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Signaling into depot


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Good morning, advice please.

layout is single track modern image to small station no run round. with a turnout just before station into maintenance depot what would the right signaling be for the turnout into depot. Would I use a 2 aspect with feather or twin aspect one for station and one for yard entry, or have I got it completely wrong (more than likely)  and need something else

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Entry into a depot will never be a main aspect, always a position light subsidiary signal. Any main aspect signal showing better than red means the line is completely clear as far as the next main aspect signal - unless it is into a terminating platform road where the buffer stops equate to a red signal. Entry into a depot can never be guaranteed to be clear to the next main signal or buffer stop so a position light signal under the red main aspect means that you can proceed as far as the line is clear or you reach a stop board or a shunter with further instructions. 
 

Andi

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1 hour ago, Dagworth said:

Entry into a depot will never be a main aspect, always a position light subsidiary signal. Any main aspect signal showing better than red means the line is completely clear as far as the next main aspect signal - unless it is into a terminating platform road where the buffer stops equate to a red signal. Entry into a depot can never be guaranteed to be clear to the next main signal or buffer stop so a position light signal under the red main aspect means that you can proceed as far as the line is clear or you reach a stop board or a shunter with further instructions. 
 

Andi

 

Hi,

 

You can have a main aspect into a depot, depends on what space you have and what Ops want, see below for an example (diagram from my book).

 

2142263290_Figure135.jpg.6fc8544e56a123fe0970736e5123a183.jpg

 

If you have enough space to have a reception line (only needs to be Loco / Train length + ~20m), and if Ops want the main running line to be clear quickly, you can put a Stopboard ( or a fixed red with position light if you want to be really fancy) between the end of your reception line and start of the depot, fit full train detection and have a main aspect move into the reception line.

 

If you don't have that, or Ops aren't willing to pay for it then, yes you have a position light into the Depot.

 

Simon

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7 minutes ago, The Stationmaster said:

Simon,

 

Can you now have a main aspect reading to a stop board?    I thought that a main aspect has to read to a proved signal, i.e. a fixed red in this situation?  (I must admit it's along while since I read the latest version of the Signalling Principles)

 

Hi Mike,

 

Yes, that's okay, I can't find the standard that says it, but I certainly know that you can do it (and I have done it on a couple of schemes), as long as there's full train detection along the whole route.

 

Simon

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24 minutes ago, The Stationmaster said:

Simon,

 

Can you now have a main aspect reading to a stop board?    I thought that a main aspect has to read to a proved signal, i.e. a fixed red in this situation?  (I must admit it's along while since I read the latest version of the Signalling Principles)

 

But doesn't a modern reflectorised stop board count as a red signal? On RETB lines they do - and around 12 months ago a fixed yellow distant colour light got replaced by reflectorised board coming off the Ardingly freight branch.

 

 

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On 19/05/2020 at 11:45, phil-b259 said:

 

But doesn't a modern reflectorised stop board count as a red signal? On RETB lines they do - and around 12 months ago a fixed yellow distant colour light got replaced by reflectorised board coming off the Ardingly freight branch.

 

 

Reflectorised distant boards have long been used as 'ordinary' signals or as the 'distant' for colour light signal capable of showing a red aspect - there were a couple on the Oxford - Bletchley line back in the early 1990s.   The situation with STOP boards used to be that they couldn't be used at the end of a running aspect route because they weren't proved in the controls of the signal reading towards them (proved not only as being illuminated but also proved to be there - i.e. they might for some reason have been knocked over or whatever).   Interestingly one oddity I knew of was a semaphore stop signal retained and fixed at danger to allow a main aspect in a colour light signal to be used to take movements onto the line in rear of it; not many of those about I suspect.

 

Operationally while I can see the speed advantage of having a main aspect reading over the connection into, say, a depot, I wouldn't be so keen on the opposite effect of having a train coming into depot territory towards anything other than a fixed red as it's all too easy for things to go wrong and for a Driver to be misled.

 

 

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10 hours ago, The Stationmaster said:

 The situation with STOP boards used to be that they couldn't be used at the end of a running aspect route because they weren't proved in the controls of the signal reading towards them (proved not only as being illuminated but also proved to be there - i.e. they might for some reason have been knocked over or whatever).  

 

 

 

Well given we now have fold down signals on the main line (with nothing to tell the interlocking they are horizontal and thus non visible to drivers), surely a Stop being knocked over is a risk the high ups might well be prepared to tolerate.

