Potters Bar accident caused by points failure

[Bedpan]

cameras are generally sign posted and painted yellow after all.

Yes but how often do you have to slow down when you see a camera because you are only 95% sure that you are driving within the speed limit, and so stand a 5% chance of getting a ticket if you happen to be mistaken. I think that they should have speed limit repeater signs on or within sight of all cameras.

 

[jon0844]

In Sweden, where limits are being both decreased AND increased (including a 10kph increase that they've never had before on motorways - which says in itself that speed isn't automatically dangerous), they seem to have removed loads of speed limit signs. As a result, I was unsure at times what it was - had I missed a sign? - and there was no reminder even by a camera. I relied on my TomTom which showed the limit, but even that wasn't always right (because, as I said, they're changing them).

We actually seem to have no shortage of signs here, and repeaters, so there's little excuse not to know the speed. Why we don't have lower speed limits in bad weather, or even minimum speed limits per lane (as on some stretches of the German autobahns) really confuses me. The first is common sense, but the second actually discourages the person that drives at 50mph in lane two and says 'the speed limit is a limit not a target' and then makes people have to overtake in lane 3, encourages road rage and.. well.. you get the idea, hence why they seem to have sussed out how to give you some freedom, while also laying down firm and fair rules.

Anyway, back to trains, and the money for safety seems to be on equipment that makes something safer. As I said, it's not the same on the roads. What we'd be talking about is not a camera but something in the vehicle itself to stop a collision or speeding. And that would not only be unpopular (as people who drive would think they are in full control, unlike when on a train under the control of someone they can't see) but incredibly expensive. Technology will no doubt allow cars to be tracked and know their surroundings, which could avoid or reduce collisions. That technology is here now, and will be refined and made cheaper.

The other consideration is this; a train driver (or airline pilot) is a professional and unlikely to be drunk, not licensed and so on. That's something that really sets roads and trains apart. That's also why I'd prefer to pay for more police to find these people and get them off the streets.

 

[LE Greys]

But the "national speed limit" is not the same for all vehicles, for a car it is a simple 60 or 70, but for a 44 tonne artic it is 40, 50 or 56? and coaches 50, 60 or 70?
If you replace the GLF with proper speed boards then the new speed would apply to all vehicles which would not be correct, which is why we use the GLF.

The European (or at least the Austrian) version uses a greyed-out version of the NSL sign, with the speed limit visible behind the grey in black. That could be an acceptable compromise.

 

[jon0844]

That merely shows the end of that speed limit, and isn't really necessary (do you need to know what the limit was behind you?).

What you do see are signs saying what the speed limits are for certain vehicle types at the borders, as well as limits for certain road types. You'll pass them quickly and may well miss them, or forget, especially if you're driving through France, Belgium, Holland, Germany, Denmark etc.

 

[Sapphire Blue]

It would help if they painted the speed limit on the back of the cameras using one of those 6-inch (ish) repeater type cirlce signs. The fact that other vehicles than cars have different speed limits is irrelevant as its the speed that triggers the camera.

 

[jon0844]

Another nonsense of the cameras, given some vehicles won't trigger a camera even when they're speeding and potentially far more dangerous - from a heavy lorry to caravan.

 

[keefysher]

Another nonsense of the cameras, given some vehicles won't trigger a camera even when they're speeding and potentially far more dangerous - from a heavy lorry to caravan.

Or towing a trailer with a speeding van in the outside lane of a motorway!!!
--- old post above --- --- new post below ---
Newbie here, but not to rail.

Re Potters Bar. Same staff in place as under BR, 2 IMC's and NR. Was the resistance to commercial business a factor?

TPWS - is it the saviour for trains at 125 mph? Or does it only work below 85?

If Bob Crowe and his intellectually challenged mates truly want track worker safety, why has OTMWIS not been implemented since it was approved in 2003. How many other workers other than at Reading been killed for possession provision? NR, ORR, HSE, RSSB & RAIB all have responsibility.

