Bi-Directional Signalling - single track 'avoiding / link line'

[bill badger]

Been trying to google may way through this query, but not having much joy.

 

I'm looking to place signals along a stretch of single track, envisaged to be part of a wider mainline junction / depot access arrangement, acting as an avoiding or link line that could be used in both directions.

 

Admittedly, this is a bit of a construct to allow me to run trains in either direction along a single line located at the back of a TMD layout. The layout is set in the 1980s / early 90s.

 

I want to place two colour aspect signals (4 aspect for a mainline system), one for each direction, on the basis the line is fully bidirectional. Would it be normal for signals to be paired and located immediately adjacent, or can they be offset?

 

Could someone also recommend a book / link that will give me a steer on where lineside equipment (boxes etc.) would typically be located in relation to signals.

 

Thanks.

Edited September 28, 2018 by bill badger

[iands]

Been trying to google may way through this query, but not having much joy.

 

I'm looking to place signals along a stretch of single track, envisaged to be part of a wider mainline junction / depot access arrangement, acting as an avoiding or link line that could be used in both directions.

 

Admittedly, this is a bit of a construct to allow me to run trains in either direction along a single line located at the back of a TMD layout. The layout is set in the 1980s / early 90s.

 

I want to place two colour aspect signals (4 aspect for a mainline system), one for each direction, on the basis the line is fully bidirectional. Would it be normal for signals to be paired and located immediately adjacent, or can they be offset?

 

Could someone also recommend a book / link that will give me a steer on where lineside equipment (boxes etc.) would typically be located in relation to signals.

 

Thanks.

Hi Bill,

 

It would be helpful if you could provide a sketch of the layout. This will enable people to comment/advise more accurately on what you are endeavouring to achieve.

 

As for the Loc's, for the period you are enquiring about, typically they are located adjacent to signals, points, etc., but on occasions they are provided seemingly in the middle of nowhere and not near any equipment, just acting as cable termination cabinets and/or housing repeater equipment.

[Fat Controller]

Hi Bill,

 

It would be helpful if you could provide a sketch of the layout. This will enable people to comment/advise more accurately on what you are endeavouring to achieve.

 

As for the Loc's, for the period you are enquiring about, typically they are located adjacent to signals, points, etc., but on occasions they are provided seemingly in the middle of nowhere and not near any equipment, just acting as cable termination cabinets and/or housing repeater equipment.

Landore depot, Swansea, has an arrangement of this type. The chord on the western side, which joins the double track line from Cardiff to Swansea, and the one from Swansea towards Carmarthen, is single line, but bi-directional. I recollect there is simply a signal protecting the exit from the chord at either end. The two signals are just about evident in the Google Earth view, but the TPWS grids in the 4-foot are quite clear:-

https://www.google.co.uk/maps/place/Landore,+Swansea/@51.6405238,-3.941494,401m/data=!3m1!1e3!4m5!3m4!1s0x486ef567eb8bbaef:0xb5e733596972af9e!8m2!3d51.6412925!4d-3.9369162?hl=en

[28XX]

The signals would not be paired deliberately. There would be an entry signal at each end, and possibly an intermediate signal for each direction, to allow two trains to follow each other in the same direction. The positioning of these will depend on visibility, gradients, speed restrictions etc. as applicable in the direction of travel.

 

With colour light signals, its probably track circuit block, (no tokens). The location cabinets are likely to be adjacent to signals or at the start/end of track circuits. If cable joints are needed, they can be entirely sealed in a cable joint in the troughing run, no need for a loc.

 

I feel 4 aspect would be unlikely in the scenario you paint. Watch someone come back with a prototype though!

Edited September 28, 2018 by 28XX

[phil-b259]

 

 

I want to place two colour aspect signals (4 aspect for a mainline system), one for each direction, on the basis the line is fully bidirectional. Would it be normal for signals to be paired and located immediately adjacent, or can they be offset?

 

And this statement shows you have little desire to follow reality.

 

Signalling is expensive and signals do not get placed where people 'want' them to be, they are put there on the basis of operational need. Far too many modellers seem to have a desire to festoon their layouts with coloured lights as if it were a Christmas tree when, if you want to be realistic, the phrase 'less is more' comes to mind

 

Thus if your single running line is intended to depict the '3rd side of a triangle setup', it is extremely rare for lots of trains to follow each other nose to tail (if that were the case then the line in question would be double track anyway) so you only require 2 signals, not 4.

 

Four aspects on the other hand is quite possible - if the two main lines the chord connects to at each end has 4 aspect signalling, then so will that giving permission to exit the chord.

 

An example (although 3 aspect and not featuring a depot) can be found here:- https://www.flickr.com/photos/mark_milham/5078640637

 

A further example can be found here at Hither Green - although the chord in question (the Lee spur) is double track please note there is only an exit signal at each end, not an entry one. (Scroll to page 14 of 16) http://www.signallingnotices.org.uk/scans/2360/2360.pdf

Edited September 28, 2018 by phil-b259

[RailWest]

IIRC - but I stand to be corrected - the reinstated Laverstock curve at Salisbury had/has entry signals only - to enter the line at either end it had to be clear all the way through out onto the main line at the far end.

