HSTs - Are they sufficently crashworthy now, should they be withdrawn?

[Bletchleyite]

The question to ask, I suppose, is how would a brand new DMU such as a Cl 195 have fared in comparison with the HST.

Theoretically better. But theoretically the lateral dampers are not supposed to fall off.

The damage done to the 800 in the 10mph speed difference crash at Neville Hill looks quite bad. Perhaps they should be withdrawn too.

Report 13/2020: Collision and derailment at Neville Hill

RAIB has today released its report into the collision and derailment at Neville Hill, 13 November 2019.

www.gov.uk

That's a crumple zone doing its job.

There is so much nonsense and hyperbole about this.

To suggest they “offer nothing more than weather protection” is just utter drivel. They met the collision resistance standards at the time they were built and (as posted elsewhere) that they offer better protection than 1960s designs and at least match the likes of Class 150.

I got bored of trying to have rational debate with him before I asked the question "had we best take all the 15x and 16x out of service now too", as if the answer is "no", he's talking nonsense.

I am of the view that they should be replaced with more 80x (both at ScotRail and GWR) but I think shouting about things being unsafe is really unhelpful. And comparing a 155mph design (390) with a 125mph design (HST) is just silly, of course a 155mph design will be safer at a lower speed.

 

[najaB]

That's a crumple zone doing its job.

Yes. But it is slightly worrying how much it crumpled given the low speeds involved. Momentum increases as the square of velocity so there would be a *lot* more crumple if the collision was at a higher speed.

 

[snowball]

Yes. But it is slightly worrying how much it crumpled given the low speeds involved. Momentum increases as the square of velocity so there would be a *lot* more crumple if the collision was at a higher speed.

Momentum is proportional to velocity. Kinetic energy is proportional to the square of the velocity.

 

[najaB]

Momentum is proportional to velocity. Kinetic energy is proportional to the square of the velocity.

D'oh! I actually meant kinetic energy.

 

[MarkyT]

I am of the view that they should be replaced with more 80x (both at ScotRail and GWR) but I think shouting about things being unsafe is really unhelpful. And comparing a 155mph design (390) with a 125mph design (HST) is just silly, of course a 155mph design will be safer at a lower speed.

Maybe 80x is a bit over the top for these regional express services that don't exceed 100mph, but something multimode equipped with autonomous power as well as overhead pickup seems reasonable to fit with the Scottish electrification strategy which sees wires to Aberdeen at least and perhaps partway via Aviemore to Inverness which could plausibly allow use of battery power for the unwired extremities (other local services around Inverness which would only normally encounter wires at Aberdeen say might be good H2 candidates) It could take up to a decade to complete such wiring and introduction of a new fleet would take a few years at least and ideally be synchronised with this work. The continued use of HSTs on secondary routes only two or three years after they were in front line long distance high speed services with very high peak loading doesn't strike me as being intrinsically unsafe, although firm plans need to be put in place for their replacement in a reasonable timeframe. What we don't need is a hasty kneejerk replacement with yet more standard brand new DMUs that will continue to pollute for the next 40 years. In the meantime perhaps some small safety modifications to the mk3s and power cars might be justified, just as applied to Mk1 based vehicles until they could practically be replaced. Please let's wait for the full report for more nuanced consideration of the facts. If these trains are 'deathtraps' today then the risk three years ago must have been high too when they were in front line service with much higher passenger numbers on busier parts of the network.

 

[Ianno87]

I got bored of trying to have rational debate with him before I asked the question "had we best take all the 15x and 16x out of service now too", as if the answer is "no", he's talking nonsense.

I am of the view that they should be replaced with more 80x (both at ScotRail and GWR) but I think shouting about things being unsafe is really unhelpful. And comparing a 155mph design (390) with a 125mph design (HST) is just silly, of course a 155mph design will be safer at a lower speed.

Rolling Stock crashworthiness is, in effect, the last line of defense in passenger and traincrew safety. I'm always of the view that the best line of safety is not to have trains de-rail/collide in the first place.

The important point (which I think is getting lost in the Twitter to-and-fro) is that safety is a continuous improvement thing. HSTs have not suddenly become unsafe, they are as safe/unsafe as they have always been (in crashworthiness terms), but they are not in line with what happen to be the current standards (and thus more modern trains). And so their time is coming round as the next "low hanging fruit" to improve the level of overall system safety (which, perhaps, should be accelerated).

