Signalling for modellers who don't know much about signalling

[phil-b259]

 

typical station.png

 

In this example the Distant signals (1 and 13) can only be set of 'off' when stop signals 2 & 3 and 12 & 11 are also 'off' with such a restriction being built into the lever locking.

 

To show difference compared to semaphore signalling principles, were this layout being signalled using coulor light principles  (and I acept that the distances would change etc), signal 1 could show a green even if signal 3 was at red (with signal 2 showing yellow).

[Andy Hayter]

Just a couple of questions concerning the diagram in post 34.

 

The implication is that the UP platform is "in section" and not within station limits. Does that mean that any train stopping would have to be belled as "requiring to stop in section"?

 

What in the relevance of the "Train Length" between points 9 and the UP Section signal? I fail to see what relevance points in a siding has to do with the Section signal.

 

 On the last point, it ensures that a train held at signal 3 is clear of the single slip 9&7.  This means that even if a train is held at signal 3, a route can be set up through 9,7,9,7 and the ground signal 10 can be set without fear of a train in the sidings then hitting the end of  train held at signal 3.   If that makes sense.

[The Stationmaster]

Just a couple of questions concerning the diagram in post 34.

 

The implication is that the UP platform is "in section" and not within station limits. Does that mean that any train stopping would have to be belled as "requiring to stop in section"?

 

What in the relevance of the "Train Length" between points 9 and the UP Section signal? I fail to see what relevance points in a siding has to do with the Section signal.

 

This is possibly where starting from the wrong place and using a simple example which can be anything but, will get us - and it's also why the subject is probably rather difficult to deal with from the ground up (or from the absolute basics) when put into a thread like this.

 

Taking your specific questions and dealing with them at the basic simplest level - Yes the Up platform is indeed in the Block Section but that is not really of any particular relevance except when it comes to shunting on the Up line.  Plenty of stations sat within block sections and trains stopped at them and were signalled in the normal way (requiring to stop in section is a rather different thing from a train making a booked stop at a station in a block section.

 

Anda s others have already said your second point is spot on there is no relevance in respect of train length to the distance between the point and the Section signal although in a very purest situation it would save some bell signals and under LNER Block Regulations it would have allowed a train of that length to shunt that siding.

 

But think now how far we have got into terminology and methods of working just through two very straightforward questions.  Back to my point about starting from the right place - which might well bore many readers? - in order to make sense of what comes later as knowledge is developed.  some people reading this thread might no have a clue about the meaning and significance of some of the terminology  terminology you and I have just used while others would lap it up and probably start pointing to contrary examples.  In  the model railway world such terms might be considered irrelevant but of course they aren't IF you wish to operate in a prototypical manner.

 

Now look at this sketch from my manuscript - it shows only one line, in one direction, between three successive signalboxes and illustrates that a Block Section runs from the most advanced stop signal (the Section Signal) at the 'box in rear (A in the first instance) to the rearmost stop signal (the Home Signal) at the next signalbox in advance (B in the first example) and then does the same between B and C.  We immediately get an idea of what a block section is and also come across the names used to describe the function of two different stop signals at a particular signalbox.

 

We can look a bit further and see that at B the section of line between the Home Signal and the Section Signal is called Station Limits (which has nothing at all to do with the presence or otherwise of a station).  This should prompt further questions especially why do these two bits of railway have different names?  Simples - they have two different sets of operational conditions applicable to them, basically a train running into a block section needs the co-operative action of two Signalmen to get permission to do so and it must then enter and leave the section at the correct ends of that section, can only run through it from one end to the other in the right direction.  However in Station Limits a train, or a shunt, can run in either direction doesn't necessarily require a brakevan (in the days when such were required) and can attach or detach vehicles - i.e you can do shunting movements in Station Limits (among other things).

