signalling for Pant Y Rhedyn

[Happy Hippo]

Just as one signalling topic finishes, then yet another raises it's (ugly) head.

 

Due to my purchasing madness of buying an ART class 158 and now a ART 153, I really need somewhere to run them, hence Pant Y Rhedyn.

 

 

 

This is a single track junction along the lines of Blackmill junction in South Wales in the early post privatization period.From the attached illustration you can see that the original passing loop on the main line has been lifted at the down (to Cardiff) end, creating an engineering siding.

 

The goods loop is really to pass passenger and freight from the branch and to allow access to the colliery sidings.

 

Having taken as much information as I can from previous missives by the signalling fraternity, I'm confident that the signalling that I have placed on the diagram is reasonably accurate. If anything it is probably over signalled.

 

I've restricted myself to stop/go signalling with the exception of the 3 aspect signal at the down end which has two feathers to control access to both the branch and goods loop. What appears as a ground signal is (or should be) on the post and is fitted for calling on -- Either to the engineering siding, or for direct access into the colliery sidings.

 

I suspect the 2 aspect signal with the feather at up end of the branch could be three aspect .The rest of the signalling i think is pretty straight forward and I've put ground signals is to control shunting moves off the goods loop.

 

The siding off the down end of the goods loop has a trap point as it sometimes acts as a storage road for a spare loco.

 

The two ground signals controlling ex the exit from the colliery siding(s) I think should be 'yellow aspect' allowing shunting to take place within the colliery complex.

 

For what was originally a small simple junction, the signalling has started to create a bit of a monster and I could do with advice in the following area:

 

Is it grossly oversignalled?

 

Is it a workable signalling diagram?

 

Can anyone suggest any changes that would make it more realistic.

 

I have to admit that correct signalling and track work is taking over my modelling at present, and I could be running trains of tennis balls as long as the track and signalling are correct

 

Regards

 

Richard

 

Edited for technical foot in mouth!

[The Stationmaster]

Richard,

 

First off I would 'Westernize' it and ideally do that for the period when some colour light signalling appeared in that part of the world. then I would turn round the crossover into the Engineer's siding and pretend its a former riunning line trailing crossover that's been re-used and is worked by a ground frame (and that helps a few other thing like avoiding having a sub on the signal in rear of it and having it instead on a signal which will have one anyway).

 

Assuming it's a somewhat older installation I'd think very carefully about having main aspect running signals reading out of the colliery sidings - quite a number of such things went in under the early Port Talbot scheme but then the WR started saving money and leaving them out of situations like this in its later schemes. I'd make the Goods Loop to colliery connection worked by ground frame and both the GPLS reading out of the Goods Loop 'yellow light' and then do away with the two GPLs reading opposite them (the loop is only really there for the colliery if we're honest I think. No route indicator on the signal off the branch into the loop, just a sub position light with a stencil indicator but it's awfully close to the next signal in advance which means perhaps moving it off stage and just having a GPL at that point toe?

 

I can't see much point at all - unless you've got 20 feet of layout there - in having any signals to the left of the Engineer's sdg.

And now you've got a good excuse for 2 aspect signals except for the one at extreme right end which will have to be 3 aspect and you're up the Western Valley c.1971 onwards or various other spots in South wales with ageing signalling in the period that allows you running those disgusting things you mention above .

[Happy Hippo]

Mike,

 

Thank you for taking the time to look over Pant Y Rhedyn, and the suggestions you've made.

 

I waited until this morning to reply, as I wanted to fully digest and understand the points you raised and what I will now go away and redraw the diagram to incorporate (my interpretations) of your suggestions and then re post.

 

I have to admit not to have been thought of the Western Valleys as I'm more interested in a Mid to West Glamorgan scenario where there were more single lines that branched off other single lines. So a bias towards the Neath and Port Talbot area is more likely.

 

As I said in the original post I did feel it was over signalled and your remarks about the use of ground frames make sense, especially in the financial climate we operate today. Three locally operated frames (colliery in/out/engineers) is far cheaper than all the cabling back to a panel box 10 miles away.

