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Checking that a tail lamp is present

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ryan125hst

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In areas that are signalled using Absolute Block, part of the duty of the signaller is to look for the tail lamp at the rear of the train. The presence of the tail lamp indicates that the train is complete and therefore the 'Train Out Of Section' bell code can be sent to the adjacent signal box. This is required due to there usually being no track circuits between signal boxes in absolute block signalled areas, and at one time, many freight trains were unfitted, meaning that they didn't have an automatic brake throughout the train.

However, some signal boxes control more than just a couple of running lines. It's possible for pair of slow lines to supplement the fast lines for example, and there may be additional lines such as goods lines to add to the mix as well. With multiple lines to watch, how does the signaller make sure they are able to check the tail lamp on every passing train? Surely it is possible that if two or more trains are passing at such a time that the rear of multiple trains is passing the signal box at the same time then it will be difficult to check for the presence of the lamp on every train? Could there be instances where a train closer to the box obscures the view of trains on lines further away from the box? And what about boxes where a line passes behind the box as well as in front?

What happens if a signaller misses the back of the train and therefore can't confirm it has left the section complete?
 
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Gloster

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Even on double-track you could miss the tail-light if there was a train in the way at the crucial moment. Normal practice was to hold the block, i.e. not give Train Out of Section or return the block indicator to Normal (and tell the signalman why), until you had received TOS from the next box. Not quite by the book, which I think said you had to treat it as a Train Passed without Taillamp, but a compromise between bringing the whole job to a stand and chancing that all was fine. Your choice of exactly what you did was affected by factors such as type of train, what other trains were about, gradients, etc.
 

Revaulx

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The collision at Shrivenham in 1936 was a result of an unfitted freight becoming divided and the signalman issuing TOS without having ascertained that a tail lamp was present; I think he had been distracted or had his view blocked by a train passing in the opposite direction.

His mistake was compounded by the guard of the freight not realising that most of his train had gone off without him. He assumed they had stopped at a signal and took no action to prevent, or at least mitigate, a collision.
 

MotCO

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How can you do this with regional signal centres (or whatever they're called)? Or don't they have any Absolute Blocks?
 

Gloster

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How can you do this with regional signal centres (or whatever they're called)? Or don't they have any Absolute Blocks?
Regional Signalling Centres will be Track Circuit Block or similar. You cannot have Absolute Block without the presence of signalman as they make a visual tail light check to see that the train is complete, as there are not continuous track circuits to indicate that a train has cleared a section of line by not showing occupied.
 

father_jack

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A beet train derailed in Ireland in the 1990s, the driver went back and uncoupled at the last unaffected wagon, put the tail lamp on and continued leaving the rest of the wagons strewn all over the formation !!! Thankfully he reported it to the signaller at the next block post. What does "train complete" mean in that case ?
 

Tomnick

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Regional Signalling Centres will be Track Circuit Block or similar. You cannot have Absolute Block without the presence of signalman as they make a visual tail light check to see that the train is complete, as there are not continuous track circuits to indicate that a train has cleared a section of line by not showing occupied.
There are a couple (maybe not even a couple now!) of exceptions, albeit maybe not in ROCs but certainly in similar establishments. Manchester East SCC works AB to Dinting (and also worked AB to Ashton Moss North before that box was abolished?), with 'train arrived complete' plungers provided at the first station inside the home signal and, IIRC, at the next signal too. There's plenty of tail lamp cameras around too, one example in a reasonably big box being in Worksop PSB for the section from Shirebrook (or Elmton & Creswell if it's switched in). There's always the possibility too that an AB section is track circuited throughout - Halifax to Bradford (Mill Lane) was like this, with the home signal being a few miles in rear of the box at the Bradford end!
 

ryan125hst

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Even on double-track you could miss the tail-light if there was a train in the way at the crucial moment. Normal practice was to hold the block, i.e. not give Train Out of Section or return the block indicator to Normal (and tell the signalman why), until you had received TOS from the next box. Not quite by the book, which I think said you had to treat it as a Train Passed without Taillamp, but a compromise between bringing the whole job to a stand and chancing that all was fine. Your choice of exactly what you did was affected by factors such as type of train, what other trains were about, gradients, etc.

