Simple Signalling/Section Question - Single Track Line

[KingEdwardII]

1 hour ago, Ian J. said:

Here's a diagram I drew up yesterday for Cold Holt

Since you've indicated that this is a preservation era station and you are clearly signalling to allow for running both ways through both platforms (probably not so common on pre-preservation lines), then I'll draw attention to the way that Toddington station is signalled on the GWSR, which in similar to Cold Holt in some respects.

 

Here are pictures of the south end of Toddington:

 

and the north end of Toddington:

 

In both cases, there are starter signals for each platform, as you have for Cold Holt, but positioned somewhat off the ends of the platforms. However, the home signals are junction bracket signals - one arm for each platform.

 

On the south end you will also note some signals beyond the starter signals - I think that there is at least one advanced starter - I have not been able to find a better picture of these signals. Note that the south side of Toddington has an extensive yard both for storage and for the sheds where restoration work takes place and there are connections to/from the yard on the line south.

 

There are also subsidiary arms on the junction bracket on the south side used to control shunting movements, etc.

 

Yours,  Mike.

 

PS You can get an idea of the actual positioning of the signals at Toddington using Google Maps satellite view - the view was taken in the afternoon so that the signals throw very recognisable shadows enabling you to work out which is which. This also gives a clear view of the yard at Toddington and the connection from the yard to the main line.

Edited August 30, 2021 by KingEdwardII

[The Stationmaster]

1 hour ago, Ian J. said:

I investigated further how to create objects in AnyRail and I've been able to cobble together a Home and Distant and white/red and black/yellow discs. I've kept the original drawn items in ungrouped form in a separate file so I will be able to reuse them to put together variations. It's a bit fiddly to use for object drawing, but I worked out how to get round a problem or two and the objects look OK.

 

So, onto my next question: what are the 'rules' for where ground signals go? The only one I've ascertained so far is the black/yellow for exits to a 'main' line where there is another viable route between the signal and the 'main' line exit, meaning the black/yellow can be passed at 'on'.

 

Here's a diagram I drew up yesterday for Cold Holt, the first station on the S&P, without any ground signals:

 

 A good start.  Presumably both platforms will be bi-directional in which case you would need splitting Home Signals so that a train can run to either platform.

 

What we then need to look at is the need for trap points from the sidings (they can be made as dummies) and there would be a red arm ground disc at each of them.  There would also need to be a ground disc in the running lines, adjacent to the semaphore stop signals to read to each lot of sidings.

 

The next thing to consider is running an engine round a train.  If that is going to happen the heritage lines tend to go in for subsidiary Calling On signals although technically they are not essential.

 

The only other thing I woud suggest is a ground disc at teh toe of the point where the platform loops diverge at the turntable end of the station - that would help when shunting and would enable you to avoid Calling On subsidiaries on the Home Signal at that end asa an engine running round need go no further than that signal.

[St Enodoc]

 

27 minutes ago, KingEdwardII said:

Since you've indicated that this is a preservation era station and you are clearly signalling to allow for running both ways through both platforms (probably not so common on pre-preservation lines), then I'll draw attention to the way that Toddington station is signalled on the GWSR, which in similar to Cold Holt in some respects.

 

Here are pictures of the south end of Toddington:

 

and the north end of Toddington:

 

In both cases, there are starter signals for each platform, as you have for Cold Holt, but positioned somewhat off the ends of the platforms. However, the home signals are junction bracket signals - one arm for each platform.

 

On the south end you will also note some signals beyond the starter signals - I think that there is at least one advanced starter - I have not been able to find a better picture of these signals. Note that the south side of Toddington has an extensive yard both for storage and for the sheds where restoration work takes place and there are connections to/from the yard on the line south.

 

There are also subsidiary arms on the junction bracket on the south side used to control shunting movements, etc.

 

Yours,  Mike.

 

PS You can get an idea of the actual positioning of the signals at Toddington using Google Maps satellite view - the view was taken in the afternoon so that the signals throw very recognisable shadows enabling you to work out which is which. This also gives a clear view of the yard at Toddington and the connection from the yard to the main line.

If you want to use Toddington as your template, you can do no better than look here:

 

https://www.roscalen.com/signals/GWSR/Toddington/index.htm

Edited August 30, 2021 by St Enodoc
Quoted post appeared twice

[KingEdwardII]

13 minutes ago, St Enodoc said:

you can do no better than look here:

Just be aware that some of those pictures appear to be of a vintage before the line north to Broadway from Toddington was reinstated. The north end has changed a bit since then - there are some pictures of the more recent arrangements towards the bottom of the page.

 

Yours,  Mike.

