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Discussion Starter · #1 ·
Ok, I have been trying to fathom this for a while now and the more I look at it and try, the more confused I become.

Information:

Outside loop is the "Down" line, running clockwise.

Inside Loop is the "up" line running counter-clockwise.

The bay platforms are capable of running to either the "Up" or "Down" line (via a double slip), or continuing around to, and through, the refuge siding (third set of rails from the bottom of the track plan).

I have tried to fathom some basic signalling, although I still end up tied in mental knots trying to figure this out.

Could anyone offer advice on where I am going wrong, based on the below diagram? (signals look "odd", but are the best I can do in SCARM for lack of gantry or other signal types)

(click on the image for a larger version)

 

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Discussion Starter · #3 ·
Cheers Chris....

I stopped trying to work out the signalling at the point of the above, as I was beyond confused. It does not help when the exit / entry to the bay platforms is bi-directional either.

I am aware of the "Top to Bottom, Left to Right" descriptor, although with a couple of bi-directional sections "on the main", I forsee a forest of signals needing installation.
 

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Does the line top left continue elsewhere? Or is it a short siding?
Likewise the two lines bottom right: do they go on or act as sidings?
And what region/company and approx. time period is your layout set in? (That will affect what signals you might need.)

By the way, clicking on the picture only gives my a very modest magnification, so I can't see in any detail what signals you've already put in. But I would immediately say that the cluster of signals right of centre at the top are redundant - the protection of the crossover between the two lines would be part of the platform end ("starter") signals' functions. Keep in mind that signals would normally be spaced more than an average train length apart so that a train standing at a signal would not usually be only partly past the previous signal, where it might well be fouling pointwork and so causing a further 'jam'!

Also keep in mind that model railway distances are usually compressed compared to the prototype, and therefore the provision of signals on a model is always a compromise.
Regards,
John Webb
(St Albans South Sig Box)
 

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well as an ex signaller and now a driver i can say theres a distinct lack of distant signals by look of it and a few missing too
 

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A few questions...
When?
Where?
What company/companies?
Steam, diesel or both? (Not that this necessarily affects the signals).
Semaphore, Colour Light or a mixture?

Are there scenic breaks between the junctions/platforms and the long loops?
If so - what are they?

Signalling the long loops - nearly impossible - from a practical/modelling viewpoint.

What can be said so far...

(Ignoring the signals in the diagram because I can't get them large enough to see what they are).

Assuming this would be semaphore and basically mechanical (i.e. not power - or at least not power for everything) - you would be looking for two large framed signalboxes - one close to the junction pointwork at each end of the platforms.
  • There are two reasons for this
    1. The tracks and trains need to be in sight of the Signalmen. (The curve and length of platform impact on this).
    2. There is a legal limit to how far Facing Point Locks are from the lever working them. For mid-century (20th) and onward this would be 200 yards. Later it was increased to 350 yards - but this would only get into practice with additons or a drastic re-modelling of the track plan. Therefore essentially work with the 200yd limit. (The RH entry to the loco facilit could be an exception to this - although it could equally be on a groundframe).
    • A way around the distance limit is to use self-locking motor points... But this will not greatly alter the signalling due to the need to maintain the ability to see things from an essentially mechanical frame.
      • Two side issues apply here.
        1. The number of levers in a mechanical frame was limited in most cases after the Hull Paragon head-on crash - basically caused by the interlocking being so long that it could flex and allow a conflicting set of movements to be signalled at the same time.
        2. Depending on date - at least post WW2 - Track Circuits can be included to assist train detection and Rule 55. This would not greatly affect the exisitng signals though - but essentially improve the arrangements. There are a few earlier arrangements that could apply.

From the point of view of modelled signals I think it is best to assume that the multitude of through loops are "off scene" and that the track through the scenic break would continue for some way as plain double track.
This means a number of things:-
  • 1. For out-bound signals at each end - ignore the loops and signal as though there is only plain track ahead.
    2. Plain Distant Signals (i.e. just a Distant alone on its post) would be out beyond the scenic break and therefore we can basically ignore them.
    3. We have to imagine/assume some signals.
    4. We have to think as though the tracks are Double tracks on both end of the scenic area - more so when we think about operation and what train crew will see. (i.e. we pretend the loops aren't there).

