A Signalling Sighting Conundrum

[beast66606]

There was a 'bracket' type signal mounted on a brick retaining wall coming off the Lambourn branch at Newbury, if you can find a photo of it - purely in terms of a 'prototype for everything'..

 

GW Signalling iirc

[beast66606]

How about a 2 aspect colour light on the floor instead ?

 

3-aspect would be required, otherwise a green onto a red would ensue

[Tim V]

It always worries me that modellers regard the aspect of signals like a traffic light. An On indication would not be a surprise, as the distant would have informed the driver that the next signal could be on.

 

I remember driving in Greece, where the traffic lights had what were effectively distants, the drivers just sped up if they saw the repeater change!

[cb900f]

3-aspect would be required, otherwise a green onto a red would ensue

 

Sorry Beast,

With respect I have to disagree with you there, a 2 aspect stop colour light signal would display red/green as per a semaphore stop signal. A green onto a red would still ensue even if it was a semaphore.

If a driver was stopped and then the signal was cleared (green) the driver would proceed cautiously being prepared to find the next stop signal displaying a red aspect.

All a bit academic really.

 

Regards Pete

[Edwin_m]

I'm with Beast on this one. In the unusual situation where an isolated colour replaces a semaphore stop signal, it will show a yellow if the next stop signal remains at red. Unless there is full braking distance between the two stop signals, and a clear overlap beyond the second one, then the train will have been cautioned at the distant so will approach at reduced speed. With a red/green colour light there is considered to be a risk of the driver momentarily forgetting this is a semaphore area and disregarding the next semaphore signal. It also has the advantage that a green will tell the driver that all remaining stop signals are clear and he can accelerate away.

 

This is described in my Kitchenside and Williams from the 1970s so has been the case for several decades at least.

[Steve Hewitt]

Banner repeaters are seldom modelled so why not put one in because it would look interesting?

 

Geoff Endacott

 

These working banner repeaters have been on Blackburn's "Oxenholme" layout for many years:

Courtesy Railway Modeller

 

Steve.

[The Stationmaster]

Sorry Beast,

With respect I have to disagree with you there, a 2 aspect stop colour light signal would display red/green as per a semaphore stop signal. A green onto a red would still ensue even if it was a semaphore.

If a driver was stopped and then the signal was cleared (green) the driver would proceed cautiously being prepared to find the next stop signal displaying a red aspect.

All a bit academic really.

 

Regards Pete

 

 

 

How peculiar, and downright dangerous. If a colour light signal shows a green aspect a Driver is absolutely right to understand that the next signal in advance will be displaying a 'proceed' aspect - although it might of course be a caution aspect - and that in normal circumstances he will not be expected to bring his train to a stand at it.

The requirement has always been that a red/green 2 aspect colour light can only read to to a signal which is not capable of showing a 'stop' (i.e. red) aspect (n.b. different conditions apply on low speed lines such as, say, the Newcastle Metro). The only exception to this which I know of was when red/green was used to read into terminal platforms (and i won't bother to explain al the permutations therein over the years as they aren't relevant here).

And, in order to avoid any further confusion could you possibly link us to the source of your (incorrect) information?

 

 

[The Stationmaster]

GW Signalling iirc

 

 

 

But of course - quite a nice signal too But I'm reasonably sure you'll find the Midland did something similar where it had to, somewhere in the sort of 'Kentish Town-ish' area rings a bell somewhere in the murkier depths of my memory.

 

 

[beast66606]

As StationMaster says, some low speed systems have some strange signalling.

 

Merseyrail has red/greens leading onto red/greens, it also has yellow/green repeaters for the next signal and also has yellow/green over red/green which can show double green (thats a stop and a repeater, they don't combine into a 3-aspect on the underground section, the outside part does where appropriate though) - I blame flyingsignalman myself, there "his" signals

[The Stationmaster]

While I was reading down through the thread, I was thinking that an Outer Home would be required, to enable you to drop down to the junction, then I found Dave's comments, which reinforced my own views.

 

There was a 'bracket' type signal mounted on a brick retaining wall coming off the Lambourn branch at Newbury, if you can find a photo of it - purely in terms of a 'prototype for everything'..

 

If you have the main junction home signal where Dave sketched it in on the photo, and given 'modellers licence/layout compression', perhaps you could have an outer home mounted on a bracket coming out of the retaining wall between the tunnel and bridge, possibly with a small/bespoke arm with a centre pivot?

 

Operation of the layout could thus demonstrate junction acceptance - ie. the train stopping at the Outer Home when a conflicting route was set ahead of it at the junction.

 

Drivers would be assumed to have a full and comprehensive route knowledge and would know that if the distant signal for these homes was 'on', then he should not expect any of them to be clear until he saw them, hence a cautious approach would be called for (slow linespeed notwithstanding).

