SIGNALLING WITH COLOUR LIGHTS

[TheSignalEngineer]

At least nowadays we don't call or prove Level Crossings down in the Overlap.

 

Simon

Was it ever done Simon?  (Possibly in E10,000 circuits but not otherwise I suspect although no doubt Signal Engineer will be along to help us out - 

 

From memory if the protecting signal is more than 50 metres from the crossing or more than 25 metres if on a station platform, then there was no requirement to prove the crossing closed to road traffic in order for a train to approach the signal. In certain circumstances the provision of a delayed aspect at the signal in the rear was considered. If the protecting signal was less than the minimum distance from the crossing then controls were sometimes added to require the crossing sequence to have started before the signal in the rear could be cleared. At crossings adjacent to stations it was quite common for the barriers to remain up until the train was in the station.

[The Pilotman]

Was it ever done Simon?  (Possibly in E10,000 circuits but not otherwise I suspect although no doubt Signal Engineer will be along to help us out - 

 

 

Can you remember what it was like at Causeway and Appleford as they were much older design circuitry than the B&H crossings?  (Although I'm fairly sure scratching back a long way in memory that the same applied at Worle and the crossing wasn't an obstruction in the overlap - i.e. effectively roughly the same as an Absolute Block Clearing Point).

please)

Mike, I worked both crossing boxes several times and, although it's nearly twenty years ago, I'm fairly sure that Appleford crossing wasn't in the overlap of either the up or down line protecting signals (the signal for the line coming out of the refuse/stone sidings was close enough but didn't have an overlap as such). On the down at Causeway, again, the crossings were not in the overlap but Causeway crossing certainly was on the up line and you could route a train up to the protecting signal (R5) with both crossings open to road traffic. The signal in rear was an automatic so you must have been able to.

[The Stationmaster]

Mike, I worked both crossing boxes several times and, although it's nearly twenty years ago, I'm fairly sure that Appleford crossing wasn't in the overlap of either the up or down line protecting signals (the signal for the line coming out of the refuse/stone sidings was close enough but didn't have an overlap as such). On the down at Causeway, again, the crossings were not in the overlap but Causeway crossing certainly was on the up line and you could route a train up to the protecting signal (R5) with both crossings open to road traffic. The signal in rear was an automatic so you must have been able to.

 

Thanks - I should have remembered that the signal in rear of R5 was an auto; put it down to age please

[71000]

That's very interesting; I was always under the impression that a crossing that was open to road traffic did not count as an obstruction in an overlap. I'm not sure what the set up is now but in the Reading Panel era when Colthrop crossing box was in operation (maybe it still is?) it was possible to allow a stopping train into Thatcham station in the down direction with the crossing beyond open to road traffic even though the protecting signal at the end of the platform was a matter of yards from the very busy road beyond. I know it was possible because I've done it myself.

O

[71000]

Sounds like somebody had got their 'old fashioned' an confused.  Under Absolute Block Signalling a train can be accepted under full Line Clear up to a Home Signal (the outermost Home Signal in order to remove doubt) which might only be a matter of feet from a level crossing which it protects and on which the gates are open to road traffic.  (In other words the rough equivalent of having a level crossing in an overlap with the signal in rear of the protecting signal able to clear to a proceed aspect)

T

[The Stationmaster]

Then assuming a crossing is just a few feet from the protecting Home signal and a large steam loco is hauling the train, the driver is fully entitled to hit the cars on the crossing if his cab is 40ft or so from the front of the locomotive.

 

You seem to have forgotten that due to sighting and braking problems by the driver of a steam loco, you had to have an overlap in such a situation.

 

In addition when two Home signals exist before a "Starting" signal, the first is called the "Outer Home" and the second one the "Inner Home" to clearly distinguish the two and avoid confusion, under at least two other rules !!! .      

 

No such situation existed under "Absolute Block" rules in steam days and for some years after, as an overlap was required of 220yds in such a situation because steam hauled and even diesel hauled unfitted freight had a nasty habit of not stopping quite where they were supposed too.  

