Elizabeth Line / Crossrail Updates.

[iands]

"Self cleaning lenses" - just 'salesman' patter, much like "maintenance free batteries" - NO SUCH THING! Everything needs maintaining, and that came from an engineer who had worked for a major battery manufacturing company trying to reverse over a decade of misleading "sales pitch". Okay, I accept some things may need less maintenance these days, but the day you stop maintaining something altogether is the day it all starts to go wrong.

 

I was brought up on the railway with the addage, "if you look after your batteries, your batteries will look after you", i.e. if you keep your batteries in tip-top condition, they will keep your system running when the mains supply fails.

 

Regards, Ian.

Edited April 8, 2018 by iands

[St. Simon]

How do the self cleaning lemses work?

 

During the recent snow the signals at Plymouth were cleaned by an NR bloke with a hand brush because the snow was sticking to the lenses making them almost impossible to see.

The ones at Plymouth are Standard Dormans, not the ILS Fold Down type, the standards don’t have self cleaning lens (or at least not to the same level as the ILS’), hence why they need clearing

 

The ILS’ signals have lens which are angled inwards and downwards (from the front of the hood back to the body) which prevents snow gathering on the lens.

 

Simon

[The Stationmaster]

The specifications I've seen are exactly the same for LEDs as for Filament Lamps.... 

 

 

 

 

Mike, the components that need regular maintenance on the fold down LEDs are all contained within the cupboard at the foot of the signal, meaning regular day to day maintenance of them doesn't require the signals to be folded down. All the lenses are self cleaning so they don't need folding down for that. The only time they require to folded is if the Lamp fails, which in filament terms would mean effective the signal was taken away anyway (although not in physical terms).

 

From what I gather, the maintenance gangs much prefer the LED Fold Downs.

 

Simon

 

Then surely a better solution would be too have everything, including the lamp, in an accessible area which doesn't require the signal to be taken away (in operating terms).  I saw exactly such an approach in everyday use on NS c.20 years ago where fibre optics were the only connection between the lamp etc and the signal head so all maintenance apart from cleaning the lens could be carried out at lineside, and the signals gave a perfectly good light and a completely correct colour.  

 

In operational safety terms if a signal lamp, of any sort, is out, the signal will still be there, even if it is dark and the Rules cater for such a failure; a signal taken away is a very different kettle of fish and goes far beyond normal simple maintenance when trains are still running.  It seems to me that a rather basic feature has been over;looked in that signals are provided to ensure the safe passage of trains and everything else about them has to be subordinate to that rolee.

 

As for the self-cleaning aspect (sorry) I remain to be convinced and snow will stick to just about any surface when temperatures are low enough irrespective of their angle - plenty of past instances of the underside of bridge arches well and truly plastered with snow with no sign of it having drifted to get there, and of course plenty of instances of signal aspects with short or minimal hooding being obscured by snow - including the parts of 'bulls-eye' lenses angled downwards, even with a warm running filament bulb behind them.

[The Stationmaster]

Obviously I don't have to use them in any form, but the principal of the fold over signal is a good one. The vast majority of signal structures is to do with getting a person to the signal head, which when combined with a requirement/ desire to make them accessible without going red zone (adjacent lines being the biggest issue) has resulted in some ridiculous structures. Standing back and questioning why has led to these LED signals which look neat and the support mechanisms are largely in keeping with what they're supporting.

 

Of course if the beam is too small then that wants looking at, and procedures need to be different since the plant is different, but by and large I think they can and will be an improvement.

 

Actually the purpose of railway signals is to help ensure the safety of movements and the safe passage of trains - everything else should be subordinate to that role and not interfere a signal's ability to deliver it.  

 

Really is that simple but seems to be something NR has lost sight of in its fright about people climbing ladders and adoption os some distinctly unsafe things such as caging around some signal ladders when wider industry experience has shown that caging creates more potential risks than it avoids.  Providing platforms at signal heads seems to be a similar example of not thinking things through properly because you lose the advantage of the traditional 'safety ring' against which you can brace your body while working - I was always far happier lamping semaphore arms on gantruy mounted signals when there was a safety ring rather than having to contend with a stupidly sited platform or small landing.

[iands]

Actually the purpose of railway signals is to help ensure the safety of movements and the safe passage of trains ........

I agree with your statement Mike. In one respect, it does seem to be something of a retrograde step, in terms of maintenance, with the introduction of "fold-down" signal posts. The traditional activity of climbing a ladder with a bit of rag and a cleaning agent, leaning around to the front of the signal and cleaning the lenses, was sometimes a bit of an awkward task. But it was achieved within a few minutes and you were constantly aware of where you were and that your safety was in your hands, as it were. The upshot was that the railway kept running (many a time I was up a signal when a train went passed). In order to clean the lens of a fold-down signal, in my mind, requires a possession of the railway (and all that that entails), because as you say, by folding down the signal, you have removed the very item that both signaller and driver are relying on for safe movement of traffic.