 

I totally agree with your comment regarding the signals to the up end of the engineers siding, and equally they are relevant to the up side of the branch as well. As I drew this plan I was in two minds as to whether it should be a fiddle to fiddle or a roundy type railway. The signals had been drawn in to the extremities of the plan mainly for continuity so we could identify possible traffic routes and signal accordingly. I suspect that whichever is built, the 'on scene' section of the branch will finish at the up end of the branch platform. visually we would then lose from view the colliery access, the end of the goods loop and all the associated signalling and point work.

 

Since you have suggested changing ends with the access to the engineering siding, I'm minded to bring it further down the line and have the access to it just off the up end of the disused platform. This would shorten the scenic section of the main line quite considerably, and would make the railway more amenable to a fiddle to fiddle arrangement.

 

Another thought would be it should be a loop with a GF at each end?

 

Those that follow the Forest of Dean thread may notice that the track plan is virtually a mirror image of Serridge Junction. I was hoping for a fairly easy transposition from Gloucestershire to Mid Glamorgan. However, Mike's observations have now lead me to think of a Valleys 'main line' junction which has been heavily rationalised. This in turn would lead to the area to the up side of the main line section of the station being a large tract of rather desolate overgrown and weedy ballast representing where storage sidings and running loops once stood. A double track bridge over a river, with one side lifted at the down end had suddenly sprung to mind (Radyr Quarry to Llandaff as an example).

 

As for the name well quite simply, Pant Y Rhedyn is the road in which my parents live. the translation roughly being Fern Dip/Hollow. It was put in merely as a working title in an attempt to give it some flavour. After this it will probably change to Aberdumbboi .

 

Regards

 

Richard

 

PS For those unfamiliar with the valleys, trains are geographically orientated so an up train leaves Cardiff(in the South) for Merthyr (North), and vice versa, rather than the nationally accepted all up trains go to London.

[The Stationmaster]

Richard,

 

The only thing I would say at this stage is that I wouldn't be over keen on making the Engineer's sdg a loop - might make things a bit busy and you've already got one loop where trains can, if necessary, runround (and getting from one to the other and what happens in each will entertain far more than just going into a loop I think - but that's me).

 

Oh and nice of you to think of my old 'parish' - here in busier times

 

[Happy Hippo]

Richard,

 

The only thing I would say at this stage is that I wouldn't be over keen on making the Engineer's sdg a loop - might make things a bit busy and you've already got one loop where trains can, if necessary, runround (and getting from one to the other and what happens in each will entertain far more than just going into a loop I think - but that's me).

 

Oh and nice of you to think of my old 'parish' - here in busier times

 

Mike,

 

I have to agree with your comment about the engineer siding, especially if I bring it closer to the main branch junction.

 

Another element to factor in is that of cost! What started off as a small, cheap to build bit of fun, is rapidly turning into a serious piece of time and effort.

 

In an attempt to justify what I've done, I've very quickly drawn up a track plan (circa 1960) without semaphore signalling, and then torn out great swathes of track to let me get a feel for what would be left and why.

 

Thanks for the picture of Radyr's north End. Definitely in happier days. You'd cry if you could see what's left now.

 

Regards

 

Richard

[Happy Hippo]

The weather today was not what I wanted, so I've redrawn Pant y Rhedyn taking into account the Stationmaster's excellent advice.

 

For some reason, I decided it would be better drawn with the main line along the bottom of the drawing, so we are now looking at it upside down.

 

I rethought some of the track work, and with a bit of further rationalisation, reduced the ground frames from three to two:

 

I've also tried to draw the signals a little bit larger so they are easier to see:

 

 

The signals are:

 

1. Three aspect signal for Up main line with feathers for access to goods loop and branch. Sub for calling on to colliery sidings.

 

2. Up main start and sub to engineer siding.

 

3. Up branch start

 

4. Up goods loop start

 

5. Down main home probably should be three aspect?(but is off scene).

 

6. Down main start

 

7. Down Branch home with stencil

 

8. Down branch start

 

9. Down goods loop start and sub to head shunt

 

10. Head shunt to goods loop sub

 

X-X Ground frame to operate goods loop to colliery access/exit and operate subs

 

Y-Y Ground frame to access engineering siding and operate subs (entry co located with signal 2).

