A Signal Question

[MarkyT]

In TCB (two aspect MAS) you also have Y/G signals preceding a stop signal. It might also be the case that a YY/G or Y/YY/G signal is provided. The key difference in MAS signalling application though is that these signals do not generally have their own operating device. They merely follow the aspect of the signal beyond by virtue of lineside circuits. In old money they were said to 'repeat' (rather than be independently controlled by the signaller) the status of the next signal - hence the 'R' suffix. They also took the number of the repeated signal plus the 'R'.

Banner's, albeit a different style of signal entirely follow a similar lineside circuit architecture (no independent control).

Since SSI days one might argue that the circuit architecture and from days of old is not so appropriate as it once was, especially as in TCB (MAS) signalling each signal regardless of type is individually identified.

Yes, for decades now on modern schemes, 'repeating' distant signals have had to possess their own unique interlocking number, rather than being allowed to be known by the number of the stop signal ahead they repeat, suffixed by a 'R' or 'RR'. Banner repeaters are usually identified by the suffix 'BR' in modern schemes.

 

[Shaw S Hunter]

I think moggie has pretty much hit the nail on the head. Effectively it was a laziness in the signal numbering protocol as semaphores were directly replaced by colour lights but it was doubtless easier for drivers to comprehend in the days when such technology was new.

 

[Railsigns]

Blimey, with all the experts on here I'm surprised no one has yet put their finger on this yet.

In AB territory the Y/G Distant as has been suggested is identified with a suffix R (or RR if an outer distant) with the triangle symbol shown on the id plate. Importantly (in AB context) it is also worked by a separate lever in the box

Most distant signals in AB territory are not identified with the suffix R, precisely because they are worked by their own separate lever in the box.

 

[W230]

My 2p worth. When I was assessed one of my managers nearly threw a wobbly over me calling a repeater a distant signal but in training I was told they were the same thing (as Railsigns alludes to). Especially as on the Brighton route (which he didn't assess me on) we had distant "R" and outer distant signals "RR".

And then, as mentioned a 'co-acter' ("CA") was just a signal showing exactly the same as the main signal but better located. Like the up at Crystal Palace for those who go down that way...

I always thought that a 'repeater' isn't really repeating what the main aspect is showing (i.e. it shows yellow when the main aspect is at red) but that's what we call them down 'ere haha!

 

[Romney Bobby]

My understanding is that all repeaters are distants, but not all distants are repeaters.

A distant is any signal that cannot display a stop aspect.

A repeater is a signal that does not have its own control means, e.g. a lever, and its aspect is determined by the next main signal in advance.

A y/g signal controlled by its own lever (or button) is a distant signal, but not a repeater ( and mostly found in rear of an AB home signal).

 

[Phil.]

As always there's numerous replies to a simple question which requires a simple answer.
The simple question was asked of a colour light signal which doesn't show a red aspect.
The answer is simple in that it's a distant signal. End of. Why all of the deep and meaningful discussions about repeaters, banners, co-actors et al which it isn't? I expect the original questioner is now somewhat confused and bemused.

Romney Bobby had it in one.

 

[GNER 91128]

BTW the signal in question is P864.

I really appreciate fellow posters taking the time to answer my question!

But knowing why the signal never shows a red aspect was what I was all I really wanted know!

 

[D Foster]

BTW the signal in question is P864.

I really appreciate fellow posters taking the time to answer my question!

But knowing why the signal never shows a red aspect was what I was all I really wanted know!

Hi-tech reason your signal never shows a red aspect - is - because - it doesn't have one - so - it can't show red. Horribly simple really.

All the discussion of distants, repeaters, co-acting and banner repeaters is kind of relevant - but a little confusing with regard to your initial question.

To try to clarify...

In normal UK "mainline" practice a Red Stop Signal - with the exception of Buffer Stop Lamps * - is never normally approached without the approaching movement first sighting a warning Yellow/Caution Indication. This Yellow is always placed at the Standard Braking Distance from the first Red signal that the movement will approach - except when it can't be placed there - when other arrangements will be introduced.