 

A good example of such requirements was demanded by the Inspecting Officer of the West Somerset Railways resignalling of Bishops Lydeard station only around 12 years ago. Despite the ruling maximum speed on the WSR of 25mph, (Officially). Approaching from Minehead a train is on a down gradient. The WSR in their wisdom placed the Junction Home signal only around 50yds from the pointwork giving access to either of the 2 platforms. The Inspecting Officer still demanded that an Outer Home be placed at least 220yds prior to the Junction Home signal and therefore requiring a working Distant as well. In addition track circuitry would be necessary to prove that a route into a clear platform, was possible and the route set BEFORE an approaching train passed the Outer Home. These extra requirements were also in view of the fact that the then "Wales & West" Operator, was pursuing a plan to extend some Bristol-Taunton local services to Bishops Lydeard station, to terminate in a Bay platform at the Taunton end of the station, and at least 220yds beyond the Junction Home signal !!!

 

Wales & West gave up their idea as the WSR could not afford the costs of signalling and pointwork alterations (to Exeter panel box) at the point where the WSR connected to the mainline to deal with regular timetabled through trains. The current connection is as far as I'm aware simply "clipped & padlocked" and only useable on rare ocassions for through "specials".        

 

What on earth are you on about?  Drivers are, and always have been required to stop their train at signals at danger - and not in advance of it.  As the old saying among many Signalmen goes - "that side of it is yours (i.e. the Driver's) and this side of it is mine" - 'it' being a  stop signal.  There is no such thing as an overlap in semaphore signalling and as you might have read above it is perfectly permissible to have a  level crossing within the overlap with multiple aspect signalling.

 

The rearmost stop signal at a signalbox is the Home Signal - that is now relatively standard although it has always been GWR/WR practice to call it the Home Signal, on the LMR it would be 'Home 1' and other Railways/Regions had their own practice.

 

And I repeat - there was/is no such things as an 'overlap' in Absolute Block Signalling and there never has been and probably even in today's daft world there never will be.  And incidentally a proper Clearing Point would not exist 220 yds between an Home Signal and Inner Home Signal unless the distant signal is a colour light and It would I think be silly for the WSR not to follow usual standards in signalling.  In fact logically it might be far more sensible to have the Home Signal well in excess of 440yards in rear of the splitting Home and, ideally nowadays, provide an advanced Starting Signal at least 440yyds from the Home which would allow an engine to run round while a train is accepted from Crowcombe (or a train to be accepted while a run-round is taking place) as the South Devon have done at Buckfastleigh. 

[TheSignalEngineer]

As my first Divisional Engineer told me back in the 1960s  "Drivers are paid to stop the train before it passes a red signal. If they could do it 100% we wouldn't need to provide overlaps."

[Mike Storey]

At Wye (between Ashford and Canterbury West) I very vaguely recall being allowed to accept and clear the Up Home to Up stoppers into the Up platform with the level crossing gates open, when I relieved there (as a Duty Station Manager at Ashford, covering for a signalman gone sick - we had 7 boxes we were expected to be able to operate in an emergency) in 1985-ish. Would I be right?

 

The Up Starter was at the Up end of the platform about 20 yards from the gates. The gates were manually operated and interlocked by lever frame using an  annett key. All AB, all semaphores, but track circuited. 

[Junctionmad]

is it not the case that if a train was accepted with the clearing point fouled , then the train would be checked at the proceeding signal, I presume that is the basis that the train was accepted in the first place.

[Junctionmad]

I'm confused , this is the IRSE definition 

 

"An OVERLAP of at least 440 yards for semaphore signals or 200 yards (180 metres) where both the HOME and DISTANT are COLOUR LIGHT SIGNALs. Distances vary dependant on line speed. "

 

​but then I'm often confused 

[beast66606]

I'm confused , this is the IRSE definition 

 

"An OVERLAP of at least 440 yards for semaphore signals or 200 yards (180 metres) where both the HOME and DISTANT are COLOUR LIGHT SIGNALs. Distances vary dependant on line speed. "

 

​but then I'm often confused 

 

RSSB says - and note that only 1 definition refers to Block Signalling, and not unsurprisingly it's as SM says.

 

Clearance Point

 

The point in Block Signalling beyond the Home Signal up to which the line

must be clear before a signalled Running Movement can approach the home Signal

 

 

Overlap (OL)

 

The distance beyond a Stop Signal that must be clear, and where necessary Locked,

before the Stop Signal preceding the Stop Signal in question can display a Proceed Aspect

[The Stationmaster]

is it not the case that if a train was accepted with the clearing point fouled , then the train would be checked at the proceeding signal, I presume that is the basis that the train was accepted in the first place.