On speed cameras. A world renown expert of chemical effects of the human motor system lives in Swindon. His work shows that medication and additives to food slows us down in terms of reactions. Further, research shows accidents at speed cameras increase due to the wave effect, the further back in the line the more chance of rear end shunts.

The elf & safety culture in the UK has produced industries within industries and made lawyers rich; but not actually prevented fatalities.

On the media and BP. Why no mention in the media of the oil slick in the Niger delta caused by US oil companies. Tony Hayward was correct, Deepwater Horizon was a **** in the ocean. The US government have today confirmed the level of pollution is very low!!

I'll be asking some techie questions soon.

Choo choo

 

[Peter Mugridge]

TPWS - is it the saviour for trains at 125 mph? Or does it only work below 85?

An important point to consider is that while it will stop a train from 85mph ( I had thought it was 70mph though?? ) in time to avoid an accident, it will also reduce the impact speed, and therefore the severity of an accident, considerably for a train that is faster than that speed.

 

[keefysher]

An important point to consider is that while it will stop a train from 85mph ( I had thought it was 70mph though?? ) in time to avoid an accident, it will also reduce the impact speed, and therefore the severity of an accident, considerably for a train that is faster than that speed.

Unfortunately, an unrestrained body of say 15stone, travelling at 55mph or 40mph inside a train carriage; as would be the case in an impact, of a TPWS stopped 125mph train, doesn't stand much chance of survival. Also need to consider full braking force from 125 down to 55 exerted prior to impact.


Vehicles et all may be able to better endure collisions nowadays, but the human hasn't been made differently for millions of years!!


It's the sudden stop that causes the human internals to react badly

 

[Old Timer]

An important point to consider is that while it will stop a train from 85mph ( I had thought it was 70mph though?? ) in time to avoid an accident, it will also reduce the impact speed, and therefore the severity of an accident, considerably for a train that is faster than that speed.

I think it needs to be remembered that only a very tiny percentage of SPADs ever run outside of the overlap, and that in the very vast majority of those cases, the Driver already has control of the train anyway.

Without wishing to be too controversial, as far as I am concerned TPWS has been a massive waste of money.

TPWS-ophiles would have us believe that the equipment is intervening and bring trains running at high speed through signals at Red to a stand before they hit another train. In fact for the reasons stated above, SPADs very very rarely involve trains running at high speed.

Taken over the lifetime of TPWS, it is calculated that statistically it will kill more people than it will save, but then I suppose the TPWS-ophiles feel that maintenance and installation staff's fatalities are an acceptable outcome.

The last time I did some work related to this, no-one could actually point to a situation where TPWS could be shown of itself to have prevented any fatalities as an outcome of a collision.

TPWS was just a recent manifestation of safety by proxy in which the Media, the public and various other uninformed people have brought about an interference with Railway safety without any real long term benefit.

The money that has been wasted om TPWS can only be justified by people making tenuous claims about lives saved. The fact is that statistically Ladbroke Grove HAD to happen, and having happened is unlikely to occur again for some considerable time.

Meanwhile, whilst we spent £ms on TPWS, other far more worthy and productive options were denied through lack of funding. Like for example replacing a variety of Interlockings where the wiring insulation is so bad that every efort is made to avoid going near it, and if a problem occurs, even a simple repair can and does damage other wires with a dominoe-style effect.

When we take into account the various equipment failures caused by TPWS, and the need for rolling stock to be faulted as well, the costs mount up.

Unfortunately whilst ever safety becomes emotionalised by Media commentators, avaricious ambulance chasing lawyers, prehensile relatives, and Politicians with an eye for personal publicity and a quick soundbite, REAL safety improvements will never be able to occur.

Sometimes the best solution to a problem is to do nothing at all. Unfortunately we have lost the ability to manage our Railways now and simply just knee-jerk to the "demands" of an ignorant public/press/media who are unable or unwilling to understand the bigger picture.

 

[Aictos]

As opposed to TPWS or TPWS+, what is ATP like? Is it a superior system?