Therefore - as directly relevant to your original question as I can be - the signal never shows Red because that is not it's purpose. It is not a signal that indicates Stop" - it only indicates a warning (at a set distance) that the next signal is at Red at the time the Yellow is sighted. - When the Y/G signal is showing Green things get a bit more complicated depending on whether the signal is part of an Absolute Block, Intermediate Block or Track Circuit Block signalled area. (You want that explained?)

Therefore, whether they are called Distants or Repeaters a Y/G only signal gives indications of what is going on at the next Red capable signal beyond it.

In current practice there is some standardisation gradually occurring. Distant Signals (Identified by a white triangle above the signal number) occur in Absolute Block Areas. Repeater Signals (Identified by an R after the signal number - which is the same number as the Stop/Red capable signal beyond it) occur in Track Circuit Block Areas.

Terminology and application have developed over several decades and have varied both by location and time. So - you will simply get different responses according to date and place.

Just to generate a whole new complication some colour light signals now get a triangle over the number and the letter R after the number. I have asked people I know that currently design signalling schemes for network Rail - and - because they haven't worked on schemes that have this "double" marking they can only guess at what it means - it seems possible that it is used where a Y/G signal co-acts (in sequence with) a R/Proceed Aspect signal beyond it - i.e. it is on the same lever/control.

Having raised "co-acting". A Co-acting Signal" suffixed "CA" is an identical arm or head that is placed either directly below or directly across the track (usually in a 6ft way at low/ground level) that always shows exactly the same aspect as the main signal - except when there is a fault - in which case the combination is a "wrong Aspect" which means STOP.

A Banner Repeater is NOT a signal. It is a Banner Repeater. It repeats the indication of only the signal to which it applies and is there to provide the required sighting conditions of the signal.

From an historical point of view the whole business of outlying signals giving warning of what subsequent signals indicated started with Auxiliary Signals (in the original usage of the term c 1850s (ish) ).

* Buffer Stop Lamps are not technically signals in the conventional sense - although they do somewhat indicate "Stop". In older practice the last indication before a dead end could be a green aspect - and train crew were expected to know that they were coming to the end of the line. In more recent times Colour Light signals have shown a Yellow - in an R/Y head on the last signal on approach to the dead end. In recent practice Buffer Stop Lights are getting signal id numbers on them. This is because they are being "proved" in the circuitry that controls the aspect of the signal on the approach to them. (So that - if the Buffer Stop Lamp fails the signal on the approach will not be able to clear from Red - so the train crew will have to be talked by).

I hope this succeeds in clarifying the issue. (Apart from what occurs when the full Standard Braking Distance isn't possible )

(I guess that I shouldn't mention "Fog Repeaters" that exist on the London Underground...)(They don't exist on ""Real Railways"" :-0

 

[Railsigns]

Oh dear; so much confusion.

Wind the clock back twenty years to a time before the 'delta' plate was introduced and before it was common practice to fit ID plates to signals outside of Track Circuit Block areas. The Rule Book requires driver to treat a failed colour light signal as though it's displaying its most restrictive aspect, i.e. a 'caution' aspect in the case of a distant signal. Outside of TCB areas, there was often nothing to positively identify a signal as a distant signal; it relied on the driver's route knowledge. It was recognised that something better was needed.

Gradually, signals outside of TCB areas with fitted with ID plates. Signals were naturally plated with the number of the lever that controlled them. Since distant signals in Absolute Block etc. areas were usually worked from their own separate levers (Intermediate Block Distant signals were the main exception), simply plating them with the lever number (as well as the appropriate signal box prefix letters) wouldn't positively identify them as distant signals. For example, you might have a distant signal plated AB1, followed by stop signals plated AB2 and AB3. These might be followed by Intermediate Block Distant and Home signals, plated AB10R and AB10, respectively.

