Ground signals and signalling diagrams

[ChooChoo_Baloo]

I am trying to gain a good understanding of prototypical Great Western signalling before embarking on my model railway. I plan to have working signals installed.

 

Ground signals (the late GWR full white disc with red bar design) have been a source of confusion though, and I would appreciate it if people could please explain the 'rules' thoroughly to me:

 

 

 

 

At stations was the reason for having ground signals simpy to indicate to the engine driver which way the adjacent set of facing points were set?

 

If so, then do ground signals always occur in minimum stacks of two - the top disc referring to the left route, the bottom to the right.

 

However I am aware the ground signals did often exist individually next to a set points. In order to be able to indicate which route the blades are set to, I presume there was a convention for which route the single ground signal always referred to? This leads me on to signalling diagrams. Please see an example one below:

 

 

 

I have noticed that points are always drawn as continuous line with a non touching curvy route to the side. Am I right in assumung that the convention was that the ground signal always referred to the straight ahead route? Hence is this why singalling diagrams always showed the striaght ahead route as the continuous line? Taking ground signal 9 for example, signal horizontal bar = straight ahead "on" = points set to curving route/ onto the up line?

 

How did the driver interpret these signal ground signals? I assume they also followed the same covention as the signalling diagram - that the signal ALWAYS referred to the straight ahead route?

 

Finally - ground signal stacks. Were these used to indicate settings for each successive point on a 'fan' of sidings? I presume it was simply neater than placing one next to each point?

 

Many thanks in advance.

[Kris]

Ground signals were used to signal routes, in the case of your diagram they are being used to signal routes into sidings and / or reverse line running. They work in the same way "normal" signals and must be obeyed, they are not directly used to indicate point blade direction. Discs were/are normally found on there own.

 

Points are drawn in the direction that they would normally be set, so in the case of the drawing all points are normally set for travel along the main line. This is a standard convention and means that they only need changing for trains that need to shunt where as the majority of trains will go straight through.

[jamie92208]

I'll try and help but am by no way an expert.

1. On signal diagrams like this the points are usually drawn in the 'normal' position where the lever is back in the frame. When the lever is pulled over the 'reverse' route is set. This means that when all point levers are back in teh frame the layout is usually set for through running on the main lines.

 

2. Ground signals were used for a variety of reasons.

 

a) On the main lines to show a route that was away from the main line, often in the opposite direction to the normal direction of travel. This shows on the left ahnd side of the diagram where there is a ground signal allowinjg trains to reverse from the main line into the up siding.

 

B) They also allowed movement out of sidings and goods lines onto passenger lines. In the same example as above from the up siding onto the up main. This would allow movement up to the next standard signal.

 

c) Where there were several possible routes, eg into a fan of sidings then there would be a stack of several ground signals one above the other. The driver's route knowledge would mean that he knew which one to follow.

 

I'm sure that the railwaymen on the forum will be able to give you better information but hope that this helps.

 

Jamie.

[RELIEF SIGNALMAN]

I am trying to gain a good understanding of prototypical Great Western signalling before embarking on my model railway. I plan to have working signals installed.

 

Ground signals (the late GWR full white disc with red bar design) have been a source of confusion though, and I would appreciate it if people could please explain the 'rules' thoroughly to me:

 

 

 

 

At stations was the reason for having ground signals simpy to indicate to the engine driver which way the adjacent set of facing points were set?

 

If so, then do ground signals always occur in minimum stacks of two - the top disc referring to the left route, the bottom to the right.

 

However I am aware the ground signals did often exist individually next to a set points. In order to be able to indicate which route the blades are set to, I presume there was a convention for which route the single ground signal always referred to? This leads me on to signalling diagrams. Please see an example one below:

 

 

 

I have noticed that points are always drawn as continuous line with a non touching curvy route to the side. Am I right in assumung that the convention was that the ground signal always referred to the straight ahead route? Hence is this why singalling diagrams always showed the striaght ahead route as the continuous line? Taking ground signal 9 for example, signal horizontal bar = straight ahead "on" = points set to curving route/ onto the up line?

 

How did the driver interpret these signal ground signals? I assume they also followed the same covention as the signalling diagram - that the signal ALWAYS referred to the straight ahead route?

 

Finally - ground signal stacks. Were these used to indicate settings for each successive point on a 'fan' of sidings? I presume it was simply neater than placing one next to each point?

 

Many thanks in advance.

 

 

There are 2 types of disc signals : the most common being the horizontal red stripe which when horizontal is classified as a signal to stop, when cleared the disc will turn diagonally (45 degrees) which in the case of signal 9 in the diagram would indicate that the points would be set for the up main.

 

The other example is a "yellow" disc ; works the same way as a red stripe example but say for instance that you had sidings ahead (on the sidings pass the signal)a train can pass signal 9 at danger ; the signal is normally cleared for any movements to the up main only.