 

Level crossings do not count as an obstruction within the Clearing Point (unless somebody has changed it recently).

 

Thus the situation at Wye described by Mike Storey would be absolutely correct - provided he didn't clear the Home Signal until the train was almost at a stand at it.  Over the years it no doubt occurred at numerous places around the railway network especially where level crossings were busy with road traffic.

 

I'm confused , this is the IRSE definition 

 

"An OVERLAP of at least 440 yards for semaphore signals or 200 yards (180 metres) where both the HOME and DISTANT are COLOUR LIGHT SIGNALs. Distances vary dependant on line speed. "

 

​but then I'm often confused 

Regrettably I have seen the same error made in an IRSE document I was given to check - albeit one for an 'interest' group within the IRSE and not circulated outside that group (but possibly available on the 'net).

 

is it not the case that if a train was accepted with the clearing point fouled , then the train would be checked at the proceeding signal, I presume that is the basis that the train was accepted in the first place.

If a train is accepted with the Clearing Point obstructed it would only be where what was once known as the 'Warning Arrangement' (rather different in the modern regulations) was authorised to be applied in respect of that particular Class of train.  The fact that the train had been accepted under the Warning could be conveyed to the Driver in a variety of ways - ideally by a subsidiary Warning Signal, or by a handsignal from the Signalman, or if the train had been brought to a stand at the section Signal by that signal being lowered cleared on the basis that the Driver would understand that it indicated that the line was only clear to the next Stop Signal in advance  (i.e. the outermost Home Signal at the next signalbox); in practical terms the latter method was generally to be avoided if possible as it was the least positive way of doing the job.

[Junctionmad]

I know we are a little off topic here , but its an aspect that has sometimes confused me 

 

beast6666 has provided a definition of " overlap " are  we saying this is erroneous  

 

I understand the warning arrangement applies to the clearing point , but I would dispute the Beasts ! definition of clearing point. surely using Rule 39(a) a train can approach a home signal , checked and then cleared even if the clearing point is fouled ? Or is the fouling pioint only of reference to the first Home signal , as in an outer home 

 

the thing I find a little confusing , is if a train cannot  normally be accepted into the block section because the clearing point is fouled , how can rule 39(a) ever apply to outer homes ? .  or it is that once the clearance point is unobstructed the train can be accepted , but if say the inner home is "on", then rule 39(a) applies to the all proceeding home signals , even though the train has been correctly accepted and not under a warning arrangement, if you see what I mean . 

 

where that leaves our overlap I dont know, but there are numerous references to the 440yard  issue that , either Stationmaster is right or Beast is right ?

[Grovenor]

The "clearing point" is to give line clear on the block and it relates only to the first home signal. With a clearing point obstructed you could accept from the previous box under the warning arrangement if authorised and the bobby at the previous box had to give the warning.(Regulation 5 in the 1960 block regs, bell code 3-5-5).

 

Rule 39A is a different animal and applies to bringing the train forward from the first home to an inner home or starter. There is no clearing point in this case. It is in the rule book, not the block regulations as it is effectively station working, not block working.

 

The issue is that, if a driver passed the distant at on then found the home off he may assume that he had been accepted through and pass the home with insifficient braking distance to stop at the next signal. Hence the requirement to keep the home on until the train is nearly at a stand.

Regards

[beast66606]

where that leaves our overlap I dont know, but there are numerous references to the 440yard  issue that , either Stationmaster is right or Beast is right ?

 

Patently and SM and I agree with each other so please don't make out we are disagreeing.

 

A perfect example of why I rarely provide assistance on signalling anymore - too much time spent correcting the mistakes others introduce

[Mike Storey]

Level crossings do not count as an obstruction within the Clearing Point (unless somebody has changed it recently).

 

Thus the situation at Wye described by Mike Storey would be absolutely correct - provided he didn't clear the Home Signal until the train was almost at a stand at it.  Over the years it no doubt occurred at numerous places around the railway network especially where level crossings were busy with road traffic.

 

Regrettably I have seen the same error made in an IRSE document I was given to check - albeit one for an 'interest' group within the IRSE and not circulated outside that group (but possibly available on the 'net).