 

And when do most maintenance possessions take place nowadays? Yep, at night, when it's dark and you are stumbling around over all sorts of tripping hazards.  Yes you may well have a bright lamp to illuminate a bit of what you are looking at, but IMO there is no substitute for natural daylight when working/walking about the railway - open to traffic or during a possession. Yes, I know lots of engineering works (such as relaying etc.) do, and have to, happen during the night, but these sites are provided with floodlights. I can't see anyone providing floodlights to do normal maintenance.

 

No matter how "well meaning" some of today's 'Health & Safety' views are, they are not all as practical as they first seem. Some of them are viewed in isolation, rather than as a bigger picture.

 

Rant over, I'll get off my soap-box again.

 

Regards, Ian.

[Edwin_m]

I can't see anyone providing floodlights to do normal maintenance.

 Not relevant to signals, but many junctions now have trackside floodlighting permanently installed.  This allows inspection at night when line blocks are easier to obtain. 

[The Stationmaster]

 Not relevant to signals, but many junctions now have trackside floodlighting permanently installed.  This allows inspection at night when line blocks are easier to obtain. 

 

However all such installations I have seen are at low level (presumably for environmental reasons?) which can create serious problems with shadows.  Going from a well lit area into dark shadow is in my experience around the railway at night a darned sight worse than not having to deal with such levels of lighting contrast.  So a good idea but I'm not entirely sure about the way it has been done - but then I haven't had to work under such lighting.  However having had to deal with lamps out on semaphore signals on a dark, and rather wet, winter night I can only say that the patchy spread of light from street lights on the adjacent road overbridge was more of a hindrance than a help

[jim.snowdon]

However all such installations I have seen are at low level (presumably for environmental reasons?) which can create serious problems with shadows.  Going from a well lit area into dark shadow is in my experience around the railway at night a darned sight worse than not having to deal with such levels of lighting contrast.  So a good idea but I'm not entirely sure about the way it has been done - but then I haven't had to work under such lighting.  However having had to deal with lamps out on semaphore signals on a dark, and rather wet, winter night I can only say that the patchy spread of light from street lights on the adjacent road overbridge was more of a hindrance than a help

There were trials carried out of both high and low level lighting before junction lighting was rolled out across the network. They demonstrated the critical difference between the two - with low level lighting, drivers could see signals above any glare cast by the lighting, even in misty conditions. With high level lighting, signals could not be reliably seen through the glare.

 

Jim

[jim.snowdon]

I'm sure that the signal engineers amongst us could provide the answer, but I would expect the state of any fold down signal to be incorporated into the lamp proving circuits such the signal in rear could not show a proceed aspect with the next signal folded down.

 

Jim

[Grovenor]

I think St. Simon has promised an answer to that one when he has had chance to check the diagrams. I would also expect it.

Should be a bunch of Signal Engineers up for re-education if not.

Regards

[Chris116]

Some early railway signals had a ball that was hoisted up to give an off indication and was left out of sight as an on indication! Seems we are possibly going back to the bad old days.

[St. Simon]

Hi.

 

Having just asked the question to my colleagues and discussed it with them, we confirm that there is no proving of the whether a signal has been folded down or not.

 

We concluded that to lower such a signal, it would have to be done under line blockage or possession (admittedly we haven't look at the procedures, I've tried to find them, but I can't, but I could be looking in the wrong place), and therefore those procedures would stop a train being routed up to a lowered signal.

 

We discussed as to why there wasn't any proving and we decided that they only real way of doing it was to provide a Microswitch, but we know that these are extremely unreliable. We thought that the only unauthorised lowering of the signal in reality is through vandalism, but the lowering mechanism is protected by a padlock and the danger of such an incident is no larger than a conventional signal. None of us had heard of a signal self-lowering in service, again the risk is low, and the fact that the signal would fall forwards could mean that there is a chance of it smashing it's own LED's out and causing an alarm. We also thought that the risk of a train passing a signal that had been lowered without authorisation without realising it was as about the same for a conventional signal.

 

Of course, this is our own personal take on the situation, there is almost certainly a perfectly acceptable reason why Dorman didn't provide a proving circuit that we don't know.

 

I know that everyone will now be up in arms about this, but the risk of a signal being lowered without authority, either as a result of a failure or vandalism is very low.

 

Simon

[jamie92208]

Hi.

 

Having just asked the question to my colleagues and discussed it with them, we confirm that there is no proving of the whether a signal has been folded down or not.

 

We concluded that to lower such a signal, it would have to be done under line blockage or possession (admittedly we haven't look at the procedures, I've tried to find them, but I can't, but I could be looking in the wrong place), and therefore those procedures would stop a train being routed up to a lowered signal.