 

If you've bothered to read this far - and this is where the internet problem comes in because in a book you could skip this and leap forward to another bit which you think is relevant to you and then find you really ought to have read this first - but if you have read and thought about things you now know some of the badsic things about Block sections, Station Limits, that a Home Signal is actually a signal with a specific function and not some sort of generic term (that is 'stop signal') and so on.  And thus far, although they're sketched in, the distant signals are more or less irrelevant.

 

Edited August 31, 2017 by The Stationmaster

[The Stationmaster]

 On the last point, it ensures that a train held at signal 3 is clear of the single slip 9&7.  This means that even if a train is held at signal 3, a route can be set up through 9,7,9,7 and the ground signal 10 can be set without fear of a train in the sidings then hitting the end of  train held at signal 3.   If that makes sense.

 

Provided signal 3 is maintained at danger.  And once the route you mention is set up signal 3 will be locked at danger potentially delaying any train waiting at it

[Colin_McLeod]

The OP is to be congratulated for attempting a simple guide to signalling a MODEL railway.

 

May I suggest the Peco shows you how book called "signalling tne layout".

 

PS I calculate 440 yards as 17'4" in OO and not 50'

[beast66606]

May I suggest the Peco shows you how book called "signalling tne layout".

 

At least one edition of which has the immortal line "On single lines, distants signals are fixed in the off position" - or similar but the jist is that.

[peanuts]

Just a couple of questions concerning the diagram in post 34.

 

The implication is that the UP platform is "in section" and not within station limits. Does that mean that any train stopping would have to be belled as "requiring to stop in section"?

 

What in the relevance of the "Train Length" between points 9 and the UP Section signal? I fail to see what relevance points in a siding has to do with the Section signal.

question one no train required to stop in section usualy aplied where the train would stop to shunt into an intermediate siding/groundframe 

question two is to avoid the need to "shunt into forward section" to clear said point with the longest train tho i do think the measurment point would be from the up end of points seven 

[Clive Mortimore]

question one no train required to stop in section usualy aplied where the train would stop to shunt into an intermediate siding/groundframe 

question two is to avoid the need to "shunt into forward section" to clear said point with the longest train tho i do think the measurment point would be from the up end of points seven 

Hi Peanuts

 

As I only coloured the signals from a diagram I scanned from a very useful book, all I can suggest is the person drawing the diagram has taken into account the wagons on the rails. Should a wagon be travelling across the points marked number 9 at a point about half way across from the siding to the main line it would start to take physical space in the loading gauge of the mainline. A potential bump. Therefore placing the signal a few yards further along the risk of a bang happening to the rear of the train is hopefully eliminated.   

[Junctionmad]

While I understand the focus on block working , as this is the origin of the signalling requirement. It's something, I think , most modellers understand " in general " the principles behind things like " absolute block " etc, but very few have any detailed knowledge and even less implement any form of block system. A visit to any exhibition will see most layouts ignore signals by and large

 

In that regard many layouts are often improbable track configurations, not easily lending themselves to prototype signalling, but many modellers still add working signals to such layouts ( hence the requests here on this forum etc ).

 

Hence the subtleties of block and station limits , blocking back, shunting into forward section , etc are largely lost on this type of layout and its operator

 

what I found had is this type of modeller would like to add " stop " signals to add more realism. Hence the desire to position such stop signals around the layout in some form of prototypical semblance and to avoid obvious " howlers " , like signals situated in advance of points they are protecting etc !! ( or siting stop signals where a train so stoped would actually foul the adjacent line etc !! )

 

I use the term " stop " signal specifically, because in reality starters and homes etc have no role on the majority of model layouts. There is no " section " or " limits "

 

So guidance at this level is aimed at showing such modellers how " stop" signals are typically placed, the assumption also is little or no interlocking will exist, other then the operator hopefully replacing stop signals to retain a semblance of prototypical behaviour.