 

[ainsworth74]

If you have a spare 20 minutes there is quite a good video here that acts as an introduction to the system.

 

[GB]

Taken over the lifetime of TPWS, it is calculated that statistically it will kill more people than it will save, but then I suppose the TPWS-ophiles feel that maintenance and installation staff's fatalities are an acceptable outcome

How many people have been killed as a result of TPWS installations?

Are you seriously suggesting that without TPWS (or similar) the railway would be a safer place?...mighty words if you can back it up!

 

[Old Timer]

How many people have been killed as a result of TPWS installations?

Are you seriously suggesting that without TPWS (or similar) the railway would be a safer place?...mighty words if you can back it up!

If you go to the RSSB site you should still be able to read the study carried out that reached that conclusion.

You tell me how many fatalities have been averted by TPWS intervention ?

Again read the research report and look at the SPAD reports.

 

[nedchester]

Unfortunately whilst ever safety becomes emotionalised by Media commentators, avaricious ambulance chasing lawyers, prehensile relatives, and Politicians with an eye for personal publicity and a quick soundbite, REAL safety improvements will never be able to occur.

Sometimes the best solution to a problem is to do nothing at all. Unfortunately we have lost the ability to manage our Railways now and simply just knee-jerk to the "demands" of an ignorant public/press/media who are unable or unwilling to understand the bigger picture.

And this is the problem everywhere these days. The railway (or any other body for that matter) has to be seen to be 'doing something'. If they do nothing then they run the risk of the lawyers.

I feel no more or less safe travelling by train now than I did 10, 20 years ago.

 

[Old Timer]

Working abroad helps to put a lot of this risk-averse UK safety culture we have in context when some of our high risks include being eaten by Alligators, bitten by poisonous snakes/spiders (and I mean fast-acting toxins not some slight skin prick), various insect and water-borne diseases, trains falling down mountains following broken rails/track geometry defects, walking over trestle bridges, sudden flash floods, etc, etc.

I am currently trying to bring some semblance of common sense to an organisation that is almost moribund through Safety Professionals without a modicum of common sense.

So many people fail to understand that a risk assessment can simply write down a risk as suitably improbable or insignificant, and even Method Statements can be left unchecked in detail provided there is a sound rationale.

HMRI/HSE require only that due diligence and care is required, but this has been taken to unbelievable lengths by some people.

There is much that could be learnt from the European approach to safety and, more importantly, personal responsibility.

 

[moggie]

Come off it OT are you seriously suggesting that collisions which resulted in a host of fatalities after SPAD's in recent years, prior to network installation of TPWS, would have resulted in identical or worse fatal outcomes if TPWS had been installed. It was precisely because the frequency of such collisions had outstripped the statistical likelihood of such collisions occurring that the government ordered BR to commission pilot ATP installation. TPWS has been a life saver in the event the powers that be decided ATP as piloted, was unafordable. I personally cannot prove this statement but if you are saying that the proven reduction in collisions due to TPWS intervention has statistacally made no difference to the statistical number of fatalities that would otherwise have occurred if TPWS intervention had not occurred then I would say that statistacally the probability is that you are mistaken in your ascertion. You and I both know there are lies, statistics and the real world. I for one have a lot of faith in the presence of this system and the ongoing developments in the application rules until the holy grail of full ATP supervision is upon us (which I believe will be some considerable time yet). You make the point that the introduction of TPWS increases the statistical likelihhod of maintenance staff suffering a fatality. This is true but perhaps overstated. Most of the kit is not in the four foot. That that is in no more of a hazard that AWS (TPWS is not fitted to all signals) so is therefore less of a hazard than AWS. Are you suggesting that it would be safer to remove AWS? Inthe world of stats I guess the answer must be yes?