More should follow in a freah post...
 

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QUOTE (Grifter_Guru @ 15 Sep 2014, 06:25) <{POST_SNAPBACK}>I am aware of the "Top to Bottom, Left to Right" descriptor, although with a couple of bi-directional sections "on the main", I forsee a forest of signals needing installation.

Okay - so you are saying that you are familiar with "Position Value Signalling". This is a useful start.

PVS applies to both Running Signals and Non Running Signals.
  • Running Signals = the nice big ones that can be seen at speed/from a distance by train crews - e.g. 4ft semaphore arms).
    Non-Running Signals - all the rest - all the little signals used to manage shunting and other non-running movements.

The first thing to work out is what Running Signals you are going to need. We have already decided to ignore the plain Distant Signals - so all you need to do at this stage is to work through providing the Stop Signals along each route. (Don't bother about which Box they are on for now).
Take the Down Line first - then turn yourself around and work through the Up Line. (The Bay can be done later.

Right - whichever line you are on you need a Stop Signal to protect each Fouling Point or cluster of Fouling Points that fall withing a very short distance.
  • A Fouling Point occurs where the adjacent rails of any two track come within 6 feet of each other. At a set of points and crossings this means there is a Fouling Point at both the toe end (the tips of the blades) and some distance from the heal end (the common crossing/frog end).

    This is going to mean that you need a Signal position just before you arrive at each set of Facing Points. Due to the divergence provided by Facing Points you will need an appropriate number of arms for the routes available. If there's just two routes this will mean two arms - more if there are a number of routes diverging immediately...

    You have to consider proximity to the toes of subsequent points though. (This is complicated by the compresion of model layouts). A guideline is that if there is more than a loco length (or a loco and coach length if you prefer) between the heel of a first set of points and the toe of a second - then you are potentially looking at two consecutive signal posts - with two arms each. If the distance between points is less than this you are looking at putting one signal the first position and providing an arm for each of the three routes... (I hope that is clear).

Next -
You are going to need a signal position to protect each Trailing Connection. This will be just short of the Fouling Point. (If it isn't on the approach to the FP ir doesn't protect it).
This means that you have an appropriate signal on each track approaching a convergance. For Running Signals this means that each track that comes together there will be a signal. How they are arranged (i.e. what sort of structure) will depend on the specific location.
  • Again it is necessary to deal with the proximity of subsequent Trailing Connections. A guideline would be that the distance for models would be about twice that for Facing Connections.
    This means that where there are two consecutive Trailing Connections into a line the line itself will only need one protecting signal when the connections are close enough together. Each connecting line will still need its own signal... So - where the connections are close together we get three signals - where they are further apart we would need four (two consecutively on the line being connected to).

Next -
Where A Facing Connection is followed immediately by a Trailing Connection the appropriate route signal for the facing connection can protect the subsequent trailing connection.

Next - Where a Trailing Connection is followed immediately by a Facing Connection both signals that protect the Trailing Connection will normally provide route indication for the Facing Connection - however - they will not necessarily do it in the same way.
  • Taking the Down end of the Down platforms as an example -
    The Down Through Line (through the middle) might be classed as Fast Line and signalled with 4ft Stop arms for a junction ahead... The Down Platform Loop (round the outside) might be classed as Slow Line ... this might be signalled in the same way with 4ft arms - or it might only have one 4ft arm plus a route indicator.

I think that should give you something to work on...

 

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QUOTE (Bear 1923 @ 15 Sep 2014, 15:48) <{POST_SNAPBACK}>Okay - so you are saying that you are familiar with "Position Value Signalling". This is a useful start.
etc, etc, etc.
I think that should give you something to work on...

Shouldn't you be painting or something
 

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Firstly, Thanks Bear, that helps a fair bit.
Now to answer some questions raised....
Time period: pre-group to BR, non-specific regional influence, although for signalling, midland and constituent company influence and equipment will, where possible, be used.

There are no scenic breaks.

The lines heading to bottom are provision for a future extension.