Edited August 30, 2021 by KingEdwardII

[St Enodoc]

Just now, KingEdwardII said:

Just be aware that those pictures appear to be of a vintage before the line north to Broadway from Toddington was reinstated. The north end has changed a bit since then.

 

Yours,  Mike.

Scroll  down and you will see some commentary on those changes. It doesn't cover the full extension to Broadway but does cover the interim terminus at Lavington.

[KingEdwardII]

8 minutes ago, St Enodoc said:

It doesn't cover the full extension to Broadway

Indeed, the full story of the Broadway extension is not finished even today. They are still working on the signal box at Broadway and many of the Broadway signals are not yet in use.

 

(Re)building a heritage railway is a slow and steady business, limited by availability both of funds and of volunteers to do the work.

 

I think that Broadway station is an astounding piece of work - they started with nothing, since all of the original station had been obliterated. The full saga is told in the blog pages here:

 

https://broadwaystationgroup.blogspot.com/

 

And today they have a wonderfully atmospheric re-creation of the Edwardian station. Still not complete - the work on the footbridge continues, platform 2 needs a shelter building and proper surfacing, the signal box needs commissioning. 

 

Yours,  Mike.

[Michael Hodgson]

1 hour ago, KingEdwardII said:

Since you've indicated that this is a preservation era station and you are clearly signalling to allow for running both ways through both platforms (probably not so common on pre-preservation lines)

 

 

... except in Ireland, where many if not most stations were signalled bi-directionally.  Ireland closely followed British practice (because when semaphore signalling started, it was British of course).  There was good reason for this.  On a long single track main line it is quite common for a passenger train not to be crossing a goods or not to pass another train at all, and it is more convenient for the passengers if the passenger train uses the platform adjacent to the main building and they don't have to use the footbridge.   

[Ian J.]

Thanks all for the replies. I'm a bit busy so otherwise occupied today, but I'll revisit the Cold Holt plan tomorrow evening and see if I can add ground signals in suitable places, alter the Homes to two on a gantry on a post, and see if I can illustrate calling on arms.

[Ian J.]

Cold Holt v1.1, with split homes, ground signals, trap points (thought they are barely visible), and subsidiaries:

 

 

I think I've read @The Stationmaster's feedback correctly.

 

Edit: apologies for the image quality, it seems RMweb is doing a large amount of compression to the image, which for this basic drawing isn't really required.

Edited August 31, 2021 by Ian J.
Change picture format

[GrahamH]

In connection with the provision (or otherwise) of outer home and advanced starting signals at single line crossing places on heritage railways, probably it is worth considering the interlocking practices at some locations. For example, at some heritage installations (Toddington and Ropley I am aware of, though almost certainly there are others), the interlocking of the home signal protecting the main/loop points also requires the exit points at the opposite end to be set for the single line. I presume that this is to protect the points from being run through if a train fails to stop at the starting signal, though I do not know this for a fact. The consequence is, of course, that the simultaneous acceptance of crossing trains would not be possible as the facing points would not then be set correctly for the opposing train to run on its line to the starting signal. The consequence then is that outer homes have to be provided for acceptance purposes, and usually advanced starting signals are also provided. The clearing point is then defined as running from the outer home signal to the advanced starting signal for the opposite direction. A forest of signals, and plenty of levers for the signalman to operate!

[Nick C]

50 minutes ago, GrahamH said:

In connection with the provision (or otherwise) of outer home and advanced starting signals at single line crossing places on heritage railways, probably it is worth considering the interlocking practices at some locations. For example, at some heritage installations (Toddington and Ropley I am aware of, though almost certainly there are others), the interlocking of the home signal protecting the main/loop points also requires the exit points at the opposite end to be set for the single line. I presume that this is to protect the points from being run through if a train fails to stop at the starting signal, though I do not know this for a fact. The consequence is, of course, that the simultaneous acceptance of crossing trains would not be possible as the facing points would not then be set correctly for the opposing train to run on its line to the starting signal. The consequence then is that outer homes have to be provided for acceptance purposes, and usually advanced starting signals are also provided. The clearing point is then defined as running from the outer home signal to the advanced starting signal for the opposite direction. A forest of signals, and plenty of levers for the signalman to operate!

 

From what I understand, this largely depends on when they were resignalled - the concept of having both ends of the loop in correspondence is a more recent ORR requirement, as you say to prevent run-through in the event of a SPAD - but obviously isn't possible without an outer home as you'd then not have a clearing point.

[GrahamH]

2 minutes ago, Nick C said:

 

From what I understand, this largely depends on when they were resignalled - the concept of having both ends of the loop in correspondence is a more recent ORR requirement, as you say to prevent run-through in the event of a SPAD - but obviously isn't possible without an outer home as you'd then not have a clearing point.