 

Discussions about distants, clearance, real life siting distances , obscure regional working practices etc are fine and dandy when signalling aficionados get together, we can blather on all day etc. , but this is all " lost" to the average modeller , even one that has an " interest " in signalling

 

I make no comment on the accuracy of the OPs post , but I understand what he's trying to do and the audience he's trying to address.

Edited September 1, 2017 by Junctionmad

[PaulRhB]

Starting signals are the most common found on a model as they control starting from a station

Home signals are often off scene on a small BLT but appropriate for many home roundy layouts. On a larger linear layout with a couple of stations the Home signal is useful to hold trains outside as shunting takes time but the distance between stations is so compressed that the next train often gets there too fast.

Compromise is inevitable and many just want trains in a nice setting so don't have the time to study trackplans and signals because it's not part of their reason to have trains.

Both sides can sit happily together just by recognising it

On my OO layout I have a working Starter and a load of cast ground signals that look right but don't operate, I accept that as they are hard to see anyway and they give the impression until I maybe get around to making up etch working ones. The Home signal is printed on card in the Fiddleyard to remind operators to shunt behind it, not just stop on the station throat, at shows

[Colin_McLeod]

How is this for a possible guide:

 

1)Stop signals at platforms.

 

2) A stop signal on the approach to the station. If there is more than one route a train can take (e.g. a second platform) then make this a junction signal (generally one arm for each route)

 

3) If your approaching track is long enough provide a distant signal.

[The Stationmaster]

How is this for a possible guide:

 

1)Stop signals at platforms.

 

Maybe - but not essential as it depends on the track layout and how it is intended to be worked  (be it real world or a model)

2) A stop signal on the approach to the station. If there is more than one route a train can take (e.g. a second platform) then make this a junction signal (generally one arm for each route)

 

Quite likely but maybe nowhere in sight of the platform on some double line layouts (otherwise it wouldn't be much use).  the only difference would be if there are facing points involved which would need a splitting signal more or less at the point toe

3) If your approaching track is long enough provide a distant signal.

 

Only if you can manage some sort of scenic break to 'isolate' the distant signal or it is an old and very low speed branch line where the distant might only be a few hundred yards in rear of the Home Signal  (but still no doubt something like 17 feet or much more in 4mm scale)

[imt]

Provided signal 3 is maintained at danger.  And once the route you mention is set up signal 3 will be locked at danger potentially delaying any train waiting at it

 

Sorry to be asking questions from a few posts back.

 

Mike, please bear with me, but I don't understand that one.  I understand that in the "typical station layout" that the Block Section/Station Limits for this Block Post run from signal 2 to 3 UP and from 12 to 11 Down.  I quite understand that railway signals are not traffic lights, so a train running to WTT may stop at a passenger platform for passengers to alight/join regardless of what signals are there and where the platform might be in a Section, and that because a signal at or near the end of a platform is "clear" it merely means that the line ahead has been set clear in conjunction with the box ahead and does not mean that a train due to stop should simply pass through the station.  This is emphasized by the down platform where the signal is considerably in advance of the marked passenger platform end.

 

SO we now have the situation that an UP train which has been accepted into the Block after passengers have alighted etc. has been held at signal 3 because clearance has not been obtained from the Block Post ahead.  I presume this would be in order, since that move into this block (station limits) would allow the preceding block to be cleared for a following train. It was being suggested that a shunting move could take place from the Up yard to the Down line as controlled by ground signal 10 whilst this train was held at 3.  You said this would be OK BUT that signal 3 would be locked by that move, and would be unable to be released until the shunt move was complete (and points/signals reset).

 

NOW I can understand that 2 would be locked since any approaching train would otherwise run into the shunting move (or move off from the platform into the shunting move).  But why 3? It would only be cleared when the next block was clear.  Or is it the case that a train would not be accepted into this block unless the next block were clear - hence both 3 and then 2 would be cleared, so the train would rest at the platform when there had been no acceptance from the block ahead.

 

I am running to get behind the sofa right now .............!

