Combined distant and starter signals

[ColHut]

G'day All, a question on distant and starter signals on the same pole, and their use with Block signalling.

 

I understand that if the distance between the last stop signal of the box in rear was less than half a mile form the first stop signal of the box in advance, then it was permissible to place the distant of the latter on the last stop signal of the former.  The distant does not need to be slotted with the stop signal if the distance between the two stop signals is more than a quarter of a mile.   (I believe that there were certainly many cases where where such slotting with one or more stop signals did occur but that is not what i am interested in here).

 

Is my understanding of the above correct?

 

If (and it is a big if ) then circumstance may occur (maybe the line has been busy and a train held at the box in rear), where a train may well be accepted by the box in advance (line clear to the relevant clearing point), and and the signalman in rear lower his signals for the train to leave (and send "Train entering Section")  before the distant has been pulled off because the signalman at the box in advance has not had time to offer the train to the next box along again and so avoid such unnecessary delay by having the train proceed whilst expecting to stop at the next signal.

 

My point I think is that  where there is some distance between the last stop signal and the next distant, there is more time to enable uninterrupted or higher speed running.

 

Did I get this right?

 

[micknich2003]

A distant arm placed under a stop arm will always be "Slotted or Controlled". Otherwise it would be possible to have the Stop arm at Danger and the Distant at Clear.

[ColHut]

Dear Mick,

 

But what is the problem with that?

 

...Stop arm at Danger and the Distant at Clear.

 

Cannot proceed into the next section but section ahead is clear through - okay I think I answered that one myself.   That would be a silly combination

 

But okay to have stop arm off and the distant at caution?

 

If this was a night-school course I'd happily attend!

[phil-b259]

A distant arm placed under a stop arm will always be "Slotted or Controlled". Otherwise it would be possible to have the Stop arm at Danger and the Distant at Clear.

 

And while its not so much of an issue in daylight, despite things like route knowledge being needed, it doesn't take a genius to realise the very real and present danger that a driver might misread the signals (especially with the feeble light given out by oil lamps) and crash into another train. This is why the regulations are quite strict and have been for many decades. The distant MUST NOT come 'off' unless any associated stop signals mounted on the same structure are also showing a proceed. Furthermore the signalling must be arranged such that if the stop signal is subsequently replaced to danger the distant MUST also revert to the 'on' position automatically

 

As for delaying trains, thats where timetabling comes in and if trains are that frequent that the signalman in box cannot clear his distant before trains reach it then there are too many trains trying to be run on that line. Either you reduce the train numbers or increase the capacity by adding more block sections to even things out, or go for multiple aspect signalling where you can make every stop signal effectively be a distant as well.

[ColHut]

Thanks Phil - that makes sense

Regards

[The Stationmaster]

G'day All, a question on distant and starter signals on the same pole, and their use with Block signalling.

 

I understand that if the distance between the last stop signal of the box in rear was less than half a mile form the first stop signal of the box in advance, then it was permissible to place the distant of the latter on the last stop signal of the former.  The distant does not need to be slotted with the stop signal if the distance between the two stop signals is more than a quarter of a mile.   (I believe that there were certainly many cases where where such slotting with one or more stop signals did occur but that is not what i am interested in here).

 

Is my understanding of the above correct?

 

 

Not quite.  The distance which matters is the braking distance between the Distant Signal and the outermost Home Signal to which it applies and that could be, even in steam days, a lot further than half a mile.  This also means that the Distant Signal could be below far more stop signals at the 'box in rear than just the Section Signal - in fact it might also be beneath all the stop signals applying to that line at the 'box in rear - especially if the section is only half a mile long.

[micknich2003]

Phil B, thanks for your follow up, you have put things in to far better perspective.

[ColHut]

Thanks Mike

 

So there were set distance set out in some sort of signalling engineering rule book based on line speed or at least expected line speed?

 

Regards

[TheSignalEngineer]

..........................................  This also means that the Distant Signal could be below far more stop signals at the 'box in rear than just the Section Signal - in fact it might also be beneath all the stop signals applying to that line at the 'box in rear - especially if the section is only half a mile long.

Prior to Saltley PSB, to get a green in New Street's last signal at Grand Junction needed all signals off at Exchange Sidings, Landor St Jn, Saltley Jn, Saltley Sidings, and Washwood Heath Sidings No.1. The latter required Line Clear from Washwood Heath Jn.