The line heading top left is a plain siding enough to hold a pacific locomotive.

Regarding signal types, I would prefer full semaphore, although depending on complexity I am willing to move to colour light signals.

Quick question, when you refer to 4ft semaphores, are you referring to Branch semaphores or main semaphores?
 

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"4ft" signal arms

The standard semaphore signal design provides both Stop and Distant arms with a blade that is 4ft long.
  • The Blade is the bit that is coloured red or yellow that is bolted onto the spectacle plate/frame and boss. The boss is the front end of the spindle which is held in the bearing that is either bolted to the signal post or through the signal post. (I think that covers that part).
In earlier periods (about 1880-1920(ish)) some lines used 5ft arms for Stop or Distant. These seem to have usually been on very tall posts. Whether they stopped being used because they caused structural issues with their extra weight and/or wind resistance or it was simply concluded that a 4ft arm was sufficient for all purposes is not recorded anywhere that I know of.

In special locations where space was limited shorter arms and/or special arms could be used. Probably the best known of these would be the GWR SB (Special Boss) arms. Where possible this arm was also a 4ft blade.

Those lines that used Somersault signals also used 4ft arms for their standard Stop and Distant signals.

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Stop and Distant Signals with 4ft or special arms in lieu of 4ft arms are Running Signals. (As above).
Running Signals are used to control Running Movements - i.e. basically train journeys.

When a Stop Signal is cleared the meaning is that the line is clear to the next Stop Signal. This includes buffer stop lamps at terminal roads.
When a Distant is cleared it means that all the Stop Signals that are interlocked with it have already been cleared and are locked by the Distant Signal's interlocking.

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"Main Lines" and "Branch Lines" are not distinctions made in the signals used. As far as signalling is concerned they are both Running Lines... the lines on which journeys are made. Therefore they bot get signalled with the same signals.
If you consider it - a train crew doing 60mph on a Branch Line needs just as much ability to see a signal as one on a Main Line. Don't forget that some lines that were classed as "branches - or called a "branch" at a junction - were very long, busy and could carry traffic at speed. They weren't all neat little rural short lines.

So - essentially - it doesn't matter what sort of line "Branch" or "Main" you are on - you will see the same signals where the purpose is the same.

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Other than 4ft arms...

Just to make life interesting and confuse modellers - but to make distinguishing signals easier for train crews on the move - the Stop Signals for some lesser lines could be shorter. They were not always different - what happened and where depends on time and place. "Lesser Line" is not a distinction between Main and Branch in this context.
Basically -
  • All Passenger Carrying Lines would be signalled with 4ft arms.
    All through Running Lines would be signalled with 4ft arms.
    Additional Lines and Running Loops would normally be signalled with 4ft arms.

    Non-Passenger Loops and large yards could be signalled with a 4ft arm or a 3ft arm - both for entry and exit- and sometimes within their length.
    Refuge exits and some siding exits could be signalled with a 4ft arm but would more usually be a 3ft arm.

A 3ft arm has the same meaning as a 4ft arm - when cleared the line is clear to the next Stop Signal. The difference in size is used to assist identification. The difference is also about the speed of the movement - whether entering or leaving a line.
The aspects of a 3ft arm will also be proportionaltely smaller.

Hopefully it will be clear from this that 3ft arms are used on much smaller/lesser lines - and also where movements are normally going to be slowing to a stop or starting from standing or have only just got moving.

A 2ft arm may also be used. A 2ft arm when cleared means "proceed prepared to stop short of any obstruction". A 2ft arm is basically used in the same way as a 3ft arm - but the speed on entry to a refuge (for example) will be much slower - probably not much above walking pace and the line may already be occupied. The speed will often be further limited by the curves in the entry points.
Where the signal going in is a 2ft arm the signal going out will usually be a 2ft arm even though the next signaql will be a 4ft arm and the line will be clear to it.

2ft arms are also used by some companies instead of ground signals. This is usually to provide better sighting of the signal. Both 2ft arms and ground signals used as "shunting signals" when cleared mean "proceed prepared to stop short of any obstruction".

That lot is the core of the subject.

There are then other uses...

Basically different companies had different ideas - and these were not always (pretty much never) consistent over time and place.