 

As mentioned above, a plan would be useful.....:-)

[phil-b259]

IIRC - but I stand to be corrected - the reinstated Laverstock curve at Salisbury had/has entry signals only - to enter the line at either end it had to be clear all the way through out onto the main line at the far end.

 

As mentioned above, a plan would be useful.....:-)

 

As you say the Laverstock loop has no signals on it at all!

 

See here for a photo of the relevant section of Salisbury panel http://photos.signalling.org/picture?/3018/category/2418-2010_may

 

This is probably due to the potential of trains stalling on the sharp curve / gradient - although if there is no operational need to hold a train on the curve anyway then then not providing any signals will produce a significant cost saving.

Edited September 28, 2018 by phil-b259

[The Stationmaster]

As you say the Laverstock loop has no signals on it at all!

 

See here for a photo of the relevant section of Salisbury panel http://photos.signalling.org/picture?/3018/category/2418-2010_may

 

This is probably due to the potential of trains stalling on the sharp curve / gradient - although if there is no operational need to hold a train on the curve anyway then then not providing any signals will produce a significant cost saving.

 

Hardly long enough to provide signals - it's only 28 chains between the point ends so less than 600 yards between fouling points and by the time you put signals in with any sort of realistic overlap you wouldn't be able to hold much more than a 3/4 coach train in clear.  So not much use for standing the container trains that it was provided for.   No doubt at times a nuisance (our 'resident' from the area can no doubt tell us?) but it looks to me like it was signalled to do the job it was provided to do.

[Jim Martin]

As you say the Laverstock loop has no signals on it at all!

 

See here for a photo of the relevant section of Salisbury panel http://photos.signalling.org/picture?/3018/category/2418-2010_may

 

This is probably due to the potential of trains stalling on the sharp curve / gradient - although if there is no operational need to hold a train on the curve anyway then then not providing any signals will produce a significant cost saving.

Do the colours on that panel signify anything, or are they just to differentiate one track section from the next?

 

Jim

[Grovenor]

Do the colours on that panel signify anything, or are they just to differentiate one track section from the next?

 

Jim

Just to differentiate as you suggest, the colours, green/brown on one track and yellow/blue on the other originated oin the BR signalling principles in the early 1960s. Ignored as usual by the WR who didn't see the point and just had them all black.

Regards

Edited September 29, 2018 by Grovenor

[bill badger]

Thanks for the replies.

 

As requested, here's my plan (thread linked in signature). Signals as 'plonked' in Anyrail are just for show. I'm after feel of a prototype that might be reasonable.

 

 

The rear line is included almost as part of the backscene, so I can place (& run when set up with enough space) 'mainline' trains. The whole layout is intended to be a limited view of much wider local infrastructure - a TMD alongside a mainline.

 

The thinking was to represent some sort of avoiding line (crewe hole style), part of the mainline system with further lines beyond. This line would leading to the (off scene) depot entrance / yards etc. Granted 4 aspect & full bi-directional might be pushing it.

[Grovenor]

To make a sensible signalling proposal we need to have the plan showing what is supposed to happen off scene in either direction, otherwise you mayv as just put them wherever you think they look OK.

Regards

[RailWest]

>>>Signals as 'plonked' in Anyrail are just for show.....

 

I see no signals (Horatio Nelson) :-)

 

Simply on the basis of that plan alone, frankly I see no need for any signals anywhere.

[Edwin_m]

The way the tracks converge at the left suggests that they may join not too far "off scene", so you could credibly have a signal at/near the left hand end of the layout protecting that junction for trains going right to left.  On the other hand the "half a shed" at the right hand end suggests that the junction at that end may be quite a bit further away, so the protecting signal in that direction might also be "off scene". 

 

The type of signal depends on how busy the line is that the trains are joining (the imaginary main line off the left hand end of the layout).  It doesn't depend on the frequency of trains using the visible link.  So very busy would be a four-aspect signal, less busy a three-aspect (probably the most likely).  A 2-aspect red/green is also possible but only for a very quiet main line with no more signals for a couple of miles or more. 

Edited October 1, 2018 by Edwin_m

[bill badger]

>>>Signals as 'plonked' in Anyrail are just for show.....

 

I see no signals (Horatio Nelson) :-)

 

Simply on the basis of that plan alone, frankly I see no need for any signals anywhere.

 

Odd - doesn't look like they have been 'exported' by Anyrail.

 

Thanks for everyone's responses; I appreciate the slightly 'woolly' nature of the scenario and take on board the comments. The concept is to provide as much interest as possible within a limited space, within my brief to create a partial view of 1980s TMD in N gauge. I thought it would increase interest to include the means for slowing / stopping passing trains and for movements across the back to then appear 'on depot'. The rear line is best conceived as a loop, avoiding line (as per Crewe) or even a 'slow' running line in a main line system. Depot access is some way to the left, and the main bulk of the TMD extends to the right. I daresay there would be a yard in proximity.