 

If a train is accepted with the Clearing Point obstructed it would only be where what was once known as the 'Warning Arrangement' (rather different in the modern regulations) was authorised to be applied in respect of that particular Class of train.  The fact that the train had been accepted under the Warning could be conveyed to the Driver in a variety of ways - ideally by a subsidiary Warning Signal, or by a handsignal from the Signalman, or if the train had been brought to a stand at the section Signal by that signal being lowered cleared on the basis that the Driver would understand that it indicated that the line was only clear to the next Stop Signal in advance  (i.e. the outermost Home Signal at the next signalbox); in practical terms the latter method was generally to be avoided if possible as it was the least positive way of doing the job.

 

Quite so. It was the practice on the SR, in AB sections, where the Home had no calling on or W indication and was operated directly by rodding, to raise the signal "slowly", having checked a train at it, as an indication (or reminder if 39A was already in operation) that the station limits were not clear, usually for an assistance move or a reversal (when the next signal section was blocked, such as for engineering works), and, if there was no phone on the Home signal, the signal person would hold a red flag out to the driver to stop and receive instructions, if no flagman had yet been sent to the Home or Outer Home. Bit of a problem at motorised Homes or Outer Homes, to which many had been converted by time in ops, so the train would have to be stopped completely and the driver would have to climb down and receive instructions on the signal phone.

[Junctionmad]

Patently and SM and I agree with each other so please don't make out we are disagreeing.

 

A perfect example of why I rarely provide assistance on signalling anymore - too much time spent correcting the mistakes others introduce

I merely pointed out that you provided a definition for something that SM said didn't exist. , if you feel you shouldn't contribute , why post at all

[Junctionmad]

The "clearing point" is to give line clear on the block and it relates only to the first home signal. With a clearing point obstructed you could accept from the previous box under the warning arrangement if authorised and the bobby at the previous box had to give the warning.(Regulation 5 in the 1960 block regs, bell code 3-5-5).

 

Rule 39A is a different animal and applies to bringing the train forward from the first home to an inner home or starter. There is no clearing point in this case. It is in the rule book, not the block regulations as it is effectively station working, not block working.

 

The issue is that, if a driver passed the distant at on then found the home off he may assume that he had been accepted through and pass the home with insifficient braking distance to stop at the next signal. Hence the requirement to keep the home on until the train is nearly at a stand.

Regards

Thank you for that , concise and clear

[beast66606]

I merely pointed out that you provided a definition for something that SM said didn't exist. , if you feel you shouldn't contribute , why post at all

 

Did you miss SMs bit about in ABSOLUTE BLOCK ? he never said such things don't exist  -  for your information the definitions I posted are quotes from the RSSB rule book - so what you dismissed is what has been, and is still being, taught to signallers. It's not me that needs to think about my contributions, my posts are factually correct.

[The Stationmaster]

I think the confusion arises because of the sloppy way in which some people refer to or use the word overlap (and I don't include Beast in that as he was merely quoting something from the fount head of all amateurism - the RSSB).  And yes, I have a very poor opinion of them, and yes I do have a current Master Rule Book, and yes I receive the amendments to it, and yes I also write write Rules and Regulations and and have done over many years for BR (part of the job), and both Railtrack and Network Rail (paid in the past as an external consultant by them to do work they either didn't have the expertise to do such as for example translating equipment technical instructions into railway operational instructions, or which they simply didn't have enough staff to do the job themselves).

 

So let's get right back to basics.  In all the systems of signalling devolving from Absolute Block there is a Clearing Point and the line between the rearmost stop signal at a signalbox and the limit of that Clearing Point must not be obstructed in order for the Signalman to accept a train from the 'box in rear.  In the Absolute Block system the normal Clearing Point was for many years 440 yards but the in the 1980s it was reduced to 200 yards if the distant signal was a colour light.  Different Clearing Point distances apply in other circumstances such as in the various single line Block Regulations or Permissive Block.

 

Overlaps area term used in connection with, rightly, Track Circuit Block signalling although they have long since become more generally used in connection with most colour light signalling except when colour light signals are used as direct replacements of semaphores in systems of traditional block signalling.  Their original purpose was much the same as the Clearing Point in that they were intended to provide a safety margin in the event of a train overrunning a signal at danger and in many respects that is still basically the case.  Originally, and for many years subsequently, the standard overlap distances were 300yds for a 3 aspect signal and 200 yds for a 4 aspect signal but by the 1970s things had become much more sophisticated and overlap distances were often related to linespeed or achievable speed rather than using a simple standard - these details were set out in the Signalling Principles and of course nowadays in the various successor standards documents.

