Signal boxes

[iands]

Interesting 'proposal'. The 'heritage' issue might not be too much of a problem (but obviously it might be a subjective/emotional issue to some depending on the actual heritage railway concerned), but there were many power-worked points (be they electric, electro-pneumatic, electro-dynamic, etc.) in use during the steam era, in fact, some power-worked point installations were older than some steam engines - particularly the "BR Standards".

[RailWest]

You are right of course about 'power working' having its own historical value, but I'm not sure how the idea will go down well with those with an interest in the line concerned. My point was more about the (possibly flawed) rationale behind the proposal, given that many other heritage railways seem to manage quite well with (largely) mechanical operation, even if there are occasional instances of power points/signals for specific reasons.

[Mike Storey]

Very tricky but some compromise is likely to be necessary over coming years, especially on those preserved lines with very low numbers of volunteers for the S&T department. Wear and tear is not likely to be excessive (other than perhaps for those roads exiting the sheds) but eventually replacements are needed - where do you get them these days other than pre-used parts from the big railway? I know there are one or two specialist engineering firms who can supply certain items off-the-shelf (such as roller bearings, angle cranks and so on), and custom make others, but these are not cheap by any means - my only experience of this in recent years is on a narrow gauge railway, where major track re-modelling has and continues to take place over a number of years, and we only have one signal box. But a proposal to construct a second one at the other end of the line turned out to be more expensive than building a new loco!

 

So, we are building a new loco.

 

 

 

[The Stationmaster]

Yesterday I had quite a long chat about this with a signal engineer and some interesting points emerged.  Apparently NR have some sort of equipment (a strain gauge was mentioned but detail not known) for measuring the load involved in pulling a lever in a signal box although neither of us could understand how this would be done on certain types of locking frame where no properly trained or competent Signalman ('ler' for the modern types) would actually use a pulling force to move the lever.

 

There seems to be more than a suggestion within NR where the approach has arise from people without practical experience of operating a signal box lever frame, an opinion reinforced in some respects by the rather peculiar 'safe' method of working levers shown in an NR publication which used an REC frame as the example of 'how to do it properly.  It seems that publication has had even wider circulation than I'd previously heard about.

 

However one real problem which has definitely emerged is the replacement of older point work with modern flat bottom switches especially near the 350yd limit for manual working because they are much heavier and stiffer than the switches they have replaced and the inevitable answer is to convert such points to power operation, which makes considerable sense of course.  Rather less sensible in engineering terms are proposals to fit point machines to older switches where nonstandard applications and parts are likely to be involved but it is being stated as 'the way to do it because power operation is the way forward'.

 

As ever, so I was told, there are differences in maintenance levels which inevitably mean some points are harder to work than equivalents located in an area where maintenance is to a higher standard.

[phil-b259]

On 10/05/2019 at 15:24, The Stationmaster said:

Apparently NR have some sort of equipment (a strain gauge was mentioned but detail not known) for measuring the load involved in pulling a lever in a signal box although neither of us could understand how this would be done on certain types of locking frame where no properly trained or competent Signalman ('ler' for the modern types) would actually use a pulling force to move the lever.

 

Page 16 onwards of the NR document (appendix A) shows the approved strain gauge fitted to a number of different lever frame designs (including the REC type). As can be seen the signaller pulls on the dummy handle and a strain gauge built into the device tells you how much force is needed to pull that lever.

 

Obviously it cannot give guidance to technique which has an impact ( just as when lifting stuff and manual handling courses talk about using your leg muscles to do the work and not your back) - but as far as actual pull / push forces are concerned its all very straightforward to determine values.

Edited May 11, 2019 by phil-b259

[phil-b259]

On 10/05/2019 at 15:24, The Stationmaster said:

Rather less sensible in engineering terms are proposals to fit point machines to older switches where nonstandard applications and parts are likely to be involved but it is being stated as 'the way to do it because power operation is the way forward'.

 

 

They would have to be pretty odd set of switches to not be able to employ a HW1000 / HW2000 points machine which is fully compatible with pretty much every time of rail used thus far.

 

Similarly given how long they have been around, traditional clamp lock points (i.e. not the in barer ones) include a full set of tooling (to use a model railway theme) that can accommodate bullhead stock & switches if necessary.

[The Stationmaster]

On 11/05/2019 at 19:07, phil-b259 said:

 

Page 16 onwards of the NR document (appendix A) shows the approved strain gauge fitted to a number of different lever frame designs (including the REC type). As can be seen the signaller pulls on the dummy handle and a strain gauge built into the device tells you how much force is needed to pull that lever.

 

Obviously it cannot give guidance to technique which has an impact ( just as when lifting stuff and manual handling courses talk about using your leg muscles to do the work and not your back) - but as far as actual pull / push forces are concerned its all very straightforward to determine values.