That's interesting. I'd not realised that it was a requirement from the ORR. There's nothing specific in the old  ORR Guidance for Minor Railways in the interlocking requirements section (paragraphs 312 - 228). Is there anything more specific elsewhere, so far as you are aware, or was it a "local" interpretation given at the time that the railways employing this particular interlocking were signalled, maybe at the request of a particular inspector who had a "thing" about it?

[Nick C]

I'm not sure whether it was an official thing, or just a guidance/recommendation - just an impression I got from chatting to some of the S&T types at Ropley was that it was the preferred way of doing it. Alresford is the same, though obviously not a passing place, but both ends of the loop have to be set the same for any incoming move.

 

Edit - it might have been an RSSB thing rather than ORR - I've not got access to their interlocking principles documents though

Edited September 1, 2021 by Nick C

[The Stationmaster]

2 hours ago, GrahamH said:

In connection with the provision (or otherwise) of outer home and advanced starting signals at single line crossing places on heritage railways, probably it is worth considering the interlocking practices at some locations. For example, at some heritage installations (Toddington and Ropley I am aware of, though almost certainly there are others), the interlocking of the home signal protecting the main/loop points also requires the exit points at the opposite end to be set for the single line. I presume that this is to protect the points from being run through if a train fails to stop at the starting signal, though I do not know this for a fact. The consequence is, of course, that the simultaneous acceptance of crossing trains would not be possible as the facing points would not then be set correctly for the opposing train to run on its line to the starting signal. The consequence then is that outer homes have to be provided for acceptance purposes, and usually advanced starting signals are also provided. The clearing point is then defined as running from the outer home signal to the advanced starting signal for the opposite direction. A forest of signals, and plenty of levers for the signalman to operate!

Which as an arrangement directly facilitates the potential for a head-on collisions.  Running through trailing points, if they are not bolted by an FPL,  is unlikely to do no more than damage than to the switches and point rodding.  If however the exit points are set for a train arriving at the other end it goes exactly against the lessons of history (which are prob ably what led to the past instructions for crossing loops).

 

Surely if a train is halted before it is allowed to pass the Home Signal not only would it be less likely to pass the Starting Signal at danger than it would have been it had only been checked at the Home Signal and that signal had been cleared before the train came to a stand?  It looks almost as if someone is trying to create what amounts to a full Clearing Point where there isn't really one and has finished up with an unintended consequence as a result - if Driver is going to run through a signal ata. crossing loop of all places there's no guarantee that he/she will bring their train to a stand in the next 440 yds.  Looks like somebody didn't properly think out their risk assessment (if they did one at all?).

[Nick C]

14 minutes ago, The Stationmaster said:

Which as an arrangement directly facilitates the potential for a head-on collisions.  Running through trailing points, if they are not bolted by an FPL,  is unlikely to do no more than damage than to the switches and point rodding.  If however the exit points are set for a train arriving at the other end it goes exactly against the lessons of history (which are prob ably what led to the past instructions for crossing loops).

 

Surely if a train is halted before it is allowed to pass the Home Signal not only would it be less likely to pass the Starting Signal at danger than it would have been it had only been checked at the Home Signal and that signal had been cleared before the train came to a stand?  It looks almost as if someone is trying to create what amounts to a full Clearing Point where there isn't really one and has finished up with an unintended consequence as a result - if Driver is going to run through a signal ata. crossing loop of all places there's no guarantee that he/she will bring their train to a stand in the next 440 yds.  Looks like somebody didn't properly think out their risk assessment (if they did one at all?).

I don't get how the position of the exit points makes a difference to the likelyhood of a train passing the starter at danger? Would running through the points do anything much to retard the progress of the train?

 

Plus if the arriving train did SPAD the starter, the opposing train is some 900-odd yards away, sitting at the outer home, rather than <200 yards away at the inner home...

[The Stationmaster]

9 minutes ago, Nick C said:

I don't get how the position of the exit points makes a difference to the likelyhood of a train passing the starter at danger? Would running through the points do anything much to retard the progress of the train?

 

Plus if the arriving train did SPAD the starter, the opposing train is some 900-odd yards away, sitting at the outer home, rather than <200 yards away at the inner home...

First of all the arriving train would be no more than 440yds away if outermost Home Signal is solely provided for acceptance purposes.    As far as running through unbolted points is concerned I doubt it would do much to retard a train although it would probably damage the rodding.  

 

Back in 1978 in the heavy snow one of my Signalmen ran an empty HST through the trailing end of a crossover and it didn't do any damage to anything.  I have seen 'box worked trailing points run through where you would have to do a lot of looking to find the damage to the rodding.  And sometimes all that happened was the channel rodding run would be moved or lifted, without even noticeably buckling (some way away) from the points especially if the stools weren't properly buried or were in a spot of soft ground.