 

The term overlap has no relevance whatsoever to semaphore signalling, it belongs with colour light signals and with the various systems used nowadays don't use lineside signals.  In my view anybody who uses the term 'overlap' in conjunction with semaphore signalling needs help out of their ignorance and lack of understanding - that could well extend to some of the amateurish nonsense that emerges from RSSB.

 

As already pointed out Rule 39(a) was exactly that - a Rule and it has been in the Rule Book for many years although it long ago ceased to have that number (44 years ago in fact) and the wording has altered slightly over the years.   Rule 39, clause a, said this -

'When a stop signal is at Danger the stop signal next in rear of it and worked from the same signalbox must not be lowered for an approaching train until the train is close to such signal and has been brought quite or nearly to a stand ...'

 

This therefore applies to all stop signals applying to a particular line at a signalbox, however many there might be - a train is allowed forward from signal to signal after being brought nearly to a stand at each successive signal if those in advance of it cannot be cleared.  Nothing about overlaps, nothing about Clearing Points - both are totally irrelevant in this case; it is about the working of stop signals.

 

I trust that this will make things crystal clear and once and for all - at least on this thread - put to bed some rubbish being spluttered about overlaps in connection with semaphore signalling (and I repeat Beast gave a quote so he is definitely not included among those who have been spouting misleading nonsensical rubbish such as some of that in Post No.30).

[71000]

What on earth are you on about?  Drivers are, and always have been required to stop their train at signals at danger - and not in advance of it.  As the old saying among many Signalmen goes - "that side of it is yours (i.e. the Driver's) and this side of it is mine" - 'it' being a  stop signal.  There is no such thing as an overlap in semaphore signalling and as you might have read above it is perfectly permissible to have a  level crossing within the overlap with multiple aspect signalling.

 

The rearmost stop signal at a signalbox is the Home Signal - that is now relatively standard although it has always been GWR/WR practice to call it the Home Signal, on the LMR it would be 'Home 1' and other Railways/Regions had their own practice.

 

And I repeat - there was/is no such things as an 'overlap' in Absolute Block Signalling and there never has been and probably even in today's daft world there never will be.  And incidentally a proper Clearing Point would not exist 220 yds between an Home Signal and Inner Home Signal unless the distant signal is a colour light and It would I think be silly for the WSR not to follow usual standards in signalling.  In fact logically it might be far more sensible to have the Home Signal well in excess of 440yards in rear of the splitting Home and, ideally nowadays, provide an advanced Starting Signal at least 440yyds from the Home which would allow an engine to run round while a train is accepted from Crowcombe (or a train to be accepted while a run-round is taking place) as the South Devon have done at Buckfastleigh. 

W

[LNERGE]

I'm sure if someone had asked for a position 7 PLJI SGE would have made it. It's in their catalogue..

 

[The Stationmaster]

I'm sure if someone had asked for a position 7 PLJI SGE would have made it. It's in their catalogue..

 

IMG_0265.JPG

 

Quite logical when you think about it as the first experimental junction indicators (using fluorescent tubes of course) tested by the LNER did have a position '7' (or more likely 0 I presume) with one of the tubes mounted vertically to indicate the 'straight ahead' route.  I don't think that idea lasted very long but clearly SGE were ready to cope with it if it had lasted.  (And weren't they used on one of the 'colonial' railways?)

[uax6]

With regards to stopping trains at stop signals, you have misunderstood what I wrote, I suspect this is an "Inter-regional" terminology problem.

 

I obviously have no idea whether you were on the railways, but I guess you were never a train driver. The point is that if you are driving a large steam locomotive where the cab is 40ft or more behind the front coupling, and your sighting is obviously therefore impaired because there is a large boiler interfering with your view of the line ahead, and the fact that you have 900tons or so of unfitted freight wagons behind you, and only the steam brake on the locomotive itself to stop with. Such situations often resulted in locomotives not quite stopping exactly where they should. These problems were fully understood in those days. Therefore it was a normal requirement whether in a "Absolute Block", "Electric Token Block", "Track Circuit Block", "Permissive Block" or even "Tokenless Block" to allow a safe distance (220yds in old money) in advance of stop signals where no obstructions, such as a level crossing junctions etc existed. If some type of obstruction existed such as a level crossing or a junction, extra precautions would be required.

