Separate post co-acting signals

[DavidBird]

I'm well aware of the principle of co-acting signals, where there are two arms on one post, one at eye-level and another at a height to be seen (for example) over a preceding bridge.

 

Was there ever an example of a co-acting signal with the two arms on separate posts, possibly because of sighting around a curve?

 

Thanks

[bécasse]

Don't ask me to quote examples, but once upon a time there certainly were a handful of examples of co-acting signals on separate posts around the network. The sighting problems had to be pretty extreme before separate posts were resorted to, but inevitably it happened in congested areas.

[Miss Prism]

Google 'banner repeater signals'.

[micknich2003]

I'm almost certain, there is a ref, or drawing in one of the early text books, I will try and find it later.

[martin_wynne]

Was there ever an example of a co-acting signal with the two arms on separate posts, possibly because of sighting around a curve?

 

Hi David,

 

To have two posts they would have to be next to one another, or possibly on opposite sides of the track. Otherwise you could not apply the rules for not passing it. A running signal has a single location relative to the track.

 

Instead, for advanced sighting a banner repeater signal is used. There is a picture of one here: http://www.roscalen.com/signals/Abergele/

 

regards,

 

Martin.

[beast66606]

Yes, Tairmebion on the North Wales Coast had such an example.

[DavidBird]

Yes, a Banner Repeater would be the "normal" situation, but as I've found out from this group if there is an alternative way, somebody, somewhere will have done it.  I'd worked out that if there were two posts for the same signal they would need to be at the same point along the track.

 

Any pictures of Tairmebion?

[martin_wynne]

Yes, a Banner Repeater would be the "normal" situation, but as I've found out from this group if there is an alternative way, somebody, somewhere will have done it.  I'd worked out that if there were two posts for the same signal they would need to be at the same point along the track.

 

When asking a question on RMweb and expecting other members to take the trouble to reply, it is helpful to indicate what you already know.

 

Martin.

[The Stationmaster]

When asking a question on RMweb and expecting other members to take the trouble to reply, it is helpful to indicate what you already know.

 

Martin.

I thought he did Martin - the question was about co-acting signals, i.e. a signal with two arms serving the same function where each acts in unison with the other.  I'm sorry to get pedantic but the question - unless I have gravely misread it - was not about banner repeaters, or indeed any other sort of repeater, but about co-acting arms and they are not the same thing at all.

[martin_wynne]

I thought he did Martin - the question was about co-acting signals, i.e. a signal with two arms serving the same function where each acts in unison with the other.  I'm sorry to get pedantic but the question - unless I have gravely misread it - was not about banner repeaters, or indeed any other sort of repeater, but about co-acting arms and they are not the same thing at all.

 

Hi Mike,

 

He asked about multiple signals in relation to sighting problems. I don't see how a helpful reply to that would not mention banner repeaters, unless he specifically states that he is not asking about them. In making replies here most folks try to be as helpful as possible to a fellow modeller, rather than pedantically responding to the exact wording of a question. This is a hobby forum, not an examination room.

 

Martin.

[The Stationmaster]

Hi Mike,

 

He asked about multiple signals in relation to sighting problems. I don't see how a helpful reply to that would not mention banner repeaters, unless he specifically states that he is not asking about them. In making replies here most folks try to be as helpful as possible to a fellow modeller, rather than pedantically responding to the exact wording of a question. This is a hobby forum, not an examination room.

 

Martin.

He didn't Martin - he  very specifically asked 'Was there ever an example of a co-acting signal with the two arms on separate posts, possibly because of sighting around a curve?'  So he wasn't talking about banner repeaters (or in strict terms about any sort of repeater) but about co-acting arms, i.e, two arms that work in unison.

