signals before hand, (and an associated repeater before each of those)

Thanks for this, saves me having to look next time I'm there!

The up platform starter (DM3) has a further unusual feature with the red and green lamps placed horizontally not vertically on the signal post.

 

[MarkyT]

Thanks for this, saves me having to look next time I'm there!

The up platform starter (DM3) has a further unusual feature with the red and green lamps placed horizontally not vertically on the signal post.

For good sighting under the canopy I expect. Birmingham New Street had a number of signals with R/Y/G arranged horizontally. They replaced original 1960s 'searchlights' with only 1 aperture through which all 3 colours were displayed. A modern searchlight form LED signal would be the ideal solution today.

 

[edwin_m]

My memory is hazy, but I thought that if the section signal was at danger the previous stop signal would only be cleared when the approaching train was seen to have slowed? Perhaps one of our resident signallers could confirm/correct? So not entirely a matter of route knowledge.

Well yes, but if the driver then accelerates up towards linespeed because they think it’s the section signal but in fact that’s still ahead, then there’s a far higher possibility of a SPAD. Let’s say a box has a distant signal and four semaphore stop signals (three home and one section). If the distant is on, and each semaphore clears on approach, it’s only down to route knowledge that the driver knows which one is the section signal. I think that’s the point that the previous poster was making.

Yes, that was the point I was trying to make. Distant signals are now fitted with a plate showing a triangle symbol, and I'm rather surprised there isn't some other symbol for a section signal.

For good sighting under the canopy I expect. Birmingham New Street had a number of signals with R/Y/G arranged horizontally. They replaced original 1960s 'searchlights' with only 1 aperture through which all 3 colours were displayed. A modern searchlight form LED signal would be the ideal solution today.

I don't think any of the horizontal signals still exist at New Street - they have been replaced by multi-colour LEDs as you suggest.

The mid-platform signals on the two southernmost platforms at Newcastle Central also had horizontal three-aspect signals on creation of these platforms in the early 90s, but not sure what they have now.