[beast66606]

The other example is a "yellow" disc ; works the same way as a red stripe example but say for instance that you had sidings ahead (on the sidings pass the signal)a train can pass signal 9 at danger ; the signal is normally cleared for any movements to the up main only.

 

Specifically it can be passed for routes to which it does not apply, this is not always to the main line although it's the most frequent use.

 

Ground signals are signals provided for low speed shunt moves, simples

[PaulRhB]

The difference between a main signal and a ground signal is this,

Main Signal

The line is clear as far as the next main signal.

 

Ground signal

The line is only clear as far as you can see so proceed at a speed that allows you to stop short of any obstruction, hence Beasts comment about low speed moves only. The obstruction can be the buffers in a siding or other stock. So they can be used for a loco running round a passenger train as there aren't passengers on the moving part.

Ground signals are not used for passenger train moves under normal working as a result. If a passenger train needs to enter an occupied line then there will be a calling on signal provided beneath a main signal.

 

(Modern signalling rules do allow certain moves to be made by passenger trains on the authority of a ground signal but only if allowed at that location and the driver and Signalman come to a clear understanding first and there is a guard on board too.)

[The Stationmaster]

As you have asked about GW practice I will stick wholly to that as it's a bit different from the doings of lesser Companies - and fortunately you have chosen a diagram which illustrates one of its principal peculiarities (which no one else) has picked up. So, first, to summarise a few things already explained -

 

1. On signalling diagrams points are drawn showing their normal lie - what this means is that the line through the points which is drawn as a continuous line is the route for which the points are normally set. When the signalbox lever which works those points is pulled over to its reverse position the points are moved to their reverse position and the route through them is set towards the line which is not drawn as continuous on the diagram.

 

2. Ground signals are normally used to control shunting movements - in modern terms when they are cleared they only indicate to a Driver that the route is set but that the line ahead might be obstructed by, say, another vehicle and that he must keep a good lookout ready to stop at any time after passing the signal.

 

3. The GWR did not use ground signals with a yellow arm (the proper way of describing one which has a yellow line on the face of the disc) so you can ignore that explanation for the GWR period and get it completely out of your mind to avoid confusion with what comes next

 

4. If you look very carefully at the diagram of Wilmcote you will see that certain ground signals have the letter 'w' next to them (7, 12, and 17) - this letter indicates that they show a white light (instead of a red light) when they are standing at danger/'on'. This was a peculiarity of GWR practice (which continued well into BR days on former GWR lines) and what you could find where ere is a succession of such signals is that they might have white lights but always the final one on that line in the wrong direction (e.g 14 and 18 at Wilmcote) will have a red light - it acts as an absolute stop signal when it is in the 'on' position and thus has a slightly different meaning from the white light signal. A Driver could pass a white light ground signal in the 'on' position provided that he received an instruction to do so from the Signalman or a Shunter; the red light version could not be passed in the 'on' position but only when it was 'off'.

 

The way the white light signals were used becomes a bit clearer if you again look at the diagram - No.17 would be cleared for a movement to the Down Refuge Siding (and then show a green light) but would not be cleared for a movement towards No.14 ground signal; No.7 would be cleared for a movement towards the Up Sidings but would not be cleared for a movement towards No.12. No.14 is an oddity because it is the final signal that would be approached in the wrong direction it has a red light and could only be cleared when crossover 13 is in reverse but it also would read to the Up Sidings (this might actually be slightly different in practice but I can't tell without the locking chart and you can ignore that bit of finesse for practical purposes).

 

5. The GWR did use multiple arm discs at some places and practice varied over the years - best to look at dated photos but small stations were most likely to have single arm discs except for some moves. You need to study locations carefully to get a feel of the way they did the job.

6. The reason for using white light signals was almost certainly to avoid the need to pass signals at danger and discs were converted from red to white light on a campaign basis in the 1890s. The reason for this was that some of the older GWR designs of interlocking did not readily allow a lever working points to release a signal lever while in either position - the release could only come if the point lever in the signalbox was at normal or reverse. So the GWR answer was to introduce white light ground discs (and Backing Signals also used white lights when in the 'on' position).

 

7. Where multiple stacks of ground discs were used the normal convention of top (arm) to bottom (arm) reading from extreme left hand (route) to extreme right hand (route) applied.

 

Hope that helps a bit.

[buffalo]

Somewhat OT as it doesn't concern the ground signals, but could I add a couple of questions about the Wilmcote diagram?

 

1 and 24 refer to one arm only. Does this mean that the other arm was controlled by the next box?

 

On signals 3 and 24 there is a squiggle on the post. Is this an 'S' indicating that they were slotted with the next box?

 

Are 5 and 6 detonator placers?

 

Nick

[Fay Singpoint]

1 and 24 refer to one arm only. Does this mean that the other arm was controlled by the next box?