I would not dispute that money would be well spent on renewing life expired interlockings but it has been shown that as a industry the UK network was losing the argument that red signals and good training of drivers was sufficient for ALL trains to stop at red signals - like it or not something had to be done to restore the shattered (no pun intended) public confidence.
A knackered interlocking is easy to sort in the short term. Just disconnect it, clip and padlock the points, put a temporary auto section / limited route interlocking in and do without a few routes for as long as it takes to restore the signalling to it's full capability (with an ISSI!). The safety is in the responsible and timely intervention by the local signal engineer who decides when the existing one is beyond use. That I'm sure is not so easy but we all carry the burden of responsibility in our respective roles.

All we have to do now is sort our level crossings out from the idiot fraternity (with the greatest respect to those who lost their lives at Moreton on Lugg who were clearly innocent of any misuse). I've no doubt that you know of other areas also.

 

[Old Timer]

Hi Moggie, a well formulated response as always.................................however.

I am on the way to the airport so I shall have of necessity to keep my response briefer than I would prefer. Please bear with me.

Firstly I am looking at the subject from a whole-system perspective whereas you are wearing your Signalling Design cap.

There is no dispute of the fact that the Research project concluded that through its lifespan, greater staff fatalities would occur than passenger lives saved. It crossed my desk when I was in a different post. Remember that whole-system looks at things like road traffic accidents to staff responding. It is not confined to being on the track.

Lets look at some recent accidents.

Colwich Jct - Not preventable by standard TPWS
Clapham Jct - Not TPWS preventable
Purley - Possibly - needs to be looked at
Stafford station - Not TPWS preventable
Gailey (Stafford) - Vehicle defect (if I recall right)
Southall - Not TPWS preventable - AWS Isolated
Ladbroke Grove - Not preventable by standard TPWS
Hatfield - Track defect
Potters Bar - Points defect
Great Heck - Road vehicle incursion
Ufton Nervett - Road vehicle incursion
Grayrigg - Points defect

So you see very little would have been prevented by TPWS.

Now lets examine some further aspects.

As I assume you know, the great majority of SPADs (98% last time I looked at the figure) are contained within the overlap and thus cannot enter into a collision. Of the remaining ones which exit the overlap, again the majority are stopped before reaching conflict.

In practically every case where TPWS has been triggered, the Driver has already taken the train under control and is either in full service or emergency, thus the TPWS intervention has again not prevented a collision, because the train was already braking.

Rail vehicles are now much more robust than before, and the passenger area is normally very secure. Even moderate speed collisions will not result in major injuries owing to the crush zones, and once again windows are glazed to contain.

I grant you that we have no evidence yet from a high speed collision involving new rolling stock (Grayrigg does not count) however as pointed out above in every SPAD case so far the train has been braking before TPWS intervened, and the intervention has not brought about any greater retardation or mitigation of the outcome.

Turning now to Interlockings. We both know the state of both interlockings and loc cases in certain areas. Taking the risk profile from a failure of one of those you get a much better return on safety money by renewing the interlocking than you do TPWS. Not me speculating, this is established fact.

Now how many schemes have been deferred to the great God of TPWS, and how many installations are in dire need of attention ?

Whole hoards of much needed signalling design was put on hold in order to satisfy the fitting of TPWS to signals that in many cases would rarely be at danger. You know this too.

To suggest that you can simply take an interlocking out of use and clip up or design in through routes, or impose TBW ignores the fact that NR seem to be incapable of operating any degraded form of operation or Possession without incident, something you can see every day almost in the various logs.

With TBW you have greatly increased the exposure of staff to risk, you also have the new risk of trains stopping at signals not fitted with TPWS at all - It will be interesting when there is a rear end collision from a SPAD at a non fitted signal in rear. TBW and disrupted working increass the number of reds and ups the SPAD risk. This SPAD risk will be created at signals not fitted in most cases as traffic backs up.

There is no simple answer to this and I am not saying totally that TPWS may not save a life at some point, (I am struggling here to recall a collision where one would have been or a near miss where the Driver was NOT braking at the time - thus rendering TPWS ineffective anyway) but the effective use of limited resources demands that it should be spent on projects which bring about the best return on the money not on knee-jerk solutions which are driven by Media and other pressure and of themselves bring about little or no ultimate benefit.