 

I've revised the goods loop and branch entries from the main: By laying them out this way it creates a longer loop.

 

Regards

 

Richard

[The Stationmaster]

 

For some reason, I decided it would be better drawn with the main line along the bottom of the drawing, so we are now looking at it upside down.

 

The signals are:

 

1. Three aspect signal for Up main line with feathers for access to goods loop and branch. Sub for calling on to colliery sidings.

This signal could also use the sub to signal a move to the engineer's sdg - and do away with the main aspect running signal No.2 but keep a GPL.

 

2. Up main start and sub to engineer siding.

As above - the main aspect could be done away with and it is awfully close to signal 1 which would be more or less at the toe of the points to the Goods Loop at that period.

 

3. Up branch start

4. Up goods loop start

Unless you are going for a sort of'Margam area 1960s' look I would do away with the running signal from the loop and substitue a GPL. If you retain the main aspect signal it should be a short range reduced aspect size version.

 

5. Down main home probably should be three aspect?(but is off scene).

Yes, but see comment regarding No.6

 

 

6. Down main start

Which brings us neatly to the question of overlaps and the fact that sited just there - without any hint of selective compression - No.6 will share its overlap with No.7 which means No.5 can't be cleared if No. 7 or No. 8 is cleared and No.8 can't be cleared towards the branch platform if No.5 or No.6 has been cleared or if a movement is signalled from the Goods Loop. The answer is obviously going to have to be some sort of selective compression - unless the layout will be a lot longer than I think it will be - and you need to think how you will apply that or if you will ignore the effect of normal overlaps, or have a very low line speed and 50 yard overlaps (which is still more than a couple of coach lengths).

 

One solution would be to not have signals No.s 6 & 8 and move No.5 closer in but on the other hand you could decide there are suitable controls in place to allow you to have No.s 6 & 8 but you won't be able to have a train approaching one of them while a train is approaching the other or you've got low line speeds (hardly unlikely of course) and you site the signals a good coach length back from the Fouling Point as a form of selective compression. I think I can guess your answer.

 

7. Down Branch home with stencil

Should have a subsidiary position light and a stencil (which I think is what you meant to say)

 

8. Down branch start

See above.

 

 

9. Down goods loop start and sub to head shunt

Could quite happily be a ground position light unless you take the 'Margam 1960s' route.

 

10. Head shunt to goods loop sub

 

X-X Ground frame to operate goods loop to colliery access/exit and operate subs

Yes although you could avoid having the GPL in the Goods Loop depending on the working you have in mind and provide a STOP board instead if there are likely to be staff on duty whenever the loop is going to be used.

 

Y-Y Ground frame to access engineering siding and operate subs (entry co located with signal 2).

See comment above re Signal No.2

 

I've revised the goods loop and branch entries from the main: By laying them out this way it creates a longer loop.

Regards

Richard

 

Good idea to alter the layout like that and making excellent progress I think plus it will all be very simple control circuitry.

[Happy Hippo]

Mike,

 

thanks for the very comprehensive critique on the revision to the PYR signalling and track diagram.

 

I have acted on most of the suggestions and have amended my drawing to suit. I haven't posted it with this message as I need to clear up a few points with you before proceeding further.

 

I appreciate how difficult it is to work on the little information that is available when someone such as myself plants a drawing on RM Web and says 'Help.'

 

In retrospect, it would have been much more help if what I consider the two main factors concerning the layout had been stated in the first post. They are:

 

a. The space I have available for the 'scenic' section of the railway, and

 

b. A fictional history and a reason for the railway operating as it does in the era modelled, and as a result of that, the level and type of traffic the line has to cope with.

 

We can easily deal with 'a' as the visible space, (although some may be curved) is a minimum of 16 feet in length.

 

The fictional history again is pretty straightforward. Located in the mid to West Glamorgan area, Pant Y Rhedyn is a junction where the river splits into the Fawr and Fach Valleys. The station sits in the V of the junction such as that at Aberbeeg. Both valleys were dotted with collieries, with one being sited close to the junction. Today it remains the only deep worked pit in the area.

 

Originally double track throughout, it was re signalled as part of the Port Talbot resignalling project in the early 1960s. In the 1980s, the main and branch were singled with the cessation of much of the coal traffic from the two valleys. The passenger service was reduced so that services beyond PYR were withdrawn.

