Advise re. positioning of ground signals

[philsandy]

I have done some research regarding ground signals and would like some advise as to the correct positioning them.

Layout is a fictional single line thru station LMR circa 1960. 

Is the diagram above correct?

 

1  ground signal controlling exit from works sidings.

2  ground signal controlling entry to works sidings.

3  ground signal controlling entry to loop.

4  ground signal controlling exit from  loop.

5  yellow ground signal controlling exit from headshunt.

6  Would there need to be a ground signal here to control access to headshunt?

 

Also how many of these ground signals, if any  would require an arrow indicator  pointing left or right as required.

 

 

Edited January 6, 2019 by philsandy

[TheSignalEngineer]

As the main line is single and given the time in which it is set these will have a bearing on the method of working, signal box, ground frames etc which are required. This will also determine the signals required. It may be that you don't need any at all depending on what happens at each end of your sketch.

 

It looks as if trains can only run through on the main line. It doesn't look as if it is set up for trains to pass. Do you want to be able to put a goods train inside whilst another train goes through?  

[philsandy]

Thanks for your reply.

This is a small layout,  I was  limited with the space available, hence the single line. Although it's a through station the layout actually finishes at the station, the line disappears under a viaduct, just giving the illusion that it continues on.

At the other end  (LH side of  the sketch) the main line disappears under a bridge to a hidden fiddle yard. There are 3 works sidings which are in front of the concealed fiddle yard.

[IWCR]

You need to think what would be worked from the Signal Box.

3, 4 & 6 likely.

The turnout adjacent to 5 would likely be hand operated hence hand signalled.

The works siding shown would depend on how close to the station, Box worked and signalled as shown if within station limits, likely a ground frame released by the single line token if a distance away, in the latter case ground signals may be used or just hand signalling.

A ground signal is a running signal like all others hence 2 & 6 would need to be cleared to use the Main unless a Home or starter signal is there also to apply to the Main. 

 

Pete

[philsandy]

You need to think what would be worked from the Signal Box.

3, 4 & 6 likely.

The turnout adjacent to 5 would likely be hand operated hence hand signalled.

The works siding shown would depend on how close to the station, Box worked and signalled as shown if within station limits, likely a ground frame released by the single line token if a distance away, in the latter case ground signals may be used or just hand signalling.

A ground signal is a running signal like all others hence 2 & 6 would need to be cleared to use the Main unless a Home or starter signal is there also to apply to the Main. 

 

Pete

 

Thanks for your reply Pete.

I have amended the sketch of the layout to show the positions of signal box and the 2 semaphore signals.

The points to the works sidings are only 50 yards from the end of the station platform. 

[bécasse]

You need a yellow dolly at the crossover point on the loop leading towards the phantom main-line, given that you are actually working the layout as a terminus, there is no need to model this as a working signal. You also need a trap alongside dolly 4.

 

I am also doubtful about the shunt-ahead signal, with the works sidings, worked by the box, where they are you would need an advanced starter (doubtless off the modelled area) to protect the single line and thus shunt-ahead movements would be authorised by clearing the starter or by a hand-signal from the box. In practice the works sidings would almost certainly be worked by arriving freights, before they run straight into the headshunt (keeping the loco on the right end of the train for shunting). Moving to the platform road for running round would be the final move for freight workings. This sequence also means that you need a small RH subsidiary signal on the home (for direct admittance to the headshunt) and a pair of dollies (top to platform road, bottom to loop/headshunt) for no.6. I would dispense with 5 as 4 and its trap would protect movements from both the loop and the headshunt.

[philsandy]

Thank you for your reply.

 

You need a yellow dolly at the crossover point on the loop leading towards the phantom main-line, given that you are actually working the layout as a terminus, there is no need to model this as a working signal. You also need a trap alongside dolly 4.

 

 

Yes, I did think afterwards that a yellow ground signal was needed here there rather than  a red.

But I don't understand why  a trap point at 4 is needed?

 

 

I am also doubtful about the shunt-ahead signal, with the works sidings, worked by the box, where they are you would need an advanced starter (doubtless off the modelled area) to protect the single line and thus shunt-ahead movements would be authorised by clearing the starter or by a hand-signal from the box. In practice the works sidings would almost certainly be worked by arriving freights, before they run straight into the headshunt (keeping the loco on the right end of the train for shunting). Moving to the platform road for running round would be the final move for freight workings. This sequence also means that you need a small RH subsidiary signal on the home (for direct admittance to the headshunt) and a pair of dollies (top to platform road, bottom to loop/headshunt) for no.6. I would dispense with 5 as 4 and its trap would protect movements from both the loop and the headshunt.

 

Trains delivering to the works sidings would stop once the last wagon (ie. the brake van) has cleared the point, then the train would reverse into the works siding and drop off the wagons  (maximum of 6, .... it is a small layout,) so it would not go as far as the headshunt, only as far as the signal box , and the loco is already at the right end for shunting.

 

Trains delivering to the goods yard would run straight into the headshunt, then reverse and drop off the wagons in the goods sidings (shed) and then pick up empties.

The loco would then drop the empties in the loop, then run round, (this is why I thought  a shunt ahead signal was needed?) and pull the wagons away running in reverse.

Would a RH subsidiary signal on the Home for the headshunt still be required?

 

 

 and a pair of dollies (top to platform road, bottom to loop/headshunt) for no.6.

 

Ah yes, understand, that explains the bit I was unsure with.

So the ground signal at 2 (entry to works sidings), would this also require a pair of red ground signals, ie.  top: for works sidings, bottom: for main line,?