But if I'm reading it correctly all of them start the measurement with the lever partially reversed and as any competent experienced Signalman will tell you the last thing you do when pulling a lever is stop with it part stroke and then start pulling again.  That's a good way to injure yourself as you're not pulling the lever in the most efficient way and you aren't making best use of the impetus of your body weight.  

 

Amusing to see an example where it is used on a lever operating a power worked function but probably easier to demonstarte for a photo on a shortenred lever handle.

[Chime Whistle Books]

On 04/05/2019 at 21:36, phil-b259 said:

 

A very important thing for those with rose tinted spectacles to note!

 

In the 'olden days' the railway (and other heavy industries) were very good at killing or maiming their workforce - and a slipped disc or Hernia is ever bit as much of an injury as a broken leg.

 

The best way of avoiding harm from an accident is to net let it happen in the first place - PPE or other similar things (like non slip surfaces) should only be considered if it is impractical to do away with the risk in the first place.

 

For over a centenary, we have had the scientific know-how to move lumps of rail (points) about or a piece of steel sheet (i.e. a signal arm) without the need for manual effort by employing hydraulic, pneumatic or electrical devices - the problem in the past has been the existence of cheap / expendable labour meaning the economics didn't always make it viable.

 

These days, a good business will seek to minimise the numbers of staff they employ - AND crucially try to ensure those they do employ are not continually going sick with things like bad backs.

 

So while existing mechanically signalled areas can remain (assuming it is in tip top condition), whenever the opportunity arises its good practice to improve the situation. This can be as simple as motorising all points (which has been undertaken at Bognor Regis during the last decade) for installing colour light signals, thus turning the levers into big switches with no force required to operate them.

 

Equally while it may not be viable to upgrade existing siding installations - if putting in a new facility or heavily rebuilding an existing one then putting in powered equipment should be the first choice.

 

 

A distant at Hednesford was motorised when a new,lady, signaller was appointed resident and had difficulty pulling it fully off. The box was due for closure,now closed, at that time, so presume this was the most cost effective option compared to installing a colour light distant. A signaller ended up under the desk at Bloxwich when lever 27 snapped as he was pulling off.That's something one just cannot account for when setting a route!

 

Access to Tyseley depot is controlled by Tyseley No.1, a box with no track circuits, and a very busy box on the night shift. Latest estimate for its replacement is 2047!

[bécasse]

3 minutes ago, Chime Whistle Books said:

A distant at Hednesford was motorised when a new,lady, signaller was appointed resident and had difficulty pulling it fully off.

Rather more than fifty years ago I was on an official visit to Andover Junction A box and the bobby invited me to pull off the down distant. Andover Junction was at the foot of a bank, so not only was the distant a long way off but the pull was uphill. I pulled the lever which, as I had anticipated,  was quite a hard, but not stiff, pull, then I looked up at the repeater which was showing "WRONG". Have another go said the bobby, three tries later, the repeater still said "WRONG". That's funny, said the bobby, none of us can get it to go to "OFF" either and the lineman can only get it to show "ON" and "WRONG" or "WRONG" and "OFF" so obviously the former is preferable. 

[Chime Whistle Books]

6 minutes ago, bécasse said:

Rather more than fifty years ago I was on an official visit to Andover Junction A box and the bobby invited me to pull off the down distant. Andover Junction was at the foot of a bank, so not only was the distant a long way off but the pull was uphill. I pulled the lever which, as I had anticipated,  was quite a hard, but not stiff, pull, then I looked up at the repeater which was showing "WRONG". Have another go said the bobby, three tries later, the repeater still said "WRONG". That's funny, said the bobby, none of us can get it to go to "OFF" either and the lineman can only get it to show "ON" and "WRONG" or "WRONG" and "OFF" so obviously the former is preferable. 

Stafford No.4 had a handful of manual point levers,relating to the nearby sidings, which could be difficult to reverse. Not helped by the fact that the sidings were only used once in a blue moon!

[St Enodoc]

On 13/05/2019 at 06:29, The Stationmaster said:

But if I'm reading it correctly all of them start the measurement with the lever partially reversed and as any competent experienced Signalman will tell you the last thing you do when pulling a lever is stop with it part stroke and then start pulling again.  That's a good way to injure yourself as you're not pulling the lever in the most efficient way and you aren't making best use of the impetus of your body weight.  

 

Amusing to see an example where it is used on a lever operating a power worked function but probably easier to demonstarte for a photo on a shortenred lever handle.

Sometimes you had to do exactly that, especially with a long pull, to make sure the points threw properly. The points at the north end of Horsted Keynes (no 3 I think) and the long crossover at the south end (19) in pre-through station days were like that. Even then, it wasn't unknown for the fireman to get down and give them a good kick to get them to fit up and get the detection.

[rogerzilla]

The new signalling building at Didcot Railway Centre might be worth a visit.  They have stuff from various eras, including the whole 1960s Swindon power signalling panel for the GWML, wired up and working (with simulated trains).