I thought that might have been the case. It's probably not a major issue on quieter lines but would be a major inconvenience on busier routes. You have to hope the next signalman manages to see the lamp! What happen if the next box is worked by TCB? Presumably you have no choice but to stop the job until you've confirmed the train is complete?
How can you do this with regional signal centres (or whatever they're called)? Or don't they have any Absolute Blocks?
In Absolute Block areas, there aren't normally track circuits between the signal boxes and so the safety of trains depends on a system of bell codes and block instruments. As the train isn't detected continuously, it relies on the tail lamp being on the back of the train to prove that some of the train hasn't been left behind which would result in a collision if another train was accepted into that section. With Track Circuit Block which is used in areas that are controlled by Power Signal Boxes (PSBs) and Regional Operating Centres (ROCs) trains are always being detected by track circuits and so if the train became divided, the vehicles that are left behind would cause the track circuits they are occuping to show as occupied and the signals behind this would remain at danger.

The Signal Box website explains how Absolute Block works if you are interested: https://signalbox.org/block-system/
There are a couple (maybe not even a couple now!) of exceptions, albeit maybe not in ROCs but certainly in similar establishments. Manchester East SCC works AB to Dinting (and also worked AB to Ashton Moss North before that box was abolished?), with 'train arrived complete' plungers provided at the first station inside the home signal and, IIRC, at the next signal too. There's plenty of tail lamp cameras around too, one example in a reasonably big box being in Worksop PSB for the section from Shirebrook (or Elmton & Creswell if it's switched in). There's always the possibility too that an AB section is track circuited throughout - Halifax to Bradford (Mill Lane) was like this, with the home signal being a few miles in rear of the box at the Bradford end!
Does Manchester East SCC have a block bell?

Were 'train arrived complete' plungers common back in the days when AB was more commonplace or are they a more modern idea? I've heard of tail lamp camera - clearly that's a modern change to deal with fewer signal boxes.
 

Gloster

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I thought that might have been the case. It's probably not a major issue on quieter lines but would be a major inconvenience on busier routes. You have to hope the next signalman manages to see the lamp! What happen if the next box is worked by TCB? Presumably you have no choice but to stop the job until you've confirmed the train is complete?

In Absolute Block areas, there aren't normally track circuits between the signal boxes and so the safety of trains depends on a system of bell codes and block instruments. As the train isn't detected continuously, it relies on the tail lamp being on the back of the train to prove that some of the train hasn't been left behind which would result in a collision if another train was accepted into that section. With Track Circuit Block which is used in areas that are controlled by Power Signal Boxes (PSBs) and Regional Operating Centres (ROCs) trains are always being detected by track circuits and so if the train became divided, the vehicles that are left behind would cause the track circuits they are occuping to show as occupied and the signals behind this would remain at danger.

The Signal Box website explains how Absolute Block works if you are interested: https://signalbox.org/block-system/

Does Manchester East SCC have a block bell?

Were 'train arrived complete' plungers common back in the days when AB was more commonplace or are they a more modern idea? I've heard of tail lamp camera - clearly that's a modern change to deal with fewer signal boxes.
For the first point: if you were a fringe box, you just used your judgement. There was no hard and fast rule, as you were already bending the rules.

Train arrived plungers have been around for some time, but most commonly in locations where a train would terminate without passing the box or spend a long time within the station limits before passing it. They would generally be used where this was a regular occurrence. The alternative was a ‘phone call: “Signalman. This is the guard of 1B34 reporting that the train has arrived complete with taillamp”, or, “Bobby, we’re inside”.
 

Ashley Hill

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Tail lamp cameras have been mentioned. These can also enable a signaller to clear out before the train passes his box . Truro on the up is an example. Also mirrors were/are used. Teignmouth had one opposite the box to see the lamps of up services if a down one was in the platform or passing through simultaneously.
 