[bécasse]

I missed that last issue, mainly because I suspect that the real railway would have installed a ground frame (released by the signal box) rather than provide dollies and points actually worked by the box. As soon as you provide a ground frame (whether it is released by a box or by a single-line token/tablet/staff) close by the connection to the running line you no longer have to provide signals, in or out, and therefore providing a ground frame is cheaper (and, as a bonus, is easier to operate). The king lever on the ground frame usually works the facing point lock, so you need a two-lever GF.

You need a trap exiting the loop (towards your fiddle yard) because it counts as a siding and therefore the provision of a trap (and dolly) is mandatory. The normal arrangement was to provide the trap and adjacent dolly so that it covered exit from both the loop and the siding, the traps being incorporated into the pointwork if space was tight.

[RailWest]

I would agree about the use of a GF. Although you might envisage the siding as being only about 50 yards from the station, on your plan it "looks" a lot further out. I would be inclined to put the works siding on a GF unlocked by the token for the section and move the Down Home (2) in closer, putting it next to shunt 6 (which then would not need to be a 'running' shunt).

[philsandy]

As I understand it  ground disc signals are mechanically connected to the tie bar of the point, so when the point is switched the disc automatically rotates 45 degrees, and so are sited very close to the ends of the switch rails .

Where would a ground disc be positioned when the train is approaching the point from the trailing end?

I'm referring to ground disc 4 in the OP diagram, as trains exiting the headshunt and trains using the loop would be approaching a trailing point. Would it require a pair of red ground discs, and can they be sited several (10 's of ?) yards from the tie bar ?

I have attached a photo which hopefully will make things clearer.

[Grovenor]

As I understand it  ground disc signals are mechanically connected to the tie bar of the point, so when the point is switched the disc automatically rotates 45 degrees, and so are sited very close to the ends of the switch rails .

Signals like this have been used in the distant past but are not the usual UK arrangement. Normal practice is for each signal to have its own lever interlocked with but not linked to the points. The position adjacent to the point toe is used as the most efficient for shunting and it also allows simple provision of point detection when this is required.

Where would a ground disc be positioned when the train is approaching the point from the trailing end?

I'm referring to ground disc 4 in the OP diagram, as trains exiting the headshunt and trains using the loop would be approaching a trailing point. Would it require a pair of red ground discs, and can they be sited several (10 's of ?) yards from the tie bar ?

I have attached a photo which hopefully will make things clearer.

Signals at a trailing end such as you describe are usually located at the clearance point, ie where there is 6ft between the converging rails. this ensures that a train standing at the signal will not be hit by one passing on the adjacent track.

Note, however, that where such a signal leads from a siding to a passenger line there has to be a trap point, the signal will then be at the toe of the trap point.

 

ie, you need a trap point.

Regards

Edited January 9, 2019 by Grovenor

[RailWest]

Looking at the photo, it seems unclear to me whether or not there is enough room to get a trap point beyond the toe of the point leading into the yard and still maintain clearance with the main line. I suspect you may have to have one in each of the two routes out of the point into yard, worked together.

 

Others on this list may disagree :-)

 

Incidentally, the two sets of rodding seen in the photo are superfluous IMHO, as they lead to points that would be hand-worked, although the RH one could be cut back and used to work the aforementioned trap-point(s) instead.

[Grovenor]

Looking at the photo, it seems unclear to me whether or not there is enough room to get a trap point beyond the toe of the point leading into the yard and still maintain clearance with the main line. I suspect you may have to have one in each of the two routes out of the point into yard, worked together.

 

Others on this list may disagree :-)

Actually I agree, the toe of the existing turnout is inside the clearance position, a pair of single tongue traps within the turnout would be the best fit.

Regards

[philsandy]

Thanks for your replies.

 

Actually I agree, the toe of the existing turnout is inside the clearance position, a pair of single tongue traps within the turnout would be the best fit.
Regards

 

 

Becasse in post #6 did advise a trap here, I forgot to mention that in my last post.

 

Re. how a single tongue trap works, I've seen photos, does it simply derail, rather than divert away into a short siding?  

I'm unsure as how to fit it within the turnout, please can you explain further?

It would be purely cosmetic and not need to be a working trap.

 

 

 

Incidentally, the two sets of rodding seen in the photo are superfluous IMHO, as they lead to points that would be hand-worked, although the RH one could be cut back and used to work the aforementioned trap-point(s) instead.

 

Yes, something else I've learnt. I am going to uplift that point rodding.

 

[RailWest]

>>>>>> how a single tongue trap works, I've seen photos, does it simply derail, rather than divert away into a short siding?  

 

A single-tongue trap simply derails (away from the main line, of course!). A double-tongue trap does the same thing, but sometimes is extended into being in effect a very short point, or even implemented by an actual point which leads to a spur and/or sand-drag. But the single-tongue would do for you. It can be cosmetic, but really it's not too hard to make it work if you've got basic skills for building point-work.

 

>>>I'm unsure as how to fit it within the turnout, please can you explain further?

I'm sure there are others here who can draw better sketches than me or may even know a link to a prototype drawing/photo :-)

Re. how a single tongue trap works, I've seen photos, does it simply derail, rather than divert away into a short siding?  

I'm unsure as how to fit it within the turnout, please can you explain further?

[RailWest]

>>>Yes, something else I've learnt. I am going to uplift that point rodding....

 

If you are going to fit rodding - well done that man! - then it is worth trying to get the basics correct. For example, no sign of any compensator in that long run. One difficulty in a  small scale is trying to get it sufficiently straight and level so that it looks right - I recall one layout in the model press not long ago where the effect looking down from above was OK, but the photographs taken almost at 'ground level' showed something of a cross between a corkscrew and a roller-coaster !