[LNERGE]

[TheSignalEngineer]

Thanks Mike

 

So there were set distance set out in some sort of signalling engineering rule book based on line speed or at least expected line speed?

 

Regards

If you don't mind a long read try this, which is the current document. http://www.rgsonline.co.uk/Railway_Group_Standards/Control%20Command%20and%20Signalling/Railway%20Group%20Standards/GKRT0075%20Iss%202.pdf

 

If you are in a hurry and just want to see the distances go straight to Appendix A and start from there.

 

Searching withdrawn documents on the site will give you the standards back to about the 1970s, but it's a bit hit and miss. The composite table hasnot changed significantly except higher speeds being added.

 

Eric

 

hp13.jpg

Seen that done, the culprit got 3 days unpaid holiday.

[Eggesford box]

Not quite what you where asking but where boxes where close together the normal mode of signalling could be modified so that the 'Is line clear' was asked to the box in advance on receipt of the 'Is line clear' bellcode from the box in the rear instead of waiting for the train entering section bellcode so that the signalmen physically had time to pull off without giving the train a check at the distant signals. 

[phil-b259]

hp13.jpg

 

Any more details because every single thing I have been taught says that picture shouldn't be allowed to exist!

 

Mind you I suppose if the "signal machine" got jammed then it might happen - but in that case the lack of the signal having returned to 'on' would cause other things to not happen to protect the failure

[TheSignalEngineer]

The instance I saw was where two lines converging had similar signals standing parallel and fed from the same location. The distant motor feeds were cut by a contact proving the Home arm off, and not mechanically slotted. The installer got the cables to the motors crossed during a changeover.  

[The Stationmaster]

Any more details because every single thing I have been taught says that picture shouldn't be allowed to exist!

 

Mind you I suppose if the "signal machine" got jammed then it might happen - but in that case the lack of the signal having returned to 'on' would cause other things to not happen to protect the failure

It does happen (or should that be 'did') where the distant arm was motor worked and there was no mechanical slotting arrangement and the motor was somewhat on the slow side putting back the arm to caution.  reading S&T works had a special test rig for the Westinghouse signal motors (called backing machines in the works) to ensure they were operating within specified limits after overhaul and that included the time they took to replace the signal arm to the 'on' position.

 

 

Prior to Saltley PSB, to get a green in New Street's last signal at Grand Junction needed all signals off at Exchange Sidings, Landor St Jn, Saltley Jn, Saltley Sidings, and Washwood Heath Sidings No.1. The latter required Line Clear from Washwood Heath Jn.

The interesting part of that kind of thing was working it all out in the first place as you needed to have a 'hold point' (for want of a better term) beyond which 'Is Line Clear?" was not asked if there was a succession of closely spaced 'boxes, the art then was to get the 'train approaching' bell signals sent over the right number of successive sections to ensure that a train was asked forward from the 'hold point' in order to avoid it getting a distant check at that 'box.  As far as the Signalmen were concerned all they need to do was what the Signalbox Special Instructions told them, the chap who'd done all the work devising it might never even have seen the sky over the 'boxes concerned. 

[micknich2003]

 Here's another one, Beverley, June 1983.

[LNERGE]

hp13.jpg

This photo was taken as Harringay Park box was being switched in. I knew as the mechanical home was replaced the motor operated distant would take a moment to start to wind back. All i had to do was tell the Bobby i was lurking ready with the camera and press the shutter at the right time..

 

Edit to add.. I liked it so much i now have this arrangement at home on one of my boxes..

[RailWest]

Coincidentally last week I was shown a picture (do not have the copyright so can not post it here) of the Down Home at Teignmouth in the 'on' position, but with the motor-worked (outermost) Down Distant for Teignmouth Old Quay firmly in the 'off' position.

[Edwin_m]

Not quite.  The distance which matters is the braking distance between the Distant Signal and the outermost Home Signal to which it applies and that could be, even in steam days, a lot further than half a mile.  This also means that the Distant Signal could be below far more stop signals at the 'box in rear than just the Section Signal - in fact it might also be beneath all the stop signals applying to that line at the 'box in rear - especially if the section is only half a mile long.