Subsiduary arms in particular could appear as 3ft or 2ft arms - but not 4ft arms.

Ringed arms - are a whole subject.

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The best thing to do is to take a look at lots and lots of pictures and work out an understanding of what seems to be used where for the company, place and period you are interested in.

I hope that lot makes sense and is useful.

 

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Aaah! You were referring to the blade only, not the blade AND spectacle plate..

I was a litlle bemused as I have a home and distant on my hallway wall, both being 5' 3" inclusive of the spectacle or 3' 5 3/4" for the enamel blade only (both Ex-BR midland region and from my home town) , I did wonder to what you were referring when you mentioned 4ft arms....

For some reason, I was always taught the term "Arm" included the blade and spectacle plate as one unit.

Despite studying innumerable photo's and books, my problem and confusions lays within, for the main part, signalling the junction between the down, up and bay platform lines, the junction between the down, up and siding lines, how to signal the north and south loco yard exits to allow loco movements to and between both up and down lines and sidings.

All this is made worse, to me at least, by the requirement for sections of bi-directional running (bi-sexual running as a railway friend puts it!) either for loco movements or, in the case of the Bay platform lines, the requirement for the "suburban" trains to traverse to or from the main lines or refuge siding in either direction.

Confusing myself is an understatement.
 

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Typical railway "complication"...

The arm is the blade but the whole combination of arm and spectacle is also referred to as "the arm". To some degree this is because for most applications (and historically) the arm and spectacle have been bolted together so that they look more-or-less one piece and cannot do anything but work together.

In a few instances, mainly sky arms - which could have 5ft arms - the spectacle was significantly lower down the post. The spectacle was still arranged to act at the same time as the arm/blade.

Other than that "difference" I don't know where the "lesson" would have come from.

 

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Discussion Starter · #13 ·
The "lesson" about signal arms was one given to my father by a signalman working a box BITD. That does not always mean the terminology was correct, but what the local (regional?) understanding was at the time most likely.
 

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QUOTE (Grifter_Guru @ 15 Sep 2014, 20:29) <{POST_SNAPBACK}>Despite studying innumerable photo's and books, my problem and confusions lays within, for the main part, signalling the junction between the down, up and bay platform lines,

This should be a double junction - but it isn't so we'll deal with it as it is...
There isn't in fact any significant difference in the signals.

The Down Line Signal for the Facing Junction needs a splitting signal - with the higher/left hand route for the main and the lower /right hand route into the bays...
It is possible that both bays would be signalled from here - depending on the length between the junction and the points to either bay. If this is short then there would be two bay signals. If it is long there would be one bay signal at the junction and another splitting signal at the points into the bays - assuming that both are used both inward and outward.
I will assume tha latter arrangement = one signal off the Down line and a splitter short of the Bays.

The Up Line only needs a signal to protect the Trailing Junction.

The bays each need a signal at the end of each platform to protect the points/trailing connection. If the distance to the junction is short there need not be a further signal - but if, as I'm assuming, the distance is longer there would be another signal protecting the trailing junction.
All these would be 4ft Stop Arms.

How the line into the bays is worked is a different matter... If it is all on one Box the opposing signals would simply be interlocked so that opposing directions could not be signalled at the same time. It is possible that there would also be an acceptance lever controlling which direction could be worked. (Red lever).

QUOTE the junction between the down, up and siding lines,

QUOTE how to signal the north and south loco yard exits to allow loco movements to and between both lines and sidings.
I would signal these moves with dummies or 2ft arms - stacked vertically - an arm for each route to the Up and Down... tasking it that the sidings are the long loops - I'll deal with that later.

QUOTE Made worse, to me at least, by the requirement for sections of bi-directional running either for loco movements or, in the case of the Bay platform lines,
I've dealt with this above. The only difference between double and single track is that all the signals are located on the one track - the signals for each direction are the same as for double track. (The need to stop and/or direct is not different).

QUOTE the requirement for the "suburban" trains to traverse to or from the main lines or refuge siding in either direction.

Confusing myself is an understatement.
This isn't clear to me.