[Edwin_m]

On ‎04‎/‎05‎/‎2019 at 20:30, brianusa said:

But thanks for all the replies which certainly provide an insight into modern railway practices in the UK these days.

Power signalling in the UK actually owes a lot to the Centralised Traffic Control schemes in the USA, which pioneered power operation and remote control techniques.  The operating principles are different but a lot of the technology was imported. 

[Mike Storey]

34 minutes ago, Edwin_m said:

Power signalling in the UK actually owes a lot to the Centralised Traffic Control schemes in the USA, which pioneered power operation and remote control techniques.  The operating principles are different but a lot of the technology was imported. 

 

I am no expert by any means, but I believe I have read a number of explanations which suggest that was marginal. Primarily, CTC was developed in the USA to resolve the problem of the safety and efficiency of bi-directional single line operation, by far the major aspect of US operations, and reduce the costs of doing so. That was not what it was primarily developed for in the UK. Perhaps the greatest US contribution was the later, three-processor logic applied to electronic interlocking, as introduced by Westinghouse. But even this was differently applied - the main use in the USA was to enable remote interlockings, reacting to routing request by a centralised controller. UK railways kept interlockings centralised with power boxes until much more recently. CTC in the UK for decades, in terms of the more efficient use of track space, was the original ARS, with its variable utility in times of peturbation (when many signallers would turn it off), but has more recently become more like the US aspiration, but far more complex.

 

No doubt our signalling experts on here will have more definitive opinions. But there were certainly lessons to be learned from US operations, I agree.

 

[Edwin_m]

8 hours ago, Mike Storey said:

 

I am no expert by any means, but I believe I have read a number of explanations which suggest that was marginal. Primarily, CTC was developed in the USA to resolve the problem of the safety and efficiency of bi-directional single line operation, by far the major aspect of US operations, and reduce the costs of doing so. That was not what it was primarily developed for in the UK. Perhaps the greatest US contribution was the later, three-processor logic applied to electronic interlocking, as introduced by Westinghouse. But even this was differently applied - the main use in the USA was to enable remote interlockings, reacting to routing request by a centralised controller. UK railways kept interlockings centralised with power boxes until much more recently. CTC in the UK for decades, in terms of the more efficient use of track space, was the original ARS, with its variable utility in times of peturbation (when many signallers would turn it off), but has more recently become more like the US aspiration, but far more complex.

 

No doubt our signalling experts on here will have more definitive opinions. But there were certainly lessons to be learned from US operations, I agree.

 

I was referring to the technology not the operating principles.  Remote interlockings operated by non-vital TDM links came from the States I believe.  It was indeed used on the long single lines where it would have been costly and difficult to provide a person at every loop and with the low frequency of large trains those people would have had little to do.  But the UK adopted a very similar architecture for much denser railways from the 1960s onwards.  Nearly all power boxes had the interlocking for more distant areas in remote relay rooms, the main exceptions being Trent and Saltley.  Some of those remote relay rooms have been re-controlled and operation centralised by newer control centre systems. 

 

As far as I'm aware three-processsor interlocking started with SSI, invented by some of my former colleagues (and sold by GEC and Westinghouse) and definitely British.  Traditional SSI had centralised interlockings but various other configurations have been used more recently with SSI or the more recent computer based interlockings, often due to partial replacement where for example the interlocking is life-expired but the trackside equipment is still serviceable. 

[The Stationmaster]

11 hours ago, Edwin_m said:

Power signalling in the UK actually owes a lot to the Centralised Traffic Control schemes in the USA, which pioneered power operation and remote control techniques.  The operating principles are different but a lot of the technology was imported. 

Quite true that some early UK power signalling used imported kit from the USA (provided that , unlike one 'lever frame', it didn't get sunk by a U Boat when crossing the Atlantic during WWI).  But indigenous equipment seems to have appeared fairly early on as well, particularly on the London underground lines.   I'm not sure but I have long been under the impression - partly because it was not a US design but came from Siemens' British arm - that not only was quite a lot of pre-WWI power signalling kit not of US origin but also that the GWR's route lever installations were not of US origin either and the first in fact pre-dated CTC by several years.  And the next step forward from route lever interlockings was to OCS type panels (not that the GWR ever had any of course)

 

The NX panel system of operation was definitely of US origin (being  first used on a model railway before progressing to the real world) although the first British installation wasn't very far behind but  used some US supplied equipment and presumably the panel itself came from GRS who were pushing NX in Britain at that time. 

[Merfyn Jones]

Back to the original theme. Many preserved lines may find difficulty getting people with the skills to set up mechanical points and signals. 

I retired as a lineman 9 years ago and am now 70. There was not much training on mechanical stuff before I finished and by now probably even less. So the preserved lines are probably suffering the same in signalling as in other skills,  an ageing workforce.