 

We discussed as to why there wasn't any proving and we decided that they only real way of doing it was to provide a Microswitch, but we know that these are extremely unreliable. We thought that the only unauthorised lowering of the signal in reality is through vandalism, but the lowering mechanism is protected by a padlock and the danger of such an incident is no larger than a conventional signal. None of us had heard of a signal self-lowering in service, again the risk is low, and the fact that the signal would fall forwards could mean that there is a chance of it smashing it's own LED's out and causing an alarm. We also thought that the risk of a train passing a signal that had been lowered without authorisation without realising it was as about the same for a conventional signal.

 

Of course, this is our own personal take on the situation, there is almost certainly a perfectly acceptable reason why Dorman didn't provide a proving circuit that we don't know.

 

I know that everyone will now be up in arms about this, but the risk of a signal being lowered without authority, either as a result of a failure or vandalism is very low.

 

Simon

I would have thought that a reed switch such as is used on car doors would be extremely reliable and easy to fit.

 

Jamie

[Edwin_m]

Not a folding one, but there was that signal at Newbury that rusted through at the base and fell across the running line but with all lamps intact and therefore no loss of proving. 

[jim.snowdon]

Simon,

 

An interesting and well thought out response on the part of all concerned. On reflection, it also illustrates the benefit of thinking of the situation in systems terms, not just as a single signal. Where such signals are used, there is a level of system redundancy - in the event of the signal not being there (for any reason), the driver is no longer totally dependent on route knowledge to deduce where a missing signal should be. AWS is more or less universal, so an AWS output with no signal following soon after is a warning. If the missing signal was showing a red aspect, the driver has had forewarning of the fact from the previous signals and is already aimimg to stop at where the missing signal should be. If it was showing a green aspect, there is no issue. The worst case, I think, would be if the missing signal was in two or three aspect territory and showing a yellow aspect, as the next aspect to be seen would the red, but, the driver would still have had a caution indication from the AWS. TPWS will have its place in there as well, but I am not aware of TPWS being fitted to every signal, or precisely what the outcome is if the driver approached a stop aspect at line speed, other than the TPWS initiating an emergency brake application.

Thus, although a signal being irregularly folded down might appear to be a potentially catastrophic event, it is rather less so when taken in context.

 

Jim

[The Stationmaster]

Simon,

 

An interesting and well thought out response on the part of all concerned. On reflection, it also illustrates the benefit of thinking of the situation in systems terms, not just as a single signal. Where such signals are used, there is a level of system redundancy - in the event of the signal not being there (for any reason), the driver is no longer totally dependent on route knowledge to deduce where a missing signal should be. AWS is more or less universal, so an AWS output with no signal following soon after is a warning. If the missing signal was showing a red aspect, the driver has had forewarning of the fact from the previous signals and is already aimimg to stop at where the missing signal should be. If it was showing a green aspect, there is no issue. The worst case, I think, would be if the missing signal was in two or three aspect territory and showing a yellow aspect, as the next aspect to be seen would the red, but, the driver would still have had a caution indication from the AWS. TPWS will have its place in there as well, but I am not aware of TPWS being fitted to every signal, or precisely what the outcome is if the driver approached a stop aspect at line speed, other than the TPWS initiating an emergency brake application.

Thus, although a signal being irregularly folded down might appear to be a potentially catastrophic event, it is rather less so when taken in context.

 

Jim

 

Agree absolutely but it does also make a difference if a Driver is using the signal as a visible mark as well as an audible one (don't forget - AWS is only 'an aid'.   What Simon has said is of course entirely logical to my mind - and that in my view is part of the problem, if one of those signals needs attention and has to be lowered you have to shut the railway and that strikes me as as excessive for what inevitably could only be something minor (or snow on obscuring the aspect).  That might explain why Simon can't find a procedure - maybe one doesn't exist - and as yet I have been unable to find anything in the Rule Book (mind you that just as much be a fault of the way the Rule Book seems to be intent on ignoring commonsense and being easy to follow, bring back Section E!)

[St. Simon]

Agree absolutely but it does also make a difference if a Driver is using the signal as a visible mark as well as an audible one (don't forget - AWS is only 'an aid'. What Simon has said is of course entirely logical to my mind - and that in my view is part of the problem, if one of those signals needs attention and has to be lowered you have to shut the railway and that strikes me as as excessive for what inevitably could only be something minor (or snow on obscuring the aspect). That might explain why Simon can't find a procedure - maybe one doesn't exist - and as yet I have been unable to find anything in the Rule Book (mind you that just as much be a fault of the way the Rule Book seems to be intent on ignoring commonsense and being easy to follow, bring back Section E!)

Hi Mike,

 

There is a procedure, I just can’t find it as I’m not maintenance, and I don’t know where to look precisely!

