A layout shunt signal question

[The Stationmaster]

As drawn you have overlapping blocks (the AS is the section signal - pointless having it if it's not). So if you have accepted a down train under reg 4 you cannot accept an up train even under a warning acceptance because you have fouled your clearing point for the up train and you are not clear to the Home as required by reg 5.

 

If the AS is removed or repositioned to be in advance of the up Home then you can accept an up train to the Home (this does require a mod to the clearing point ie it is not 440 yds in advance of the AS but is at the AS) under the Warning acceptance.

 

Alternatively you accept both trains under a warning acceptance and hold the UP train at the Home to permit the Down train to enter the loop (strictly not a loop more a siding as there is no platform and hence this cannot be a passing post - like Highley).

It's about time all this bloomin' nonsense stopped and we got down to some basics (with apologies to the OP who has very sensibly moved on).

 

Firstly the station was not signalled as a crossing point as originally presented but as an intermediate location on a single line with a siding - the siding being in loop format (which is probably where the trouble started.  The only way trains could be crossed there under most of the single line Block Regulations is for one to arrive and be shunted to a siding before the other one is accepted - if the situation is other than that once one train has been accepted the Regulations do not permit one to be accepted from the opposite direction.  And whatever signals are there, be it one stop signal in each direction or three it makes no difference - if a Down train has been accepted or is in section an Up train cannot be accepted, and vice versa - see post No.13 above.

 

The Advance Starter is an irrelevance as far as acceptance is concerned on a single line - what counts are the Home Signals (which must read to different sides of the loop, i.e they cannot conflict in route terms) and the next signal in advance of the Home Signal at the departure end of the loop - it, of course, being the Clearing Point at a crossing place.  The only real purpose served by an Advance Starting signal is to act as a positive visible limiting point for shunting movements being made beyond the crossing loop and/or out onto the single line  (or, if there is an auxiliary token instrument, allowing a train forward to wait acceptance and clear the loop).

 

So let's not mess around trying to do something the track layout and signalling was clearly not intended to do - it is a single line with a looped siding and as signalled cannot work as a passing place because it cannot comply with the normal Block Regulations for token working.  And it's certainly not a place where I (and I hope my former colleagues with similar responsibilities)  would even consider authorising a Warning Acceptance in order to get round the lack of proper signalling and I certainly don't think it's the sort of situation which even entered our heads when we decided to retain the equivalent of the Warning Acceptance when we were reviewing the Block Regulations in the mid 1980s.

[ForestPines]

So let's not mess around trying to do something the track layout and signalling was clearly not intended to do - it is a single line with a looped siding and as signalled cannot work as a passing place because it cannot comply with the normal Block Regulations for token working. And it's certainly not a place where I (and I hope my former colleagues with similar responsibilities) would even consider authorising a Warning Acceptance in order to get round the lack of proper signalling and I certainly don't think it's the sort of situation which even entered our heads when we decided to retain the equivalent of the Warning Acceptance when we were reviewing the Block Regulations in the mid 1980s.

I suspect people are being seduced by the example of Highley, which nowadays has both unusually short Clearing Points and Regulation 5 authorised, to cope with modern SVR traffic requirements. Signalmen there are still prohibited from accepting two passenger trains or two trains under Regulation 4 simultaneously, of course.

[Kylestrome]

Thank you Stationmaster. You have understood my original intentions although, I must admit, I didn’t make them entirely clear in my first post.

 

It was never my wish to pass trains at this station. The only reason I included advance starter signals on the plan, which would in any case be ‘off-scene’, was to define the station limits. I thought that they would be necessary, in a real situation, because shunting moves would take place beyond the starter signals. I didn’t realize I was opening quite such a large can of worms!

 

Anyway, I’m still following this discussion with interest, although I’m coming to the conclusion that having no signals would be acceptable (and even desirable   ) , if this station was in the middle of a block section and a train was in possession of the token. Just to be absolutely clear, that would mean that no running signals and no shunting signals are necessary, right?

 

 

Confused? Nah, just a little bewildered ... 

[The Stationmaster]

Thank you Stationmaster. You have understood my original intentions although, I must admit, I didn’t make them entirely clear in my first post.

 

It was never my wish to pass trains at this station. The only reason I included advance starter signals on the plan, which would in any case be ‘off-scene’, was to define the station limits. I thought that they would be necessary, in a real situation, because shunting moves would take place beyond the starter signals. I didn’t realize I was opening quite such a large can of worms!

 

Anyway, I’m still following this discussion with interest, although I’m coming to the conclusion that having no signals would be acceptable (and even desirable   ) , if this station was in the middle of a block section and a train was in possession of the token. Just to be absolutely clear, that would mean that no running signals and no shunting signals are necessary, right?

 

 

Confused? Nah, just a little bewildered ... 