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For the situation described by the OP, unlikely as it is, I would not see anything other than a subsidiary as appropriate. The only reason to have a red/yellow signal into the platform would seem to be to provide something to attach the subsidiary to although it does allow for moves on and off depot while a train sits at the platform.

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21 hours ago, phil-b259 said:

 

Well given we now have fold down signals on the main line (with nothing to tell the interlocking they are horizontal and thus non visible to drivers), surely a Stop being knocked over is a risk the high ups might well be prepared to tolerate.

Or not understand?   BTW I think the fold down signals are a triumph of how concern for one area of  safety can lose sight of far wider areas of (operationa) safety and are a great demonstration of how very narrowly targeted use of the risk assessment process can lead up blind alleys.

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21 hours ago, phil-b259 said:

 

Well given we now have fold down signals on the main line (with nothing to tell the interlocking they are horizontal and thus non visible to drivers), surely a Stop being knocked over is a risk the high ups might well be prepared to tolerate.

Why is there nothing? Are we now incapable of producing a reliable position detector for the signal hinge? We manage it for level crossing arms, semaphore signal arms, point machines etc.

 

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13 minutes ago, Grovenor said:

Why is there nothing? Are we now incapable of producing a reliable position detector for the signal hinge? We manage it for level crossing arms, semaphore signal arms, point machines etc.

 

 

Because the powers that be don't think it necessary.

 

In theory (as per the maintenance specs) said fold down signals should only be lowered once a 'complete understanding has been reached with the signaller who will have taken measures to prevent trains approaching it'

 

Granted there are quite a lot of them around now and I am not aware of any signals self lowering / being lowered by staff in error, but as The Stationmaster says, it does go against the grain to have signals which are deliberately designed to 'disappear' these days.

 

All done so that S&T staff don't have to be trained in 'working at height' regulations and be issued with harnesses (or make signals like North sea oil rigs) without which the H&S brigade insist we are going to fall off them

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Some interesting and valid points regarding hinged colour light signals, but......have there actually been many, or any, incidents when an operational signal on a line open for normal traffic has been incorrectly lowered, by accident or on purpose ? And if so, would the Driver's route knowledge not be a safeguard, just as it would with a signal with no aspect illuminated ?

 

(Until my retirement in 2016, the only report I received of hinged signals being lowered was in the Cathcart area of Glasgow, where new signals were being installed but were not yet in use; A suitable item was subsequently added to the WON to explain !)

 

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21 hours ago, phil-b259 said:

 

Because the powers that be don't think it necessary.

 

In theory (as per the maintenance specs) said fold down signals should only be lowered once a 'complete understanding has been reached with the signaller who will have taken measures to prevent trains approaching it'

 

Granted there are quite a lot of them around now and I am not aware of any signals self lowering / being lowered by staff in error, but as The Stationmaster says, it does go against the grain to have signals which are deliberately designed to 'disappear' these days.

 

All done so that S&T staff don't have to be trained in 'working at height' regulations and be issued with harnesses (or make signals like North sea oil rigs) without which the H&S brigade insist we are going to fall off them

Don't get me going on that latter point Phil (where outside the railway there have actually been more personnel accidents on ladders as a result of mods to comply with Working At Height regs than there were before the regs came in - biggest danger being the provision of cages or similar around ladders).  One interesting feature is that as far as I could trace the incidence of railway staff falling off signal ladders and suffering injury as a result was negligible.

 

One interesting point about hinged signals which as far as I know has never been covered is that in the past a signal could only be 'taken away' after a suitable notice entry had been made and published.  But now it has come down to a 'a complete understanding'. (which arrangement has never in the past been found to be foolproof - hence a proper, published, procedure for 'removing' or completely obscuring running signals).

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23 hours ago, caradoc said:

Some interesting and valid points regarding hinged colour light signals, but......have there actually been many, or any, incidents when an operational signal on a line open for normal traffic has been incorrectly lowered, by accident or on purpose ? And if so, would the Driver's route knowledge not be a safeguard, just as it would with a signal with no aspect illuminated ?

 

 

 

During resignalling works (I think on the Leeds Northern) in the 80’s a working signal was incorrectly ‘dropped’ using burning equipment! By all accounts when the fault team arrived it was still lit halfway down the embankment.

   It happened around the time I started as an apprentice and was a standing joke (not in the immediate aftermath) held over the parties concerned for many years!