To me at this stage, TPWS fits into that category.

TPWS to me is only effective where the train is not under the control of the Driver or he is speeding recklessly - something I fail to see occur.

How many accidents and incidents have occurred where money has not been available to bring about improvements (level crossings being one example) because it has been wasted on TPWS fitment ?

 

[Ploughman]

Can anyone answer the question as to why in many track renewal schemes pre TPWS the policy was to remove cabling from ducting and install UTXs. Sensible policy keep it tidy and out of the way.
Then along came TPWS and cables scattered all over the place. Even to the extent of cables on opposite sides of the tracks feeding the other side ie the UP side cable route connected to the DOWN side and Vice versa.
It made trying to do a renewal on a 4 track line difficult if you had 2 tracks live alongside.

 

[GB]

Southall - Not TPWS preventable - AWS Isolated

It *may* not have prevented a collision but it would have reduced speed to the extent it *may* have greatly reduced the impact that *may* have saved just a few more lives.

 

[moggie]

OT - your considered response as always makes many good points taken from a wide perspective. A couple of observations I'd throw is to the debate.

From your list as a good set of recent examples I would say that you are correct in all cases when considering 'standard' TPWS. For the benefit of others on this forum I'd like to think that 'standard' TPWS fitment criteria has moved on a little since the early days such that all new signalling installations must now satisfy the requirement to stop a train at ful linespeed under emergency braking within the 'safe overrun distance' up to 125 mph approach speeds through a combination of TPWS loops and / or signalling control techniques. I know some of the latter have not met with universal approval. I believe that the network is progressively being brought up to these standards from the original 'throw it in quck' approach adopted by Railtrack in their days of need. So I would say that Colwich, Ladbroke Grove and Purley would now be prevented - not bad in terms of effectiveness. I grant you that the other incidents would not have been influenced by TPWS on the facts as I understand them. I guess the point that I was reacting to is that now the sytem is in place the only TPWS expeniditure is now generally part of an overall renewals or modernisation project and as such is likely to be a relatively small part of the overall costs. Personally I don't believe it was a knee jerk reaction as it was surely the inevitable consequence resulting from a series of high profile and tragic accidents that the Rail industry was seemingly powerless to prevent with the existing technology at it's (affordable) disposal.

Now, reagrding your point on interlockings - what i was decribing is in effect a cheap and limited facilty temporary interlocking as has been provided from time to time around the UK - not TBW. Perfectly safe and operated normally from the main panel under normal TCB regs but deliberatley provided with limited functions so as to implement quickly for the core routes only. What doesn't get included gets C&P'd for the duration. The all singing replacement usually takes a little longer. Of course a well planned and funded programme of renewals should avoid this but we both know this is not always the case. Without wishing to stir politics again I know of lots of signal engineers having been sat around without any work long before TPWs came along but with a list of Interlockings needing renewal to keep us all busy for the rest of our working lives - It's improved I'm sure, but certainly has not been eradicated by a long way. Lots of clever work by the maintenance / spot renewals teams keep them going it seems.

As always OT - good to debate the issue with you. I'm glad I only had to respond to your 'brief' reply!

Re ploughmans point of UTX's - simply to implement the TPWS national programme as cheap and quickly as possible. Plastic pipes are off the menu again now I believe.

 

[Ploughman]

Its just that it was frustrating to complete a project with UTXs and literally a week later the site was blighted by orange ducts.
It could have been accomodated in the work a week or a fortnight earlier.

 

[Old Timer]

It *may* not have prevented a collision but it would have reduced speed to the extent it *may* have greatly reduced the impact that *may* have saved just a few more lives.

All that TPWS does is to demand a brake application via the AWS system.

TPWS is not "wired in" to the braking system direct but initiates the brake application through the AWS non-cancellation control.

Thus it would have had no impact upon the outcome of Southall, if you will excuse the unintentional pun.