Going beyond this a little, at certain closely-spaced boxes local instructions didn't allow the signalman to clear his own distant unless the distant for the next box was clear.  I believe this was sometimes done by interlocking the boxes but often just relied on the signalman obeying the instruction.  If the signalman couldn't see the next box's distant then there would be an indicator in his own box worked by the next box's distant lever.  Failure to do this correctly resulted in an accident to a Western Pullman set on the outskirts of Birmingham, but the exact place escapes me at present. 

[bécasse]

While a motor-worked distant under a wire-worked stop signal was one of the rarer combinations, it wasn't that unusual, and where it did occur the combination seen above was likely to happen most times that a train went past, albeit only for a fleeting moment...... and I have seen it happen, albeit even more briefly, where both arms were motor-worked.

 

I wonder who will be the first to replicate it using the new Peco servo drives?

[micknich2003]

Years ago, when I was signalman at Beverley Cherry Tree, the arrangement was as mentioned above. Here is a picture of the signal/slot repeaters, the three boxes involved, Beverley, Cherry Tree and Beverley North were approx 600 yards apart. To complicate matters, Beverley's Distant was slotted as Cherry Tree's Distant, Beverley's Starter was slotted as Cherry Tree's Home, and Beverley North had Outer and Inner Distants. The Outer Distant was motor worked and under Beverley's Starter/Cherry Tree's Home, the Inner Distant was under Cherry Tree's Starter. Despite having a "Needle" repeater, the slotted Beverley/Cherry Tree Distant was a colour light.

[beast66606]

What goes up also goes down

 

 

(Wrexham)

[beast66606]

  If the signalman couldn't see the next box's distant then there would be an indicator in his own box worked by the next box's distant lever. 

 

Here's one in my collection (an LNWR / LMS one) - this was provided in Green Lane Junction* cabin and the signalman there would only pull off his down fast distant when Blackpool Street had cleared the down distant

 

 

 

In other local (to Green Lane Junction) face discs were provided which performed the same job. I also own on of those but I don't have it with me so I can't photograph it, imagine a disc with the words "Down Fast Distant Off" on it, it was tilted to display these words when the relevant signal was cleared.

 

 

 

* Green Lane Junction was on the Birkenhead Joint (GWR/LNWR) between Birkenhead Woodside and Hooton - it controlled the access to Birkenhead Mollington Street shed, and the last one closed in 1985 - although there were several boxes which carried this name over the years.

[The Stationmaster]

Going beyond this a little, at certain closely-spaced boxes local instructions didn't allow the signalman to clear his own distant unless the distant for the next box was clear.  I believe this was sometimes done by interlocking the boxes but often just relied on the signalman obeying the instruction.  If the signalman couldn't see the next box's distant then there would be an indicator in his own box worked by the next box's distant lever.  Failure to do this correctly resulted in an accident to a Western Pullman set on the outskirts of Birmingham, but the exact place escapes me at present. 

There were several ways of coping with this situation but - certainly in the BR period post 1968 - I believe the Western was the only Company/Region which latterly had a Block Regulation written specifically for it.  This (Regulation 4A, known to many of us as '4 big A' to distinguish from clause a of Regulation 4) disappeared from the Block regulation books a long time ago as it didn't survive the transition to the first truly national book in 1972.  However that wasn't the end of it as it lingered on in Signalbox Special Instructions at places where it was needed and I saw it still in use at Shrewsbury in the 1990s - it might still survive there?

 

One amusing feature of the Regulation was that because it was used where Distant Signals weren't interlinked between successive 'boxes the 'instruction' not to clear a Distant at the 'box at the rear end of the short section(s) was given by a special bell code when the 'box in advance accepted a train but could not clear its stop signals;  the Bell Code was noted in the Regulations as 'Line Clear to Clearing Point Only', an interesting variation on a 'straight' ABR 4 acceptance which, of course, also required the line to be clear to the Clearing Point. 

[Eggesford box]

Going beyond this a little, at certain closely-spaced boxes local instructions didn't allow the signalman to clear his own distant unless the distant for the next box was clear.  I believe this was sometimes done by interlocking the boxes but often just relied on the signalman obeying the instruction.  If the signalman couldn't see the next box's distant then there would be an indicator in his own box worked by the next box's distant lever.  Failure to do this correctly resulted in an accident to a Western Pullman set on the outskirts of Birmingham, but the exact place escapes me at present. 

Knowle and Dorridge 15th August, 1963. If you want to google it there is the full accident report via the railwayarchives website