 

Simon

[Zomboid]

There's also the consideration that these things are (supposed to be) massively cheaper to build, and you have a much smaller liability in terms of the structure which has to be maintained for the life of the equipment. If these new signals need significantly less attention than the older style ones, cost less to build and present a smaller ongoing liability, then the negative consequences of them need to be weighed up against that.

The answer to that will vary for each site, but every decision has consequences. And remember that this modular signalling business was invented to save money whilst not presenting unacceptable compromises.

[St. Simon]

Hi,

 

I just managed to have a chat with some maintenance colleagues, the procedure for lowering a signal is just to liaise with the signaller to ensure that no trains are approaching, no blockage necessary.

 

Simon

[phil-b259]

Hi Mike,

 

There is a procedure, I just can’t find it as I’m not maintenance, and I don’t know where to look precisely!

 

Simon

 

If its a maintenance angle you are after then I suggest you search in 'Connect' for the electronic SMS (Signal Maintenance Specifications*) which should provide you with the information you need.

 

* For the benifit of others, The SMS was introduced after the Clapham Junction crash in 1987 when it emerged that there weren't any national issued instructions as to how a signalling technician should be maintaining or testing (the latter being the relevant issue at Clapham). The full suite of documents are now produced online for all NR techs to download to their i-devices so they may be consulted in the field.

 

SMS - Which lays on in specific and explicit details exactly what checks and tasks must be done on any individual item of signalling equipment. Any S&T tech can use the SMS to help them undertake maintenance tasks, but the maintenance can only be 'signed off' as completed if the tech is competent (by way of being specifically trained) on that piece of equipment (e.g. HW style point machines)

 

SMTH (Signalling Maintenance Testing Handbook) - which lays down the exact tests and checks to be done after replacing components / wiring  - both under maintenance where a component needs replacing due to wear say, and during failure investigation / rectification. It ONLY covers like for like replacement and must NEVER be used for the installation of new equipment. SMTH testers require to be sent on a dedicated course before they may undertake any SMTH testing (though any S&T tech can assist said tester in performing the tests where instructed). First line S&T response will be by SMTH trained staff.

 

SWTH (Signalling Works testing Handbook) - This governs the checks and tests to be undertaken during the installation of NEW (and that includes remodelled) signalling equipment. This would include those responsible for installing and testing the designs Simon and the design office have produced as they are installed. SWTH testers also have to undergo significant training before they are permitted to undertake the role of SWTH tester - and as 'new works' can range from the minor to major, SWTH testers tend to specialise in certain areas rather be expected to test everything.

Edited April 9, 2018 by phil-b259

[phil-b259]

Hi,

 

I just managed to have a chat with some maintenance colleagues, the procedure for lowering a signal is just to liaise with the signaller to ensure that no trains are approaching, no blockage necessary.

 

Simon

 

So no different to any other daytime activity (track circuit or point testing for example)

[jim.snowdon]

Hi,

 

I just managed to have a chat with some maintenance colleagues, the procedure for lowering a signal is just to liaise with the signaller to ensure that no trains are approaching, no blockage necessary.

 

Simon

Which, if I recall correctly, is very much the same procedure as applies when checking/replacing bulbs on traditional colour light signals.

 

Jim

[phil-b259]

Which, if I recall correctly, is very much the same procedure as applies when checking/replacing bulbs on traditional colour light signals.

 

Jim

 

True - but when working on a filament lamp fitted signal the actual structure is still there!  OK at night a 'black' signal may not be identifiable as such but certainly during the day the physical form is still recognisable from a good distance.

 

As such if a mistake in communications ends up with the techs working on a different signal to that which the signaller thinks they are, then I would suggest that a train approaching a 'black' (or 'all aspects' if the tech has the back open during they day) is probably preferable to not having a signal at all.

 

As with many things on the railway, if enough holes line up, the seemingly impossible can happen so while theoretically observance of rules mean fold down signals present no increased risk over fixed posts, that doesn't necessarily mean there are not increased risks per say.

 

Its a bit like track circuits - they are only officially there to detect the absence of trains and their replacement by thus axle counters is fine. However the fact that track circuits also might detect broken rails in certain circumstances (please note the use of the word 'might' - plenty of track circuits have continued to work even with a broken rail over the years) or other metallic obstructions is however a useful side benefit which provides that little bit of 'extra' protection as it were. A proper signal post with its ID plate easily visible to the driver thus offers that little bit of extra reassurance over fold down signals as it were - even if its not displaying any / the proper aspect.

[Ron Ron Ron]

[Joseph_Pestell]

Rant over, I'll get off my soap-box again.

 

 

 

I trust that you undertook a full risk assessment before climbing onto such a dangerous structure as a soap box. Does it meet all current standards in relation to protection from accidental falls?