 

A repeater (when working correctly) does exactly what it says on the tin - it repeats the indication given by the signal it applies to but it cannot indicate that signal/signal arm is 'off' until it actually is 'off'.  If the arm it is repeating is at 'wrong' (in repeating terms) the banner should not show 'off' but should remain at 'on'.  However if a co-acting signal arm is at 'wrong' both arms will be 'wrong' (assuming they are correctly adjusted of course) and giving an imperfect indication to the Driver of an approaching train.  Hence we are talking about two totally different things and it doesn't matter whether or not the OP does or doesn't know anything about banner repeaters, he was asking about co-acting arms.

 

In this case I thought the question was pretty precise, it was about co-acting arms.  No need for an examination, test paper or anything else - just a straightforward question.  Sorry to get pedantic Martin but as you well know in relation to matters concerning trackwork there can be specific terminology involved and the very phrasing of the question made it clear the OP knew exactly what he was asking.  To me it very clearly indicated what he wanted to know and it would seem that several respondents to his question took a similar view.

[martin_wynne]

the very phrasing of the question made it clear the OP knew exactly what he was asking.  To me it very clearly indicated what he wanted to know and it would seem that several respondents to his question took a similar view.

 

Mike,

 

In that case he should have asked it on a specific signalling web site. RMweb is about modelling.

 

On a modelling web site, the assumption is that the question relates to modelling unless the context is clearly otherwise, or the questioner says otherwise. I reasonably assumed that he had a sighting problem for a model signal and was asking what to do about it. A banner repeater is one obvious solution, and one other respondent also steered him towards banner repeaters. So I went to the trouble to find a link illustrating one. No thanks for doing so, just a "I already knew all that". He could easily have said so in the first place.

 

Martin.

[beast66606]

Yes, a Banner Repeater would be the "normal" situation, but as I've found out from this group if there is an alternative way, somebody, somewhere will have done it.  I'd worked out that if there were two posts for the same signal they would need to be at the same point along the track.

 

Any pictures of Tairmebion?

 

Not here in Germany I'm afraid ! - imagine a 15' tall signal to the left of the running line and a 25' signal to the right of both lines.

[Edwin_m]

I believe the colour lights at the north end of East Midlands Parkway had and may still have co-actors on the opposite side of the double track.  There was a topic on this on the Signal Box forum which is currently closed. 

[LNERGE]

Stevenage North 11 and 17 signals..

 

[DavidBird]

 

 

Apologies for the somewhat ambiguous wording of my original question - of course I should have mentioned I already knew that a banner repeater is the normal solution, and even as an amateur, I can think of several real examples off the top of my head.  The point about both posts needing to be at exactly the same location only occurred to me later and I suspect this may be the reason why the "double post co-acting" was almost never used.

 

Many thanks to all who for your replies, and especially to Martin for the link to pictures of Abergele, I'd not seen those before. 

 

The pictures prompt another question, (apologies if this should be in the "prototype" section) What is the reason for the double-post arrangement of the down splitting home, rather than the more usual bracket?

[martin_wynne]

Stevenage North 11 and 17 signals..

 

Wouldn't co-acting signals be on the same lever?

 

Martin.

[beast66606]

Instead, for advanced sighting a banner repeater signal is used. There is a picture of one here: http://www.roscalen.com/signals/Abergele/

 

Rather ironically the banner was provided in the early 1980s as the LMS signal which was around 50' high with co-acting arms and visible for miles when approaching from Rhyl, was replaced with a standard 15' signal which wasn't visible until the train was very close to it.

[The Stationmaster]

Wouldn't co-acting signals be on the same lever?

 

Martin.

Yes - as they clearly are in the example posted by LNERGE, presumably arranged in that way because of the overbridge at the end of the platform.  What would be interesting to know is what the arms looked like as the diagram implies they are miniature yellow arms - and that makes it an extremely interesting use of them (was there an Instruction in the Appendix I wonder because otherwise passing them at danger would technically have contravened the Rules?).

 

 

The pictures prompt another question, (apologies if this should be in the "prototype" section) What is the reason for the double-post arrangement of the down splitting home, rather than the more usual bracket?