[Compound2632]

Was it actually permissible for the signalman to accept a train into section if he couldn't clear his signals for it? - i.e. if there was shunting blocking the line within station limits? Sounds dicey to me. I recall (i.e. haven't checked) a BoT Inspector's report quoted in Red for Danger in which the block system as worked by the Midland (c. 1880s?) was criticised for reducing the margin of safety to the thickness of the signal-post. I'd not understood that but perhaps this situation is what is being referred to.

[micknich2003]

Was it actually permissible for the signalman to accept a train into section if he couldn't clear his signals for it? - i.e. if there was shunting blocking the line within station limits? Sounds dicey to me. I recall (i.e. haven't checked) a BoT Inspector's report quoted in Red for Danger in which the block system as worked by the Midland (c. 1880s?) was criticised for reducing the margin of safety to the thickness of the signal-post. I'd not understood that but perhaps this situation is what is being referred to.

Basicly yes, but only provided the line in advance of the first stop signal was clear for 440 yards.

[Compound2632]

Basicly yes, but only provided the line ahead of the signal was clear for 440 yards.

 

... which for many (most?) cases would be pretty much station limits, so: in theory, yes; in practice, no?

[imt]

Was it actually permissible for the signalman to accept a train into section if he couldn't clear his signals for it? - i.e. if there was shunting blocking the line within station limits? Sounds dicey to me. I recall (i.e. haven't checked) a BoT Inspector's report quoted in Red for Danger in which the block system as worked by the Midland (c. 1880s?) was criticised for reducing the margin of safety to the thickness of the signal-post. I'd not understood that but perhaps this situation is what is being referred to.

 

The shunt was not actually blocking the line at the time the train was accepted past the Home signal up to the Section signal.  The train is now standing at signal 3 (Section signal) and the shunt is taking place across its rear (which is why the distance from the safe overlap to the Section signal must be > the length of the longest train) but protected by the (locked) Home signal.

 

Mike said that if the shunt were to take place, then the Section signal would be locked.  I said I could understand the Home signal being locked but not the Section signal. 

[micknich2003]

... which for many (most?) cases would be pretty much station limits, so: in theory, yes; in practice, no?

The attached may help to explain.

[RailWest]

To quote from some preceding posts.....

 

"I use the term " stop " signal specifically, because in reality starters and homes etc have no role on the majority of model layouts. There is no " section " or " limits "...."

 

"Starting signals are the most common found on a model as they control starting from a station ..."

 

Sorry chaps, but no. Once again, it depends upon the railway in question, but if you look at the GWR or (to a lesser extent) the SR, then the terms 'Home' and 'Starter' - and the variations thereof - relate to the position of the signal relative to the controlling signal-box. So, in the example diagram 2 is a Home, even though in effect it controls 'starting' from the station. Most models do have 'station limits' which exist within the modelled area, with the start/end of the 'block sections' often - but not always - being within the visible modelled area.

 

>>>It was being suggested that a shunting move could take place from the Up yard to the Down line as controlled by ground signal 10 whilst this train was held at 3.  You said this would be OK BUT that signal 3 would be locked by that move, and would be unable to be released until the shunt move was complete (and points/signals reset). Now I can understand that 2 would be locked since any approaching train would otherwise run into the shunting move (or move off from the platform into the shunting move).  But why 3?  It would only be cleared when the next block was clear" 

 

Quite simple...one of the basic rules of interlocking would require that clearance of signal 3 would lock points 7 (and hence points 9, which would be released by 7) in which ever position they were at the time - either normal or reverse (known as 'both ways' locking) to ensure that the points are not moved under any train that moves off once 3 is cleared. Therefore, because mechanical interlocking is reciprocal, reversing 7 would lock 3. Furthermore, 3 and 10 would be required to lock each other because they control opposing moves - otherwise, if you could (accidentally) pull off both 3 and 10 at the same time, which way is the train supposed to go ??? :-) It's nothing at all to do with the state of the block section in advance of 3.