 

By the mid 1990s, there had been a turn around in the operational requirements for the railway. Coal production at PYR remained at a high level, whilst further north open cast mining was now taking place increasing the freight flow on both main and branch. Forestry operations further north on the main line resulted in a contract for timber traffic to be ferried south by rail. The increased freight workings and the small regeneration of the area have had a knock on effect with passenger traffic, so the passenger service has now been extended back up both valleys. and the main line is now linked to Maesteg. (Please don't ask how!)

 

NR are now considering the redoubling of the route south of PYR to take into account the increased traffic levels.

 

So much for the fiction.

 

This is what I want to operate:

 

Through passenger on the main

Through passenger on the branch

Through freight on main

Through Freight on branch

Through freight on Goods loop

Stopping freight on Goods loop

 

Passenger trains held at the station on either the main or the branch whilst passenger or freight workings enter PYR from the south.

Freights held on the goods loop to allow trains to pass in the opposite direction on the branch

 

A minimum amount of shunting: the occasional train or couple of wagons shunted onto the engineers siding, and the vague impression of a colliery loco (on hire, so possibly either on 03/03 or even an 08) shuttling stuff on the colliery lines.

 

 

As you can gather the main line is fairly straightforward: Trains up and trains down some working straight through whilst others waiting whilst the line south is occupied by a train wanting to access the branch.

 

The same is true of the branch, with the goods loop being used to pass either freight or freight and passenger.

 

These account for why I've placed the signals at the platform ends and at the ends of the goods loop Margam style!

 

Thank you for the observation of the overlaps required. I presumed that all southbound trains would need to be signalled prior to the junction, and assumed that the platform ends would be the appropriate place to site the signals. Because of the space I have available (or will make available), the distance between the end of the platform and the junction is going to be around 18-24". This is one of the problems when you draw a diagram that is not to scale.

 

Likewise the goods loop and branch would be parallel to each other for around 12 feet, and may possibly even disappear into the fiddle yard without joining up 'on scene'.

should that be the case then the signals at locations 3,4 and 7 would not appear the scenic section.

 

Perhaps under the circumstances I ought to consider a banner repeater at the up end of the branch platform which would allow the train (passenger) to sit at the platform until given the line clear signal?

 

What all this does prove to me is that although the basic principles of railway signalling remain the same, transferring from mechanical to colour light does raise a number of interesting issues to resolve.

 

Regards

 

Richard

[The Stationmaster]

 

These account for why I've placed the signals at the platform ends and at the ends of the goods loop Margam style!

 

Thank you for the observation of the overlaps required. I presumed that all southbound trains would need to be signalled prior to the junction, and assumed that the platform ends would be the appropriate place to site the signals. Because of the space I have available (or will make available), the distance between the end of the platform and the junction is going to be around 18-24". This is one of the problems when you draw a diagram that is not to scale.

Richard I think (and this a very personal view of course) that in 4mm scale a distance of 24" represents a very reasonable figure for a selectively compressed overlap - that's a sort of expansion of my view that a quarter mile Absolute Block Clearing Point could reasonably be selectively compressed to a long train length plus a coach ('a long train length' of course varying with layout size to some extent but also not being such a short train as to look stupid). So to return to your junction in the valleys you are going to have a reasonable 'lower speed' overlap - excellent and it will look credible with the signals set back in rear of the junction.

 

Likewise the goods loop and branch would be parallel to each other for around 12 feet, and may possibly even disappear into the fiddle yard without joining up 'on scene'.

should that be the case then the signals at locations 3,4 and 7 would not appear the scenic section.

Which would look even better because the distance will be as much as the casual viewer thinks it ought to be.

 

Perhaps under the circumstances I ought to consider a banner repeater at the up end of the branch platform which would allow the train (passenger) to sit at the platform until given the line clear signal?

I would say not - there is (back then) no operational justification for it unless you consider the signal it applies to to be immediately off-scene and obscure by a bridge or whatever. Equally if you fancy the challenge and want to provide one then you are saying something about the line ahead which you might consider useful. In other words whatever you do will be 'right'.