This arrangement was relatively common in later years on the 'northern ' Regions - and there was at one time an extremely tall co-acting splitting signal on the North London Line which combined both co-acting arms and the use of a pair of posts (very tall lattice in that case I think) as a splitting signal.  In some cases it was done because ground conditions couldn't take the weight of/support a bracket signal but in later years I suspect it was mainly done that way as it was cheaper and simpler as a crane wasn't needed to erect such signals.  When it was done with very tall signals (as the LNWR did) it was probably, again, simpler and easier to erect than a tall bracket structure.

[Rivercider]

Not on separate posts but, at Totton there was a tall LSWR signal with the co-acting lower arm on a bracket due to sighting difficulties,

there is a picture in 'British Railways Southern Region in Colour' by Kevin Robertson 

 

cheers

[martin_wynne]

Yes - as they clearly are in the example posted by LNERGE, presumably arranged in that way because of the overbridge at the end of the platform.  What would be interesting to know is what the arms looked like as the diagram implies they are miniature yellow arms - and that makes it an extremely interesting use of them (was there an Instruction in the Appendix I wonder because otherwise passing them at danger would technically have contravened the Rules?).

 

Thanks Mike. If they are at different locations should they be called repeaters rather than co-acting? Might there be some detection to prevent them clearing until the main arm has done so?

 

Martin.

[Grovenor]

 

What is the reason for the double-post arrangement of the down splitting home, rather than the more usual bracket?

I was always taught that separate posts was the preferred arrangement as it is simpler and cheaper. However, in reality siting would usually enforce use of brackets or gantries as most of the ground space was occupied by tracks. The Abergele one in the pic has been made possible by removing much of the track.

Regards

Keith

[LNERGE]

What would be interesting to know is what the arms looked like as the diagram implies they are miniature yellow arms - and that makes it an extremely interesting use of them (was there an Instruction in the Appendix I wonder because otherwise passing them at danger would technically have contravened the Rules?).[/i]

They were simply yellow miniature arms.

 

Edit to add.. There are red miniature arms on the down slow too but they were not mentioned by me as they are on the same post. The sexual upendix makes no mention of any of them.

[LNERGE]

The best i can do searching the net apart from the really good close ups i have that are not mine to post<g>

 

https://www.flickr.com/photos/70023venus2009/8213613255/sizes/l

[The Stationmaster]

Thanks Mike. If they are at different locations should they be called repeaters rather than co-acting? Might there be some detection to prevent them clearing until the main arm has done so?

 

Martin.

Technically they are co-acting because they are on the same levers (i.e. 11 & 17) but you can get into some interesting variations of terminology, for example the GWR called its co-acting arms 'Duplicate Arms' which was at least meaningful in the sense that it duplicated the arm mounted above (a long way above in some cases).  Equally the GWR seems to have reserved the term 'repeater signal' for the situation where they were provided at stop signals in rear of the signal at the actual divergence, in those cases they were worked by separate levers and they were signals at which a train had to come to a stand if the signal was at danger ( so a repeater at which a train had to halt!) - fortunately the Company set about getting rid of them in the early part of the 20th century.

 

The Stevenage arrangement is interesting in a number of ways as they have used miniature yellow arms (which mean the same as a yellow disc)for 11 & 17 in an unusual (for such signals) situation however some strange things happened signalling wise on the Southern Division of the LNER and I presume these arms were used as there wasn't really an alternative without inventing one from scratch.  What I am not entirely sure about is whether or not they could be passed at danger although I'm inclined to presume that if they could not there wouldn't be so much sense in using a yellow arm - maybe they were, hopefully, covered in the relevant Sectional Appendix and somebody who has one can enlighten us?

 

A further interest is that there are two methods of mounting co-acting arms right next to each other and that in both cases the co-acters use the old method of signalling a divergence with the arms one above the other on the same post - co-acting colour light signals simply aren't in the same ball game for that sort of interest and variety.