Signal heads

from what i have seen and heard about LED's in signal heads on LUL it will be only allowed if the LED's was a direct replacement for a bulb (like the type in plat repeaters)
the ones you are referring too are very big and have lots of ultra bright LED's and there is concern about them being too bright especially down the tunnels plus for us it will be the end to the nice easy relamp jobs we get

I don't suppose there is much call for LED replacement bulbs on the DR as most of your signals are outside and to be honest I'm not sure whether LU has replacements for the bulbs in LRCL signals yet. On the Picc we changed all the bulbs for LED clusters in the tunnel signal heads and repeaters years ago. In fact I think the Picc led the way in this field and we tried several types of LED cluster before settling for one with the correct sighting and illumination properties.
As for relamping, yes much 'work' was lost following the LED replacement programme. Strangely at the west end of the Picc relamp jobs almost always occurred following night signal maintenance by one particular lineman. We discovered that rather than arrange to display aspects to check the bulbs he simply swapped a working bulb from the displayed aspect to the extinguished one and then tested the displaced bulbs in the displayed aspect, changing them if necessary! Obviously disturbing working bulbs in this way weakened them but his laziness was frequently rewarded at 0630 as he was preparing to ready himself for home as he had to take the calls!

My habit was to clear and replace or vice versa all signals when doing maintenance or at least arrange for all controlled signals to be cleared in advance from the control room in areas such as Heathrow
where I couldn't be in the loop and at the frame simultaneously. It was handy having an auto in the tunnel at 10s points as invariably someone (usually the Pway) would have earthed the track(s) and replaced a signal before I reached them! I suppose such communication would be much easier now that Connect has gone live.

Brian

Taking all the above into account;

As I have stated elsewhere in this thread LU already has LED clusters in tunnel signals. The resighting work was minimal as I recall except for one location which was the W/B starter at Hatton Cross due mostly I believe to the platform lighting which lead to a further development of LED cluster. AFAIK LED tunnel signals have been operating quite successfully for almost 5 years now.

I see no reason why a NR type searchlight signal could not be developed to replace LUs LRCLs and SRCLs using LED clusters, after all the basic signal has been in existence for many years and I would expect all the real design work to be directed at the base of the signal post where the LED clusters and beam focussing equipment would be mounted.

Approach controlled signalling, suppressed repeaters and indeed suppressed danger aspects are all tried and tested fetures of LU signalling and I can't see any specific reason to change what exists to accommodate LED cluster technology.

As for sighting, it is a task like many others in railway work and I would not expect every signal to need to be resighted unless it was changed in which case it would have to be resighted anyway so that is a null point.

Brian

Brian

This is simply ridiculous, it is impossible to properly maintain signal assets without operating them. Staff working on or about the track are required to be competent, licensed and properly protected by a competent and licensed Protection master familiar with the area in which work is being undertaken. Under the rules no-one should be working around points unless they are clipped and scotched or unless they are being maintained by properly licensed staff.
One of the fundamental flaws in the coordination of engineering works (SABRE) is that the people who 'coordinate' the work generally have no idea about how one task will or may impact upon another. As a lineman doing night maintenance I was either in charge of an area that I was maintaining or I was not but I would never sign check certificates for signalling that I was unable to test fully. Quite honestly anyone who signs a safety AWC these days without having performed ALL the necessary checks and tests to ensure compliance with signal standards is cavalier to say the least.

It was also my habit to reserve enough time for a full frame test which is a major undertaking at sites like Wembley Park, Arnos Grove and Northfields and almost as bad if having to fully test Acton East and West.


On the Connect point I was not thinking about the signal operator at all. In engineering hours the control room was mine if I was the appointed lineman so long as there were no outstanding operating tasks i.e. Train Masters and Possession Masters needing to talk to the signal operator. As a maintenance lineman I would contact my colleague in the control room to clear signals on site for me not the signal operator and similarly when I was in the control room I cleared routes, set up TDs etc for colleagues doing signal maintenance. I also worked the line Controllers TT panel under the prevailing rules and regulations liaising with colleagues testing those assets.
In the days before PA, CCTV and Train Radio maintenance was outsourced I would also work on those control room assets liaising as necessary with outside staff observing the necessary restrictions i.e. Noise Abatement.
My point regarding comms was rather about liaising with the control room TO.

Brian

the type i was referring to are already being tested and waiting approval for main use are working on the w/b approaching south ken these are all at different hights and so far have not had any objections yet

Reading all the replies very interesting, but where do LU have LED signals I believe on SSL there are some and on the Central line there is fibre optics but no LED? Reading the reports there still seem to be a large number of spads due to no aspect and the poor T/Op glides past or makes every effort to stop when they have relised they should be stopping due to a danger signal.

As I mentioned the Picc has them in the tunnels, LED clusters in standard 4.5" tube signal heads.

Brian

ISTR the Picc leading things as well. Pity the final product chosen was non-compliant with a Cat 1 LU standard. ;D



I know the Jubilee line had a number of problems - some of which were phantom aspects caused by the relationship between the headlights and the signal, and some because the LED cluster had a narrower beam compared to a lamp, which led to reports of dim aspects.

EDIT: Oh, and I forgot to mention that any changes to the sighting of a signal should be subjected to a principles test as per LU Standards.



I think you mean Marl, who are the manufacturer. No complicated abbreviations this time!

Yep Marl rings a bell with me!

Now what makes you think the LEDs fitted to the Picc tube signal heads were not compliant with signal standards? I hope you don't think we just picked a replacement off the shelf and used it. It was months and months of evaluation, testing and redevelopment as I recall.

Just which LU Cat 1 standard might you be referring to?

Now just who do you think sights the signals in the first place and do bear in mind that there is a deal of difference between sighting and siting with standards applicable to both and the scale plan too of course!

Naturally where siting or sighting is an issue a suitably qualified and appropriately licensed individual will authorise the alterations and a suitably qualified and appropriately licensed individual will make the alterations under a safety AWC.

My recollection is that initially LED clusters were trialled at certain signals under an AWC, subsequently following approval LED clusters were simply fitted as replacements as normal routine maintenance.

Actually it was the Picc that led the way in changing track circuit fuses as well. Now we ditched nearly all the glass 3 Amp track fuses in favour of Bussman ceramic fuses in an attempt to kill two birds with one stone. Glass fuses are deemed to be a H&S hazard and they seemed to fail easily. Unfortunately after we had changed a great deal of track fuses we discovered that not only had the new fuses not been approved but also that they had an inherent flaw and were less reliable, often fracturing during installation or removal. Track failures actually increased as a result. We then hurriedly ran around like headless chickens replacing all the Bussman fuses with an approved ceramic type, this being the Ferraz fuse. The replacement program meant fitting 2 Amp ceramic fuses instead of 3 Amp and 4 Amp ceramics instead of 5 Amp.

This was all occurring at a time when we were changing every trainstop motor for a new much lighter aluminium type and also changing all the point motors and chairlock WLs too. It was a very busy period as I recall.

I am surprised at that because I asked the very question regarding redundancy when we were installing the LED clusters and fitting a dummy cap in the standby lampholder. I was told that the LED clusters comprised parallel LED circuits!