Gloster

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Tail lamp cameras have been mentioned. These can also enable a signaller to clear out before the train passes his box . Truro on the up is an example. Also mirrors were/are used. Teignmouth had one opposite the box to see the lamps of up services if a down one was in the platform or passing through simultaneously.

There was also a mirror on the footbridge at St Germans for Up trains. There the box was in the Down station buildings, so any train in the Down platform would completely block the view.
 

edwin_m

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I thought that might have been the case. It's probably not a major issue on quieter lines but would be a major inconvenience on busier routes. You have to hope the next signalman manages to see the lamp! What happen if the next box is worked by TCB? Presumably you have no choice but to stop the job until you've confirmed the train is complete?
Less of an issue these days as most busier routes have Track Circuit Block.

There's also this accident showing how the system could break down quite spectacularly, fortunately without serious consequences this time: https://www.railwaysarchive.co.uk/documents/MoT_Weekday1955.pdf
In thick fog the 6.45 a.m. express passenger train from Leicester Central to Manchester London Road collided at low speed with the rear portion of an empty mineral train which had become divided from the front portion and had been standing in the section for three-quarters of an hour.
...
The absence of the tail lamp should have been discovered at each of the signal boxes which the incomplete train passed, and immediate action taken in accordance with the Block Regulations by the signalmen concerned.

The signalman at Weekday Cross was primarily responsible. He failed to watch the freight train with sufficient attention whilst it passed his box, particularly in view of the difficulties of visibility caused by the fog, and assumed that it had passed complete. He then accepted the express while the rear part of the Freight train remained in the section bidden by the fog.

The signalmen at Nottingham Victoria South and Nottingham Victoria North boxes might have been excused for failing to see the tail lamp in the conditions obtaining at their respective boxes, but they cannot he excused for failing to take the proper action when they did not see it. I do not accept their statements that they thought they saw a tail lamp on this train.

The signalman at Carrington was obviously not taking his duty of checking tail lamps as seriously as he should for he had not told his groundman to stand on the far side of the Down line so that he could see at close range the tail lamps of trains passing on that line. He had not therefore been convinced by the groundman's statement that he had not seen the lamp.

I can find no excuse for the groundman at New Basford stating that he saw a tail lamp on this incomplete train. Even at this late stage a report to Control from his signalman might have been in time to prevent the accident.

The signalman at Bagthorpe junction was at fault in not taking prompt action when his groundman reported the tail lamp as missing, though in the circumstances his failure had little bearing on the accident.

I have some sympathy with the guard in his predicament, and I am satisfied that he was alert, but nevertheless I think that he showed a lack of initiative and made an error of judgment in not continuing his inspection along the train once he had begun, until he had discovered the cause of the delay.
 

Tomnick

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Does Manchester East SCC have a block bell?

Were 'train arrived complete' plungers common back in the days when AB was more commonplace or are they a more modern idea? I've heard of tail lamp camera - clearly that's a modern change to deal with fewer signal boxes.
Yes, it had one block bell for each section (now just Dinting remains). Photos LNW (North) / Manchester Area (including Stockport) / Manchester East / 2016 June | Signalling Photos]here[/url]. Tail lamp cameras aren't just provided to deal with fewer signal boxes (although that's a common use, e.g. where a box now controls both ends of a set of loops and thus can't see the back of an arriving train from the far end) - Totley Tunnel East SB has one because the tail lamp of a long freight train standing at York ROC's first signal won't have passed the box but will be beyond the clearing point.
 

83G/84D

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Tail lamp cameras have been mentioned. These can also enable a signaller to clear out before the train passes his box . Truro on the up is an example. Also mirrors were/are used. Teignmouth had one opposite the box to see the lamps of up services if a down one was in the platform or passing through simultaneously.
Truro lost it's tail lamp camera when the lines west to Camborne were converted to TCB. The camera now resides on the up line west of Camborne on the AB section between St Erth & approximately Gwinear Rd.
 
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