[Compound2632]

The attached may help to explain.

BTR 4.jpg

 

So, my understanding of this is, if. the line being clear for 440 yd beyond the home signal, a train has been accepted from the box in rear, no shunting can occur on this line with the station limits - because all the points are locked (4a). However, if the train has been brought to a stand at the home signal, a shunt manoeuver could then take place on the line ahead of it (4c.i. and whatever is on the next page).  

 

I also not that often the home signal is in rear of the station platform (unlike the up home diagram in post #34), so it would be unusual to be able to bring a passenger train to a stand at the platform and then shunt in front of it. The passenger train doing its own shunting - e.g. detaching a horsebox - is a different matter, as it's within station limits. In fact the layout in post #34 would be inconvenient, as to detach a vehicle and put it in either the up or down siding, the up home would have to be pulled off. That's quite apart from the lack of a direct trailing connection into the up siding.

 

In fact, for a model of such a wayside station on a continuous-run main line, very few signals would be needed. The distants are certainly off-stage, probably the starters (3, 11) too - especially if either siding is a lay-by. If there's a bridge as a scenic brake at the LH end of the station platforms, the up home (2) might be off-stage too.

 

On the other hand, an urban continuous layout run could well represent a section of line with short block sections and distants on every post slotted back from several boxes in advance... Then the important thing to remember, if I've understood correctly, is that the distant cannot come off if the signal above it (home or starter) is on, but one might see both come off together - at least for an approaching express; local traffic is unlikely to be so lucky! Such a layout would have a goods line in at least one direction, worked under permissive block, so one can have the engine of one mineral rain cautiously creeping up on the brake van of another... That would make for really atmospheric operation. (Especially with scale fog.) Terry Essery's Saltley Firing Days is one of my favourite railway books!

 

My point is, even if the signals are off-stage, one should operate believing in their existence.

Edited September 1, 2017 by Compound2632

[RailWest]

>>>I also note that often the home signal is in rear of the station platform (unlike the up home diagram in post #34), so it would be unusual to be able to bring a passenger train to a stand at the platform and then shunt in front of it.

 

I don't see why. If there was a Home in rear of the one shown on the diagram as No 2 (ie before the train arrived at the platform), then you could apply Rule 39(a) and allow the train to draw past it up to No 2 (which would be kept 'on'). Once the train was a stand there, no reason not to shunt across 7/9 if necessary.

 

>>>The passenger train doing its own shunting - e.g. detaching a horsebox - is a different matter, as it's within station limits.

In the diagram as shown, once the train was past 2 then it would indeed be within station limits. Whether it shunts, or another engine does the shunting, I don't see why you consider it a 'different matter'.

 

>>>In fact the layout in post #34 would be inconvenient, as to detach a vehicle and put it in either the up or down siding, the up home would have to be pulled off.

So? Why would that be inconvenient?

 

>>>My point is, even if the signals are off-stage, one should operate believing in their existence.

 

I agree completely !! :-):-)

Edited September 1, 2017 by RailWest

[Compound2632]

>>>I also note that often the home signal is in rear of the station platform (unlike the up home diagram in post #34), so it would be unusual to be able to bring a passenger train to a stand at the platform and then shunt in front of it.

 

I don't see why. If there was a Home in rear of the one shown on the diagram as No 2 (ie before the train arrived at the platform), then you could apply Rule 39(a) and allow the train to draw past it up to No 2 (which would be kept 'on'). Once the train was a stand there, no reason not to shunt across 7/9 if necessary.

 

>>>The passenger train doing its own shunting - e.g. detaching a horsebox - is a different matter, as it's within station limits.

In the diagram as shown, once the train was past 2 then it would indeed be within station limits. Whether it shunts, or another engine does the shunting, I don't see why you consider it a 'different matter'.