 

 

 

I'm starting from here for several reasons so this not meant to be a criticism of the Cap'n's post per se. Over the years I've given a lot of thought to the application of selective compression to signalling on layouts as the prototype distances can get distinctly silly if strictly applied. I think that to give soem impression of realism the 'model' diytance between an Outer Home and the next stop signal in advance has to be at least 'a good long train length' to ensure that any train coming towards the Outer Home is seen to be well clear of any activity such as a junction immediately in advance of the next signal. As train lengths vary I think it is reasonable to represent 'a good train length' as a loco plus around half a dozen coaches. the reason for choosing that figure is that many layouts can't or don't run trains that long so the Outer Home is going to be forced away - possibly out of sight. Make the distance too short and it will look silly. Others will obviously have their views on how the distance might be compressed.

The next step then is to properly understand acceptance under such conditions. The Regulations have for a very long time been quite specific and we have had a 440 yard Clearing Point - no other trains in or about to foul it and points correctly set. Ignoring any special acceptance authority a Signalman cannot accept a train if he doesn't have a Clearing Pont - so a train won't be creeping towards the junction or anything else, it will be standing at the signalbox/fiddle yard in rear waiting 'Line Clear'. Or alternatively it will have arrived and be at a stand at the signal protecting the Clearing Point before any conflicting movement etc can take place. Or if there is an Outer Home Signal for acceptance purposes it will have been accepted but will stop at that signal until conditions in advance of the next signal are such that it can proceed.

So on a model railway the train either is not there at all, or is at a stand at the Home Signal, or is at a stand at the Acceptance Outer Home Signal - but it is NOT slowly creeping towards the signal protecting the junction.

Those ar the bare basics and ignore the relaxation of the Clearing Point with a colour light distant from the 1980s on or such niceties and Warning Signals etc and we'll totally overlook certain things the GNR happened to do in the West Riding.

 

[The Stationmaster]

As StationMaster says, some low speed systems have some strange signalling.

 

Merseyrail has red/greens leading onto red/greens, it also has yellow/green repeaters for the next signal and also has yellow/green over red/green which can show double green (thats a stop and a repeater, they don't combine into a 3-aspect on the underground section, the outside part does where appropriate though) - I blame flyingsignalman myself, there "his" signals

 

At which juncture I'll jump right off the thread (with due apologies to Adam) and include this one for its sheer entertainment value - double red over (miniature) green. However because the signal reproduces contemporary (a long time ago contemporary) semaphore signals one of the reds is actually a distant signal at caution - some aspects (sorry) of Sydney suburban signalling are fascinating.

 

 

 

 

[Edwin_m]

Looks a bit like the old Watford DC lines signalling on steroids.

[ikcdab]

Two questions here need answering.

firstly, there is no need to have a semaphore stop signal right up against the junction if the sighting would be bad. There many examples like this where the home signal was quite a way in rear of the junction - and in this case i think the home would be on the approach side of the bridge. Track circuiting would prevent conflicting moves.

secondly - if you have a colour light outer home it would certainly be a two-aspect signal displaying just red/yellow. This would have an approach lock: if the inner home is clear then the outer home colour light would clear to yellow as soon as the switch is turned: however if the home is held on and the outer home is cleared,then it will normally be held at red until the train approaches. As it occupies a short track circuit in rear of the signal then it would clear to yellow automatically at that point.

[TheSignalEngineer]

Two questions here need answering.

firstly, there is no need to have a semaphore stop signal right up against the junction if the sighting would be bad. There many examples like this where the home signal was quite a way in rear of the junction - and in this case i think the home would be on the approach side of the bridge. Track circuiting would prevent conflicting moves.

secondly - if you have a colour light outer home it would certainly be a two-aspect signal displaying just red/yellow. This would have an approach lock: if the inner home is clear then the outer home colour light would clear to yellow as soon as the switch is turned: however if the home is held on and the outer home is cleared,then it will normally be held at red until the train approaches. As it occupies a short track circuit in rear of the signal then it would clear to yellow automatically at that point.

 

A colour light outer home would normally be a 3 aspect signal as it would need to be showing green to clear the distant for a run through.

[beast66606]

Two questions here need answering.

 

So answer them I will.

 

firstly, there is no need to have a semaphore stop signal right up against the junction if the sighting would be bad. There many examples like this where the home signal was quite a way in rear of the junction - and in this case i think the home would be on the approach side of the bridge. Track circuiting would prevent conflicting moves.

 

Not really, most semaphore signalling was done "at the limit", if only one home was provided it would be at the clearing point for the junction, i.e so a loco standing at it would be clear of the main line. Track circuiting detects the present of trains, electric locks prevent conflicting moves.