 

What all this does prove to me is that although the basic principles of railway signalling remain the same, transferring from mechanical to colour light does raise a number of interesting issues to resolve.

Regards

Richard

Yes and even more interesting is how to apply them to a model railway because although principles are a given (qualified by time and place and relevant Regional practice) some aspects (sorry, couldn't think of another word) of colour light signalling such as overlaps do not sit too easily with the space constraints of most model railways and this is where we have to think seriously about how we apply selective compression.

[Happy Hippo]

Mike,

 

I've now redrawn the plan to show the on and off scene sections of the track and signalling diagram for PYR:

 

 

 

 

The only visible main aspect signal in the up direction is the junction signal.

This remains 3 aspect with 2 feathers and a sub for calling on to either of the ground frames.

 

I've removed the main aspect signals both up and down on the goods loop and replaced them with ground signals.

I'm showing a pair at the down end of the loop, one for the loop to main and the other loop to head shunt.

 

I've removed the colliery access sub and replaced it with a stop board.

 

I've taken your advice and not bothered with the banner repeater at the up end of the platform branch.

 

The only two visible main aspect signals in the down direction are at the down main and down branch platform ends.

 

Well off scene are a couple of three aspect signals for the down main and the branch. The latter also being fitted with a sub and a stencil.

 

I think that covers all the points you've raised for me.

 

One observation I've had about this thread is the lack of questions or any other input from other RM Webbers. Most unusual!

 

Regards

 

Richard

[The Stationmaster]

 

The only visible main aspect signal in the up direction is the junction signal.

This remains 3 aspect with 2 feathers and a sub for calling on to either of the ground frames.

 

I've removed the main aspect signals both up and down on the goods loop and replaced them with ground signals.

I'm showing a pair at the down end of the loop, one for the loop to main and the other loop to head shunt.

 

I've removed the colliery access sub and replaced it with a stop board.

I've taken your advice and not bothered with the banner repeater at the up end of the platform branch.

The only two visible main aspect signals in the down direction are at the down main and down branch platform ends.

Well off scene are a couple of three aspect signals for the down main and the branch. The latter also being fitted with a sub and a stencil.

I think that covers all the points you've raised for me.

One observation I've had about this thread is the lack of questions or any other input from other RM Webbers. Most unusual!

 

Regards

Richard

Taking the last first I think we tend to recognise each other's areas of particular expertise/Regional etc knowledge and several of us don't bother to join in for the sake of it while one seems to be coping (usually).

Only one other point at this stage Richard and that is the exit from the Goods Loop/towards the headshunt where you have got a bit 'semaphore-ish and put in two GPL heads - something I don't think the Western ever did (although it did happen on one Region/Company in some earlier schemes judging by what i saw many years ago. All you need is a single GPL, and no route indicator associated with it for the period you have in mind.

 

All in all a very nice track layout I think that should look good and create the right atmosphere of time & place. Next stage will be to get signal details, colours etc sorted for you as you really must get the correct 'Western' appearance

[Happy Hippo]

Mike,

 

Thank you for all your help on this project it is much appreciated.

 

I know how long writing replies can take, and of course there is the impact on your own modelling and any other interests you have.

 

I have amended the diagram, to reflect your observation about the down loop exit and I now only have the one GPL there. I haven't bothered to repost the drawing for such a small change.

 

As a modeller whose main interest lie firmly in the steam age, I suspect this is where my 'semaphore-ish' tendencies originate.

 

However, I place the blame for this quantum leap squarely on the heads of all those modellers on RM Web whom have been peddling gently, the concept of a modern image model railway at me.

 

It's obviously rubbing off.

 

I can now draw up the plan to scale, and start to get the boards built and profiled, although I cannot see much movement on that front until about Christmas time.

 

Ideally I'd like to put in 'proper' hand laid track, but realistically this is supposed to be a railway I can build in a reasonably short time frame, so I suspect Peco code 75 and large radius points straight from box to board will be the way forward.

 

In closing, I have to admit that a lot of the pleasure I'm getting from this project is stretching my brain and learning new aspects about railways that previously I was ignorant of. I've still got quite a bit of research to do, but I'm enjoying the challenge.

 

Regards

 

Richard