 

>>>In fact the layout in post #34 would be inconvenient, as to detach a vehicle and put it in either the up or down siding, the up home would have to be pulled off.

So? Why would that be inconvenient?

 

>>>My point is, even if the signals are off-stage, one should operate believing in their existence.

 

I agree completely !! :-):-)

 

I meant, rather than being positioned where it is in the diagram in post #34, the up home (2) is often to be found further in the rear, such that the up platform is within station limits. I didn't intend to refer to an additional signal (an outer home, I think it would be called). 

 

Why would it be inconvenient to have to pull 2 off to shunt a horsebox? I've no practical experience; perhaps someone with experience of working a box could explain...

Edited September 1, 2017 by Compound2632

[PaulRhB]

All stations relied on the Signalman busily operating the points and signals for shunts, they still do

When we do a run round at Salisbury I have less controls to move because of the electronics doing a lot of the work but on the ground all that happens as it did in manual days, albeit a little faster as several points can move at once.

When I was at Wool we ran round the sand train and split it to put it in the sidings that involved operating the level crossing, two starters, three crossovers and four ground signals. It's just part of the job. It's not inefficient because that's what the Signalman is there for and just keeps him busy for a bit. The modern version operated from a panel, since 2012, requires the Signalmans attention for just as long because he no longer has the audio cues of hearing the loco move so has to watch the panel more closely but presses buttons about 12 times.

The way a station operates has a big effect on what signals are used and where.

It sounds hard but a book or properly built website just presents the info better because you can deal with it in sequence. It's not that complicated there's just a lot of it and once it gets split up by other posts mentioning alternatives, corrections and general comments it's very hard to piece it together.

Even Simon who works with it and is trying to do the same in book form has pages of discussion on what works and how it might go. We aren't trying to be difficult

 

 

Here's what I did for my small terminus based loosely on Swanage. The top left line is a goods line to the Camp and Clay works, worked by a staff.

 

The only point not controlled from the box is the one in the sidings at the bottom.

Edited September 1, 2017 by PaulRhB

[Compound2632]

All stations relied on the Signalman busily operating the points and signals for shunts, they still do

When we do a run round at Salisbury I have less controls to move because of the electronics doing a lot of the work but on the ground all that happens as it did in manual days, albeit a little faster as several points can move at once.

When I was at Wool we ran round the sand train and split it to put it in the sidings that involved operating the level crossing, two starters, three crossovers and four ground signals. It's just part of the job. It's not inefficient because that's what the Signalman is there for and just keeps him busy for a bit. The modern version operated from a panel, since 2012, requires the Signalmans attention for just as long because he no longer has the audio cues of hearing the loco move so has to watch the panel more closely but presses buttons about 12 times.

The way a station operates has a big effect on what signals are used and where.

It sounds hard but a book or properly built website just presents the info better because you can deal with it in sequence. It's not that complicated there's just a lot of it and once it gets split up by other posts mentioning alternatives, corrections and general comments it's very hard to piece it together.

Even Simon who works with it and is trying to do the same in book form has pages of discussion on what works and how it might go. We aren't trying to be difficult

 

 

Here's what I did for my small terminus based loosely on Swanage. The top left line is a goods line to the Camp and Clay works, worked by a staff.

IMG_9453.JPG

 

The only point not controlled from the box is the one in the sidings at the bottom.

 

Ah, now your layout has a signal for every move. As I understand it, in many places such extravagance was avoided and all shunting was done by hand signals within station limits - no ground signals. Hence my remark about that up home signal. I have in mind the classic Midland wayside station layout, of which Monsal Dale is a nice simple example.

[beast66606]

I meant, rather than being positioned where it is in the diagram in post #34, the up home (2) is often to be found further in the rear, such that the up platform is within station limits. I didn't intend to refer to an additional signal (an outer home, I think it would be called). 

 

 

Hundreds of examples where the home (on one line) is after the platform - don't confuse a station with station limits.