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On 21/05/2020 at 12:19, caradoc said:

Some interesting and valid points regarding hinged colour light signals, but......have there actually been many, or any, incidents when an operational signal on a line open for normal traffic has been incorrectly lowered, by accident or on purpose ? And if so, would the Driver's route knowledge not be a safeguard, just as it would with a signal with no aspect illuminated ?

Most instances of an unlit signal will be protected by the lamp proving controls, the driver's route knowledge only being needed for unlikely events, such as a nice big bird's nest in front of the lens, or a beehive inside it! Having a proving contact on the signal hinge would be a trivial cost at installation time, so for the powers that be to allow them to be omitted suggests that they anticipate having lots of right side failures to pay compensation for as a result. Hence my questioning said powers' belief in the competence of designers.

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On 21/05/2020 at 11:36, phil-b259 said:

All done so that S&T staff don't have to be trained in 'working at height' regulations and be issued with harnesses (or make signals like North sea oil rigs) without which the H&S brigade insist we are going to fall off them

I don't recollect any significant incidence of staff falling off signal ladders or telegraph poles, I always made sure I didn't!

Probably because those likely to fall didn't take the job.

One of my first tasks on taking up appointment in Adelaide S&T was to interview candidates for the post of lampman at Adelaide station. The interviews took place on the platform end at the foot of a modest height platform starterl. After the introductory pleasantries many candidates were weeded out on the second or third rung unable to get any higher. I did manage to find one possible out of about 7 who turned up.

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Prototypical example here : Central Rivers depot.

 

To enter from the Birmingham end , trains are signalled onto the reception line by a main aspect with junction indicator to a fixed red signal, BD1. This has a position light fitted (and associated route indicator) and trains proceed onto the depot upon clearance of that position light.

 

To enter from the Derby end is the anomaly (and in fairness , very few trains run directly onto the depot this way).

From the Down line , trains are signalled onto the depot by main aspect with junction indication , however in this case the next "signal" is actually a Stop board.

 

To answer the OP's question , the "normal" method for trains to be signalled onto a depot is by shunting signal (either position light or semaphore sub arm/disc) , and in many cases the train will run towards a stop board where the driver will leave it in the hands of the fitters.

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3 hours ago, Grovenor said:

Most instances of an unlit signal will be protected by the lamp proving controls, the driver's route knowledge only being needed for unlikely events, such as a nice big bird's nest in front of the lens, or a beehive inside it! Having a proving contact on the signal hinge would be a trivial cost at installation time, so for the powers that be to allow them to be omitted suggests that they anticipate having lots of right side failures to pay compensation for as a result. Hence my questioning said powers' belief in the competence of designers.

 

Good point, but I'm not convinced that providing a proving contact on every hinged signal would be a trivial cost; How would such a contact being broken be indicated to the Signaller ?

 

When does a hinged signal require to be lowered; Either to repair a fault, which as you said earlier would hold the signal in rear to a more restrictive aspect, or for maintenance, when normal train running would be suspended anyway. Besides, no-one has yet confirmed that a signal being lowered out of course during normal train running has actually happened ! (Of course, I realise I have left myself wide open there........)

 

 

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If you added a 'hinge contact', then what happens if you lower the signal for planned maintenance and then can not check the results of your work 'cos the signal has been disconnected from its interaction with the signal in rear etc? Presumably you would have to re-erect the signal first in order to test?

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I know of one instant that relates to the folding down of a signal is service.

 

 

its wasn’t a full blown spring loaded post, but was a dorman light unit,  that came unclipped inside the signal head and fell over.

 

the lamp was still proved , and alight and  pointing upto the sky, the driver of the train that found simply approached the signal at linespeed Andy found it missing.

 

there has now been a national effort to modify and check all the affected signal to ensure no repeat happens.

 

 

 

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Not so long ago there was a signal at Newbury that fell over due to the base of the post rusting away.  It continued to function normally as far as the interlocking was concerned and the first anyone knew of it was when it was hit by an HST.  Had it happened to fall the other way and not foul of the line then it would have relied on the driver to note its absence and act accordingly.  Same would apply for a fold down signal in the prone position without appropriate authorisation. 

 

Aside from the cost, adding "post upright" proving to such signals might turn out to be more trouble than it's worth in terms of reliability.  What is the likelihood of a signal post being folded down without authority and an accident ensuing?    Must be quite small.  Much bigger potential risks seem to be managed with a procedural element (eg resetting axle counters, TCFs etc) so I'm not sure this is a risk worth mitigating through technology.  However as is always the case with railways, history will be the judge. 

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