For a brief period, the signalling standards addressed this anomaly by proposing that all distant signals should be plated with an "R" suffix regardless of whether they were operated from their own lever. Taking the example above, the distant signal would be plated AB1R and be followed by stop signals AB2 and AB3. There would be no AB1. I have never seen this done in practice, but it's possible that a few distant signals worked from mechanical boxes were plated this way.

The delta plate was introduced in 1996. It is intended to be used on all colour light distant signals, irrespective of the method of working (TCB etc.) or whether a distant signal is operated from its own separate lever etc. At the same time that the delta plate was introduced, it became practice to give all distant signals in TCB areas their own individual numerical identities, without an "R" suffix. This change in numbering practice implies nothing about the way the signals are operated. I hope this goes to show that you can deduce nothing about the working of a distant signal from the way it's plated.

Intermediate Block Distant signals will commonly be seen plated with both a delta plate and an "R" suffix. The "R" is still needed to differentiate it from the I.B. Home signal which is operated from the same lever. The delta plate is fitted as well, because delta plates are intended for all colour light distant signals.

Even in TCB areas, there are distant signals with both the "R" and the delta plate. Some recent signalling alterations on the Chiltern line have retained the "R" prefixes on new distant signals, maintaining consistency within the Marylebone signalling area, but have also been fitted with delta plates, as required by standards.

Some interlocking areas have been re-controlled to new signalling centres, all signals retaining their existing numerical identities but being re-plated with a new signal box prefix code. The opportunity is taken to apply delta plates to any distant signals affected. This is yet another example of why you can have distant signals with both the "R" and a delta plate.

 

[Sunset route]

Not an answer to the original question but just to add to the mix, we have 10 of these distant signals on our district.

 

[Sig01]

.....

 

[GW43125]

A little bit of trivia I've been told by one of my colleagues-apparently you can identify a distant where there's no delta plate or r plate by having no telephone-is this true or has that changed?

 

[Tomnick]

A little bit of trivia I've been told by one of my colleagues-apparently you can identify a distant where there's no delta plate or r plate by having no telephone-is this true or has that changed?

You've been fed some nonsense there! No distant signal has a telephone (unless there just happens to be a lineside phone there). The presence or otherwise of a delta plate or 'R' suffix doesn't change that.

 

[14xxDave]

You've been fed some nonsense there! No distant signal has a telephone (unless there just happens to be a lineside phone there). The presence or otherwise of a delta plate or 'R' suffix doesn't change that.

Isn't that what he said?

D.

 

[Railsigns]

There are several stop signals that don't have telephones either.

 

[Tomnick]

Isn't that what he said?

D.

Maybe! I've read it again and I'm not sure. As Railsigns says, though, the lack of a telephone doesn't necessarily mean that it's a distant signal, so it'd be nonsense on that basis too!

 

[Joseph_Locke]

There are several stop signals that don't have telephones either.

In fact we are required to justify providing them in GSM-R fitted areas.

 

[GW43125]

Isn't that what he said?

D.

That is indeed what I said, just poorly worded.

 

[GW43125]

In fact we are required to justify providing them in GSM-R fitted areas.

I'm talking non-GSMR

 

[Railsigns]

I'm talking non-GSMR

Even without GSM-R, there are still stop signals that don't have telephones, e.g. signals close to the signal box or signals where there is no safe position to put a telephone.

 

[GW43125]

Even without GSM-R, there are still stop signals that don't have telephones, e.g. signals close to the signal box or signals where there is no safe position to put a telephone.

However those where a telephone cannot be provided due to limited clearance are usually marked, are they not?

 

[ComUtoR]

However those where a telephone cannot be provided due to limited clearance are usually marked, are they not?

Na, what they do it put a telephone there and then put a sign on it saying limited clearance don't use it. Much more efficient that way.

Signals without phones have a different symbol. The ones going in down Spa road don't have phones.

 

[Railsigns]

However those where a telephone cannot be provided due to limited clearance are usually marked, are they not?

Regardless of whether they are or not, the claim made in post #42 is still nonsense.

 

[GW43125]

Regardless of whether they are or not, the claim made in post #42 is still nonsense.

Duly noted.