[KingEdwardII]

3 hours ago, GrahamH said:

to protect the points from being run through if a train fails to stop

The GWSR learned to their cost the effects of this happening, at Broadway where things are still not finalized, as I explained earlier.

 

King Edward II, no less, ran through the turnout at the south end of Broadway station while running around a train, with the turnout set against it. As you can envisage, a massive loco like KE II did a proper job on the metalwork of the turnout, which had to be removed for major repairs, preventing run-rounds. The operating procedures for Broadway trains had to be altered for the duration, with "topping and tailing" (ie loco on each end of a train) required to enable trains to run in and out of Broadway.

 

Yours, Mike.

[DCB]

17 hours ago, Ian J. said:

Cold Holt v1.1, with split homes, ground signals, trap points (thought they are barely visible), and subsidiaries:

 

 

I think I've read @The Stationmaster's feedback correctly.

 

Edit: apologies for the image quality, it seems RMweb is doing a large amount of compression to the image, which for this basic drawing isn't really required.

Is this set up for right hand running?   It looks like a mirror image of normal UK practice.

[Ian J.]

21 minutes ago, DCB said:

Is this set up for right hand running?   It looks like a mirror image of normal UK practice.

 

Nope. It's an arrangement where trains from Bere Dene terminate in Platform 2, and trains from Sayersbridge terminate in Platform 1. This is due to uncertified heritage stock not being allowed on the Network main line (the route plan as per posted on the S&P blog):

 

 

And before anyone asks, this isn't actual real geography, I've 'altered' it such that it's now an 'alternate universe' geography to suite my needs rather than try and find one location that would suit my needs. It is however heavily influenced by Dorset and Wessex, and only applies to the local geography such that other places still exist as normal (Exeter, Bristol, Bath, London, etc).

[Nick C]

1 hour ago, The Stationmaster said:

First of all the arriving train would be no more than 440yds away if outermost Home Signal is solely provided for acceptance purposes. 

However in the examples quoted it's generally not just for acceptance purposes, but also to enable more flexible working - at Ropley there is several coach-lengths between inner home and advanced starter, to allow most shunting without having to get a token, plus the clearance distance from there to the outer home. Toddington appears to be the same - measuring on Google maps gives 770m in a straigth line from the end of the platform to the outer home.

[Ian J.]

Regarding operation of stations, in model form I'm planning that all signalling, points, etc will be controlled from a central computer, and therefore all interlocking will be controlled by that software rather than with physical or electrical interlocking on the model.

[Ian J.]

Re having to occupy a block section as for Cold Holt, there might be a need for 'off stage' outer home and advanced starter signals at the Sayersbridge end of the station, as the running round would otherwise necessitate occupying a block section shared with the national Network, something that probably would want to be avoided so as not to annoy the national Network signalman...?

[Michael Hodgson]

54 minutes ago, Ian J. said:

 

Nope. It's an arrangement where trains from Bere Dene terminate in Platform 2, and trains from Sayersbridge terminate in Platform 1. This is due to uncertified heritage stock not being allowed on the Network main line (the route plan as per posted on the S&P blog):

 

That sounds to me like right hand running but without through running.  If trains in both directions only ever terminate in their respective platforms, the signals for them to continue out of the loops would presumably be fixed at Danger, like the one at the north end of Boat of Garten on the Strathspey line before it extended to Broomhill?

[Michael Hodgson]

1 hour ago, Ian J. said:

Re having to occupy a block section as for Cold Holt, there might be a need for 'off stage' outer home and advanced starter signals at the Sayersbridge end of the station, as the running round would otherwise necessitate occupying a block section shared with the national Network, something that probably would want to be avoided so as not to annoy the national Network signalman...?

Wouldn't the National Network require a trap under their control, probably off-stage at the junction and with its own signal?

[Ian J.]

1 hour ago, Michael Hodgson said:

 

That sounds to me like right hand running but without through running.  If trains in both directions only ever terminate in their respective platforms, the signals for them to continue out of the loops would presumably be fixed at Danger, like the one at the north end of Boat of Garten on the Strathspey line before it extended to Broomhill?

 

Is right hand running into the platforms on a single track line a no-no then...? I have no idea as I'm not sufficiently knowledgeable about such things. When I was laying out the plan, I was thinking about left hand when terminating trains depart, not when they arrive.

 

1 hour ago, Michael Hodgson said:

Wouldn't the National Network require a trap under their control, probably off-stage at the junction and with its own signal?

 

Again, I'm not the expert so I have no idea what the arrangements between a heritage line and the national network are and would need guidance on that.

Edited September 1, 2021 by Ian J.