 

This introduces the old fashioned "track circuit" introduced about 1900 with the aid of batteries in old fashioned mechanical signalboxes. Early track circuits when used in conjunction with semaphore signalling, where often limited to short stretches (100-220yds) of line at critical locations. They could be used in conjunction with the mechanical interlocking to lock stop signals at danger, and or display a track circuit repeater light on the signalmans track diagram. Further in 1905 the LSWR introduced "Automatic Semaphore Block" in conjunction with the first "Continuous track circuits" using around 15psi air pressure to operate the signals themselves. Numerous Distant and Stop signals were automated between Esher and Worting Junction (about 35 miles apart). Here the Distants would only clear automatically when a train had passed two further Stop signals in advance. These signals were controlled by the track circuits which all had a 220yd "Overlap". More precisely each track circuit stretched from a point roughly 220yds ahead of the previous signal to 220yds ahead of the next signal. So providing the necessary minimum safe zone or "overlap" in advance of each stop signal. 

 

The point I therefore made about a steam locomotive driver stopping with the front of his locomotive in advance of a signal exhibiting a stop indication, but he the driver being 40ft or so further back not having passed the signal should now come into focus.

 

In a number of such incidences where this exact situation became apparant, the driver had to be "let off". If we now relate this problem to a level crossing only feet beyond a stop signal, with NO proper safety zone/track circuit overlap/call it what you like, in advance of the stop signal (220yds), and No Warning arrangement or other precautions, you will appreciate that the driver of a large steam locomotive is now clearly not breaking any rules if he squashes the odd car !!!

 

Obviously no one wants car drivers squashed, so adequate precautions were in the old days taken. i.e you had to have a 220yd overlap/safety zone, call it what you like, in advance of a stop signal. And any obstruction within this distance, would result in some sort of added protection such as a previous signal being held at danger.

 

The terminology relating to semaphore signal names, as per the SR, in the order they appear to a driver was as follows: 

 

Distant. Outer Home. Inner Home. Starter. Advanced Starter.

 

Not all these signals were necessarily present at all locations. And in addition it was sometimes necessary to have extra signals, such as an Advanced

Distant, and Inner Distant. (Sanderstead SR Central Division, Down line had such. It was necessary as a junction controlled by Selsdon box in rear was just within the necessary distance for Sandersteads Down Distant. Therefore there were actually two Advanced Distants one on the Down Main and one on the Down branch, slotted through Selsdons Down Main Starter or Down Branch starter. The Inner Distant was beneath Selsdons Down Advanced Starter. Sanderstead also had an Up Intermediate distant & home signal using 2 aspect colour light signals installed pre-war, at Riddlesdown station approx 2-3 miles in the rear).    

Sadly I think that it is you that is having difficulty. You seem to confuse your coloured light terminology, your AB clearing points, what you need to have clear to accept trains, and what you can and can't do in station limits.

 

As for the you saying that in steam days it was ok to pass a signal that was on by half a loco's length (sorry that's a signal displaying a red aspect just so that we are clear, I'm not sure you understand what on means) is just daft. All drivers, of whatever train, are expected to stop with the FRONT of their train before the signal. Yes there are safety zones after the signal that have to be clear before a train can be accepted upto that signal, but they are not there to be used.

 

Yes drivers pass signals at danger every now and again, and in a lot of cases in the olden days (Not now mind, you can't 'let them off' anymore) the bobby and driver would 'square it up' as there was no harm done. Doesn't mean it was right, but it did happen.

 

Andy G

[Junctionmad]

so , I think I understand this ,  In AB semaphore , we have the clearing point etc which refers to the acceptance of trains. We have rule 39(a) which controls how to move trains from signal to signal ( in the event of no clear route ) . Therefore there is no concept or NEED of an overlap, these are creatures of TCB /MAS signalling 

 

one point , where conventional track circuits where employed to aid locking , ( as opposed to TCB) did the concept of an overlap then apply  , Ive seen it mentioned that in certain cases, that a distance of 440 yards had to be clear in order to release a signal ( i.e. to off )