 

secondly - if you have a colour light outer home it would certainly be a two-aspect signal displaying just red/yellow. This would have an approach lock: if the inner home is clear then the outer home colour light would clear to yellow as soon as the switch is turned: however if the home is held on and the outer home is cleared,then it will normally be held at red until the train approaches. As it occupies a short track circuit in rear of the signal then it would clear to yellow automatically at that point.

 

Highly unlikely to be a red/yellow, this were very rare beasts indeed, in fact I can't think of one off the top of my head but I did draw a signalling plan a few years back for a member on here which could use one. Approach locking could be provided, but thats nothing to do with the physical signal, its because the local requirements are to ensure the train is under control before the signal is cleared, to any proceed aspect.

What switch are you talking about, it's a lever frame in the box. The signal would clear to yellow if any of the remaining semaphores (along the route) were at danger (red), but it would clear to green if they were all off.

 

The track circuit is referred to as a berth track btw.

 

I think you are getting confused somewhere along the line (so to speak)

[TheSignalEngineer]

Sorry Beast,

With respect I have to disagree with you there, a 2 aspect stop colour light signal would display red/green as per a semaphore stop signal. A green onto a red would still ensue even if it was a semaphore.

If a driver was stopped and then the signal was cleared (green) the driver would proceed cautiously being prepared to find the next stop signal displaying a red aspect.

All a bit academic really.

 

Regards Pete

 

In a semaphore area the only colour light signal to be a two aspect red/green would be a starting signal into the next Block Section or an Intermediate Block Section. Clearing a colour light signal to green in such an area implies that the line is clear up to the clearing point of the first Home signal (440yards semaphore/ 200yards colour light) at the next block post or the overlap of the Intermediate Block Home Signal. Trains are not allowed to run from a green aspect on a colour light signal to a red aspect or a semaphore signal in the 'on' position.

 

Red/green signals were used on BR for routes into empty platforms at terminal stations at one time but this was rapidly changed after the Moorgate Tube Disaster.

 

Charles

[Adam]

No worries Mike (Stationmaster), this is all very interesting and, whatever else, means that what gets modelled will be an informed decision. The stop signal is under way anyway...

 

Adam

[ikcdab]

So answer them I will.

 

 

 

Not really, most semaphore signalling was done "at the limit", if only one home was provided it would be at the clearing point for the junction, i.e so a loco standing at it would be clear of the main line. Track circuiting detects the present of trains, electric locks prevent conflicting moves.

 

 

 

Highly unlikely to be a red/yellow, this were very rare beasts indeed, in fact I can't think of one off the top of my head but I did draw a signalling plan a few years back for a member on here which could use one. Approach locking could be provided, but thats nothing to do with the physical signal, its because the local requirements are to ensure the train is under control before the signal is cleared, to any proceed aspect.

What switch are you talking about, it's a lever frame in the box. The signal would clear to yellow if any of the remaining semaphores (along the route) were at danger (red), but it would clear to green if they were all off.

 

The track circuit is referred to as a berth track btw.

 

I think you are getting confused somewhere along the line (so to speak)

 

Hopefully not!!

 

I am thinking of modern usage which if course would be different to older setups. I am thinking of a situation of a mechanical box with a semaphore home protecting a low-speed junction like here. the outer home is a colour light which is worked from a block shelf switch rather than a lever - though of course i realise that in some cases it would be attached to a cut down mechanical lever. In this case, the outer home would be a red/yellow light. three scenarios:

a. the home is at danger and the outer home is cleared. As the train approaches the outer home will clear to yellow as the train occupies the berth track circuit: the signal acts as a distant and cautions drivers as they approach the home which is on.

b. the home is cleared and the outer home also cleared. In this case the outer clears to yellow immediately.

c. a train is standing outside the home. As the outer home is more than 440yds in rear, a second train can approach the outer home - but in this case the outer is held on and shows a red.

 

Again, this is more-modern usage at the approach to a low speed junction in some situations. Not saying it is common, but it does occur.

[cb900f]

Hi Charles, Beast and Mike.

 

Clearly your knowledge of block and signaller's regulation is better than mine but it does state in the rule book module S2 2.1for the driver that :-

 

If you are stopped or nearly stopped at either of the following types of signal and that signal changes to a proceed aspect, you must understand that the next signal maybe at danger:

 

. a colour light signal that cannot display a yellow aspect

 

. a semaphore signal

 

Regards Pete

[beast66606]

Hopefully not!!