In some ways it depends what you want on your layout.  You are absolutely right with your ground frame solution and even more so right for the late/post-steam age.

 

In earlier times the station might well have had a signalbox and signals - but no need for Advance Starters to define Station Limits as shunting outside Station Limits was common at single line stations and was catered for quite readily within the Block Regulations as there was frequently (usually) no alternative.  In fact once you want to make a movement outside the protection of the Home Signal, i.e. in rear of it, there is a requirement to block back so the presence of an Advance Starting Signal is effectively an irrelevance except for the reasons I outlined above.

 

Station Limits is rather unusual at a single line crossing station because it can be, and very often was, different in each direction and the two directions were basically independent of each other in terms of applying the Regulations in respect of such things as Blocking Back.  Once upon a time in the very dim and distant past some Company's single line Block Signalling Regulations included provision for 'Shunting Into Forward Section' but they eventually, and very logically, realised such a Regulation was unnecessary as the same facility was offered, with even greater flexibility, by using a 3-3 Block Back; it is, for example, roundly 100 years since the GWR abolished Shunting Into Forward section in its single line Regulations. 

[TheSignalEngineer]

In some ways it depends what you want on your layout.  You are absolutely right with your ground frame solution and even more so right for the late/post-steam age.

 

In earlier times the station might well have had a signalbox and signals - ............................. 

Continuing the theme of changes/rationalisation, it could well be that the layout did have full signalling at one time, but signals had been removed. The signal box could have been retained to work the points with the frame released by inserting the token into a lock on the end. This would release the mechanical interlocking and allow the points to be moved as required fro shunting. 

 

A further idea for Mike to comment on:-

 

if you wanted to pass a train with the freight on-scene would be to provide 'Shut Inside' facilities. This would require an auxilliary token machine at the signal box whereby the driver of the freight train could insert the token with the train ih the siding and the frame locked to free up the section. A subsequent train could then run through and when it had cleared the single line the driver could get the token released again to carry on shunting, go on to the next station or return whence he came.

[Kylestrome]

Continuing the theme of changes/rationalisation, it could well be that the layout did have full signalling at one time, but signals had been removed. The signal box could have been retained to work the points with the frame released by inserting the token into a lock on the end. This would release the mechanical interlocking and allow the points to be moved as required fro shunting. 

 

That is the plan, especially as the box is already built!

 

 

if you wanted to pass a train with the freight on-scene would be to provide 'Shut Inside' facilities. This would require an auxilliary token machine at the signal box whereby the driver of the freight train could insert the token with the train ih the siding and the frame locked to free up the section. A subsequent train could then run through and when it had cleared the single line the driver could get the token released again to carry on shunting, go on to the next station or return whence he came.

 

That sounds like a prototype for everything. Almost like Rule No. 1

[The Stationmaster]

Continuing the theme of changes/rationalisation, it could well be that the layout did have full signalling at one time, but signals had been removed. The signal box could have been retained to work the points with the frame released by inserting the token into a lock on the end. This would release the mechanical interlocking and allow the points to be moved as required fro shunting. 

 

A further idea for Mike to comment on:-

 

if you wanted to pass a train with the freight on-scene would be to provide 'Shut Inside' facilities. This would require an auxilliary token machine at the signal box whereby the driver of the freight train could insert the token with the train ih the siding and the frame locked to free up the section. A subsequent train could then run through and when it had cleared the single line the driver could get the token released again to carry on shunting, go on to the next station or return whence he came.

Very much a plausible and very workable situation.  Just doing a quick check from an old Sectional Appendix there were 4 such places on the Aberdare branch in 1973 and at one of them separate ground frames at different ends of the same set of looped sidings both had Shut-In facilities with an Intermediate (auxiliary) Token Instrument.  In addition there was a junction where a freight only branch left a passenger line and it too had a ground frame with a Shut-In facility - a freight could come down the single line, leave it at the junction (worked by a ground frame) and shut-in on the branch thus enabling a passenger train to work down to the terminus and back up while the freight was shut-in on the branch.

 

I'm not aware of any locations where it was done using a signalbox lever frame but they wouldn't necessarily show up in an Appendix as such as when the train has shunted clear of the running line the token would be surrendered to the Signalman and he would place it into the intermediate instrument enabling another token to be released for the single line section.

[RailWest]

>>>I'm not aware of any locations where it was done using a signalbox lever frame.....

In which case, you're forgetting Frome West GF then Mike :-) There was an intermediate EKT instrument there in the old SB.

[The Stationmaster]

>>>I'm not aware of any locations where it was done using a signalbox lever frame.....

 

In which case, you're forgetting Frome West GF then Mike :-) There was an intermediate EKT instrument there in the old SB.

It's an age thing Chris - although it was all in a rather sorry state by the time of my arrival.

[sussexpickle]

I'd personally have distant - home - section signal in each direction and have 2 groundframes within the station limits.