I suggest...
Make a very large copy of the diagram between the ends of the loops at both ends - make several copies to play with. (That way you'll probably only need one).

Then put yourself in the loco cab and think yourself through each route. This should show you where you are approaching something that needs protecting and sometimes a place where direction is needed. This will give you the basic signals.
When you have the Running Signals sorted out you do the same for shunt signals.

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Signals for the sidings/loops...

If you try to signal all the routes into these I fear that it will end up looking ludicrous...

Ummm... I've just checked the diagram... As far as I can see there is no Down end exit from all the sidings to the Down Line... This must limit your use of these sidings to Up Direction running?

Looking at it it also appears that the Up and Down Lines run all the way round the outside...

I would therefore suggest that you signal this on the basis that they are through lines of the rest of the world and that the inner loops are all some variety of large marshalling yard.

This will mean that there will need to be routes signalled through the Facing Junction from the Down line and from the loco exit at this end. Running Line Signal a 4ft arm. Marshalling Yard signal - possibly a 4ft arm - much more likely a 3ft arm with a route describer.

You can get away with a signal on the Up Line protecting the Trailing Junction - this will also be the splitting signal into the loco reception - probably a 2ft arm for the loco.
The exits from the marshalling yard - I would use three posts with 2ft arms and route describers. This will make less of a forest. The track nearest the Up Line could have a 3ft arm.

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At the other end - the Down Line has no involvement with the inner loops - so that is simple. (If you have a Distant for this line it would not be a splitting Distant but just a plain Distant.

Okay - entry to the loops - treat them the same as at the other end - a spltiing signal. 4ft Stop arm for the Up line and a 3ft with describer into the loops.

--- At the moment I have no suggestions for the odd bit between the bays single line and the loops... I'd forgotten that...

It will need the signal coming out of the single line to be a splitting signal - arm to the left for the odd bit of line and an arm for the Up Line... If you want to shunt out wrong Line onto the Down to get across to the Down Platforms you will also need a 2ft arm or a dummy there for the shunt.
The exit end of this odd line will want some sort of signal as well...

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See if that lot answers some of your questions...

 

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QUOTE (Grifter_Guru @ 15 Sep 2014, 21:20) <{POST_SNAPBACK}>The "lesson" about signal arms was one given to my father by a signalman working a box BITD. That does not always mean the terminology was correct, but what the local (regional?) understanding was at the time most likely.

Huh! What do you expect if you listen to a signalman!!


By the by... If you are signalling all the sidings etc you are potentially looking at four signalboxes for the Up and Down Lines - and a whole load of slotted Distant Signals.

 

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Discussion Starter · #16 ·
Thanks bear, that has answered a fair few questions for me, so I will answer one for you.

The refuge siding and main sidings are indeed linked to the outer "down" line via a double slip at the top right hand side of the track plan, just where the "south" exit of the loco yard is. Granted, it means movement from the sidings is via a reversL move to access the down platforms, but it is there.

I will get back to the track plan and place the signals as best as I can in-line with what you hVe stated above and post the updated track-plan as soon as that is completed.

As for listening to signalmen, good point, but then to a gricer (my father), the info received was not viewed as suspect. Only with time and knowledge gained from more appropriate sources is that info challenged and/or corrected as/where deemed necessary.
 

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Discussion Starter · #18 ·
Cheers Jack, that certainly helps a great deal!!

As for the Banner repeater (Fig___ Photo of a mechanical banner repeater signal still in use in 2001) A close friend has one of these, amongst other signals, in their back garden.... Quite big up close and great for "scratching the itch" of wanting to change a signal from one, to the other, aspect.

Other than that, I have a pair of (working) 3 aspect ground (position) signals indoors myself. A great benefit for modelling the things in any accuracy. The "Working" is actually achieved by a timer and a relay set so the signals change aspect every 15 minutes automatically, however with a lever, a switch and a ten minute re-wire, it would work as intended albeit on 240v rather than 110v.
 

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Ok, Here is the updated track plan with signals in place..

I **think** I may have added signals on the Gantry where they are not required and although they make sense to me,that does not make them correct....

(Click for full resolution image)

If the linked full size image does not load, try clicking THIS LINK

 
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