 

I am thinking of modern usage which if course would be different to older setups. I am thinking of a situation of a mechanical box with a semaphore home protecting a low-speed junction like here. the outer home is a colour light which is worked from a block shelf switch rather than a lever - though of course i realise that in some cases it would be attached to a cut down mechanical lever. In this case, the outer home would be a red/yellow light. three scenarios:

a. the home is at danger and the outer home is cleared. As the train approaches the outer home will clear to yellow as the train occupies the berth track circuit: the signal acts as a distant and cautions drivers as they approach the home which is on.

b. the home is cleared and the outer home also cleared. In this case the outer clears to yellow immediately.

c. a train is standing outside the home. As the outer home is more than 440yds in rear, a second train can approach the outer home - but in this case the outer is held on and shows a red.

 

Again, this is more-modern usage at the approach to a low speed junction in some situations. Not saying it is common, but it does occur.

 

I still think you are getting confused

 

Switches are unusual when performing the functions of a lever with a lever frame still present and still controlling some of the signals in the area - do you have a specific example in mind ?

 

Addressing your points

a - true but it doesn't act as a true distant unless it's braking distance from the inner, it's acting as a "they aren't all off yet"

b - not necessarily true - if the inner was the only semaphore the outer would go to green, if it wasn't then it would still be approach controlled unless it was braking distance from the inner (if it shows yellow it means the next signal is likely to be red, so it has to be braking distance from the inner to get a straight yellow (ie not track circuit released)

c - not true unless the rear of the train is at least 440yds (or 200 for a colour light) from the outer, block regs still apply.

 

hth

[beast66606]

Hi Charles, Beast and Mike.

 

Clearly your knowledge of block and signaller's regulation is better than mine but it does state in the rule book module S2 2.1for the driver that :-

 

If you are stopped or nearly stopped at either of the following types of signal and that signal changes to a proceed aspect, you must understand that the next signal maybe at danger:

 

. a clour light signal that cannot display a yellow aspect

 

. a semaphore signal

 

Regards Pete

 

Interesting but I have a feeling that something subtle has been missed in the wording somewhere, the semaphore I know to be true, as a local signalman - to me - pulls of his home 1, home 2, home 3 as soon as he is offered a train, but leaves the starter and the distant at caution until it has been accepted by the box in advance, the caution at the distant means drivers can't assume all the stop signals are off, so they should expect one to be at danger he argues - I don't agree with his method of working, but I'm not his manager

[cb900f]

Interesting but I have a feeling that something subtle has been missed in the wording somewhere, the semaphore I know to be true, as a local signalman - to me - pulls of his home 1, home 2, home 3 as soon as he is offered a train, but leaves the starter and the distant at caution until it has been accepted by the box in advance, the caution at the distant means drivers can't assume all the stop signals are off, so they should expect one to be at danger he argues - I don't agree with his method of working, but I'm not his manager

 

I would agree with you and would add that it is a recipe for a SPAD.

However I would also add that if this method is carried out on a regular basis, the bush telegraph will spread the word to the relevant T/Crews working over the section of line concerning this malpractice.

Unfortunately this would still not exonerate a driver in the event of a SPAD.

 

Regards Pete

[Swindon 123]

I have read through all the arguments on this topic with interest. From a drivers point of view I would like to make the following observations. It would appear that any proposed signal by the junction would be very close to said junction, and that a SPAD by a train would foul the overlap for that signal ,ie. foul the junction. This would fall into the old "Warning Arrangement" scenario. Section clear, station or junction blocked. In all the instances I have come across like this as a driver in both semaphore and colour light MAS signalling, I would expect to be checked right down or even stopped at the signal before the one at the junction before being signalled forward, under the warning arrangement either by a subsidiary signal showing a "W", the previous signal being cleared slowly by the signalman in semaphore areas, or a 3 aspect colour light clearing to a yellow, in both semaphore and MAS situations. At Abbey Foregate (Shrewsbury) when routed round the loop towards the Hereford road, the set up being very similar in layout to the one in this topic, I even had the old "Green flag out the box" from the signalman. Whether any additional signals for the above method of working are put on the layout or considered to be off scene would be up to the builders to decide.

 

Paul J.

[ikcdab]

I still think you are getting confused

 

Switches are unusual when performing the functions of a lever with a lever frame still present and still controlling some of the signals in the area - do you have a specific example in mind ?

 

 

yes..Bishops Lydeard works exactly like this on the up into the station. The colour lights are worked by switches on the block shelf and the down outer home (signal BL102) works as i have described.

[beast66606]

yes..Bishops Lydeard works exactly like this on the up into the station. The colour lights are worked by switches on the block shelf and the down outer home (signal BL102) works as i have described.

 

I'm afraid preserved railways often have their own way of doing things, it's also a single line (I think) which generally means that all distants are fixed, I assume the outer home is being considered as having a fixed distant because of the token exchange, comparing a single track passing place on a preserved railway to a double track junction (granted, mythical) from the 1960s is chalk and cheese though.