 

Whilst I acknowledge comments about the need for signals and the 'reality' of the undertaking, surely everything we try to do in the modelling world is all about feel and interpretation? If we modelled to 100% real life accuracy our layout  would generally be very dull watching indeed. Hence my query about the theory of signalling a bi-directional stretch of busy line; I think I can now plan accordingly.

[phil-b259]

Just to differentiate as you suggest, the colours, green/brown on one track and yellow/blue on the other originated oin the BR signalling principles in the early 1960s. Ignored as usual by the WR who didn't see the point and just had them all black.

Regards

 

Black is used to represent non track circuited lines! - nothing to do with any 'Western region practice'. Moreover the colouring in of track sections pre-dates BR I believe.

 

Usually up lines (carrying traffic towards London) are yellow & blue - which makes sense as in what do you see if you look up? (blue sky and yellow sun)

 

Down lines usually use brown & green - again makes sense if you look down at the ground.

 

Purple is used these days where an extra track circuit has been added and to save re-colouring the entire diagram.

 

Black is used for non track circuited lines.

 

Single track track circuited lines can use either the yellow / blue or brown / green colours - though the exact setup will usually depend on the box location (e.g. 'up colours heading away from the box towards London and brown / green heading the opposite way

[RailWest]

Just as an aside, but... a question to which I have never been able to find an answer, if indeed there is one other than simply "take your pick", is....

 

On an 'illuminated' diagram for a double-track line where there is just one TC on the Up line and one TC on the down line (I've seen that sort of thing), which colour do you use from each pair? Is there a default 'first colour to use' or do you indeed just make your own choice?

[phil-b259]

Odd - doesn't look like they have been 'exported' by Anyrail.

 

Whilst I acknowledge comments about the need for signals and the 'reality' of the undertaking, surely everything we try to do in the modelling world is all about feel and interpretation? If we modelled to 100% real life accuracy our layout would generally be very dull watching indeed. Hence my query about the theory of signalling a bi-directional stretch of busy line; I think I can now plan accordingly.

Nothing wrong about invoking ‘rule 1’ to provide a more interesting layout to operate - providing you are fully awere of what you are doing is not as per prototype and acknowledge the fact.

 

This is mportant to ensure others who wish to be mor accurate are not led astray should they want to accurately reflect prototype practice when it comes to signaling.

 

Also have you looked at Cardiff Canton depot when speaking inspiration as this features a double track ‘3rd leg of a triangle’ on its southern side.

Edited October 2, 2018 by phil-b259

[Grovenor]

Black is used to represent non track circuited lines! - nothing to do with any 'Western region practice

Perhaps you should check the WR standard Henry Williams domino panels before you contradict me. And see IRSE News October 2018 page 25.

 

The colours may predate BR but they were specified for panels in the BR standard signalling principles.

 

Regards

[bill badger]

Decided to go with a single signal covering normal running from right to left and forget the reversible or bi-directional idea. Think it would add interest to include direction feathers to indicate a junction beyond.

[TheSignalEngineer]

The GWR didn't colour track circuits on its signal box diagrams. In the 1930s through to early BR days popular colours seemed to be passenger running lines light grey, sidings and crossovers signalled for shunt moves only  were light blue and (IIRC) goods running lines were sometimes light tan. Track circuited lines were black, the demarcation between them being a white space. A caveat to this is that I have seen a WR diagram with the sidings in light tan and running lines in light blue, another with passenger lines grey, goods lines light blue, sidings light tan and track circuits denoted by a line down the middle of the track, and another with goods lines in light tan and sidings in light blue.

[phil-b259]

Perhaps you should check the WR standard Henry Williams domino panels before you contradict me. And see IRSE News October 2018 page 25.

 

The colours may predate BR but they were specified for panels in the BR standard signalling principles.

 

Regards

Perhaps you should consider that not everywhere has WR standard Henrey Williams Domino Pannel’s before attempting to belittle others.

[Wheatley]

Perhaps you should consider that not everywhere has WR standard Henrey Williams Domino Pannel’s before attempting to belittle others.

 

But the WR does. Are any of your examples on the WR ? I know Three Bridges and Caterham aren't.

[phil-b259]

But the WR does. Are any of your examples on the WR ? I know Three Bridges and Caterham aren't.

 

The point is more about the tone of the response I received* as technically I wasn't wrong when referring to non WR designed kit

 

* I do acknowledge though I did misread Grovenor's original comment about the WR's decision to do things differently

[Grovenor]

The point is more about the tone of the response I received* as technically I wasn't wrong when referring to non WR designed kit

 

* I do acknowledge though I did misread Grovenor's original comment about the WR's decision to do things differently

You chose to contradict my message, which was correct, and relevant to the question it was answering, you should expect me to defend it.

Regards