 

That's correct. No 1 is the Down Distant which would be slotted by the section signal at Bearley West Junction No24 is Wilmcote's section signal which slots Bearley West Junctions Up Distant

 

 

On signals 3 and 24 there is a squiggle on the post. Is this an 'S' indicating that they were slotted with the next box?

The squiggle is the letter "B" denoting that the signal requires a line clear release on the block instrument

 

Are 5 and 6 detonator placers?

Yes

[buffalo]

Thanks, Fay. Two out of three shows I must be learning something from you signalling gurus

 

And now, a supplementary question. What is the thing that lools like a trap/catch point with an 'S' next to signal 1?

 

Nick

[The Stationmaster]

Thanks, Fay. Two out of three shows I must be learning something from you signalling gurus

 

And now, a supplementary question. What is the thing that lools like a trap/catch point with an 'S' next to signal 1?

 

Nick

 

That's a 'spring point' (in this particular case a 'catch point'). A bit on drawing conventions might be helpful here in relation to your question about signals 1 & 24 where you will note that the arms worked by this 'box are drawn 'open' while those worked by another 'box are blocked-in - this is a standard drawing convention on diagrams of this sort as are all the other methods of presentation except the way the signalposts are drawn.

Incidentally I do hope the OP obtained permission before posting this extremely useful diagram. I would not like to see it taken down because it has been so very useful in explaining things but I know that John Hinson guards the copyright of his material with some vigour and takes very great exception to misuse of it. While I'm sure he would be quite happy seeing it used in the way it has been in this thread I do hope it's here with his permission, no doubt the OP can confirm that is the case.

 

It can be linked http://www.signalbox.org/diagrams.php?id=350 should it happen to vanish from its spot above

[Andy Y]

Incidentally I do hope the OP obtained permission before posting this extremely useful diagram. I would not like to see it taken down because it has been so very useful in explaining things but I know that John Hinson guards the copyright of his material with some vigour and takes very great exception to misuse of it. While I'm sure he would be quite happy seeing it used in the way it has been in this thread I do hope it's here with his permission, no doubt the OP can confirm that is the case.

It can be linked http://www.signalbox...rams.php?id=350 should it happen to vanish from its spot above

 

Many thanks; I've removed the image from the server and replaced it with the link given to conform to copyright rules whilst clarification is sought.

 

 

 

[ChooChoo_Baloo]

Thanks to all the members who left useful advice.

 

With regards to copyright of the Wilmcote signalling diagram, I was not aware of any stringent protection of these excellent diagrams. In short: I did not make any enquiries to the author. I simply provided it as a good reference (as a jpeg upload job), in order to make explaining the topic easier. I would have thought that for purely 'academic' discussion such as this, provision of such diagrams is harmless?

 

Please can an administrator clarify the issue for me.

[beast66606]

Thanks to all the members who left useful advice.

 

With regards to copyright of the Wilmcote signalling diagram, I was not aware of any stringent protection of these excellent diagrams. In short: I did not make any enquiries to the author. I simply provided it as a good reference (as a jpeg upload job), in order to make explaining the topic easier. I would have thought that for purely 'academic' discussion such as this, provision of such diagrams is harmless?

 

Please can an administrator clarify the issue for me.

 

It's quite simple, if you don't own it you have no automatic right of use, check first (it's also good manners) "a good reference" will not protect you in court

 

See here

[Mod5]

Thanks to Beast for his simple clarification. Without going into all of the arguments about Copyright yet again it really is as simple as that as far as the forum is concerned. There is a thread here which you can read by all means as it is part of the Forum Rules but Beast has actually cut to the chase fairly well.

[Tim V]

That's the first ex WR diagram I've seen that has information about the lights. The rest of it is pretty standard.

[Tim V]

Here is a digram from a box which illustrates some of the aspects (!) Original was in the Didcot museum. Not signed by the usual AK.

[The Stationmaster]

That's the first ex WR diagram I've seen that has information about the lights. The rest of it is pretty standard.

 

Although it's of a Western location it was not an official drawing hence it has a number of features which would not be found on a 'box diagram (although they might well have been shown on a locking sketch).

[ChooChoo_Baloo]

Ok thanks for making clear RMweb's stance on copyright.

 

So in future, if I wish to copy and paste an image or passage of text, I must quote the respective author(s)?

 

 

[TheSignalEngineer]

Here is a digram from a box which illustrates some of the aspects (!) Original was in the Didcot museum. Not signed by the usual AK.

Nice one - selected discs as well. Another trick for saving levers.

[craigwelsh]

Ok thanks for making clear RMweb's stance on copyright.

 

So in future, if I wish to copy and paste an image or passage of text, I must quote the respective author(s)?

If they gave you permission to use it do quote them on that otherwise just link to the original location of the item.