It's an argument that equally applies to infrastructure too that doesn't meet current standards; level crossings being an example of a continuous improvement thing; taking opportunities as they arise to either upgrade or close (but the safety of them being carefully managed in the meantime). There are countless other example (e.g. buffer stop overruns not within current standards), that get treated as and when opportunities arise, and mitigated in the meantime (with TPWS, defensive driving policies, etc.)

 

[Bletchleyite]

Rolling Stock crashworthiness is, in effect, the last line of defense in passenger and traincrew safety. I'm always of the view that the best line of safety is not to have trains de-rail/collide in the first place.

Certainly.

The important point (which I think is getting lost in the Twitter to-and-fro) is that safety is a continuous improvement thing. HSTs have not suddenly become unsafe, they are as safe/unsafe as they have always been (in crashworthiness terms), but they are not in line with what happen to be the current standards (and thus more modern trains). And so their time is coming round as the next "low hanging fruit" to improve the level of overall system safety (which, perhaps, should be accelerated).

Probably so, though to some extent moving them to slower regional services from 125mph mainline services has already started down that line. I'd probably get an 80x order in, as I've said, but no real hurry, and the shouting that is being done on Twitter and in that newspaper article is just utter hyperbole.

Are they as safe as 390s/80x? Clearly not.

Are they safer than driving? Pretty certainly.

Are they less safe than a 158, 170, 195 or similar? Debatable, if only because of the heavy locomotive that's on the front before you get anywhere near the passengers (though obviously that doesn't do anything for the driver). Maybe the 195 would be safer as it's very new, but the Turbostar/Turbo/Sprinter families I would very, very much doubt. (Just look at how the HST demolished the front car of the Turbo to nothing at one of the Paddington accidents - destroyed to the point that anyone looking at the photos would believe a 2-car, not 3-car, unit was involved).

Is the driver who goes on about being "fearful and angry" when driving one being just a little bit silly? Yes, I'm sure he doesn't feel that way when he drives his car*, which is much more dangerous. That doesn't mean things shouldn't be made safer for him, of course, but he has a far higher chance of dying in a car crash on his way to book on than when driving his train.

Therefore withdrawing them immediately would be negative because more people would drive to avoid overcrowding. But making them (and other ex-BR diesel-only stock) next in the line for replacement with bi-mode or other non-pure-diesel kit (for a double benefit) would make sense.

It's an argument that equally applies to infrastructure too that doesn't meet current standards; level crossings being an example of a continuous improvement thing; taking opportunities as they arise to either upgrade or close (but the safety of them being carefully managed in the meantime). There are countless other example (e.g. buffer stop overruns not within current standards), that get treated as and when opportunities arise, and mitigated in the meantime (with TPWS, defensive driving policies, etc.)

That's true.

* Bicycles are also available, of course, if he doesn't drive. From a personal perspective, I have been in accidents on modes of transport that have been a threat to my life/could have caused life changing injuries:
Walking: 0
Train: 0
Air: 0
Ferry: 0
Car: 0 (2 minor accidents but both low speed and so not a threat to my life)
Bicycle: 2-3 depending how close to the line you'd judge it - certainly one major one that could easily have caused death and was a split second away from doing so

 

[Ianno87]

Is the driver who goes on about being "fearful and angry" when driving one being just a little bit silly? Yes, I'm sure he doesn't feel that way when he drives his car*, which is much more dangerous. That doesn't mean things shouldn't be made safer for him, of course, but he has a far higher chance of dying in a car crash on his way to book on than when driving his train.

It focuses the mind how much implict trust is placed in the standard of the P-Way day in, day out. I think that almost every single time I pass over that set of points at Potters Bar. I respect people who look after the track; I doubt I could sleep at night with the responsibility I'd have on my shoulders.

 

[AlterEgo]

Yes, we do. However some people seem to be jumping to the conclusion rather than waiting for the results of the investigation.

Indeed, and we can count our erstwhile civil engineer friend among those, speaking outside his specialism - not for the first time.

 

[43096]

Is the driver who goes on about being "fearful and angry" when driving one being just a little bit silly? Yes, I'm sure he doesn't feel that way when he drives his car*, which is much more dangerous. That doesn't mean things shouldn't be made safer for him, of course, but he has a far higher chance of dying in a car crash on his way to book on than when driving his train.

I’d suggest it’s either a driver with an axe to grind with the company, or, if they really feel like that, perhaps they shouldn’t be driving trains for a living.

 

[Bletchleyite]

I’d suggest it’s either a driver with an axe to grind with the company, or, if they really feel like that, perhaps they shouldn’t be driving trains for a living.

Or perhaps he has been seriously affected by the tragedy (maybe he knew one of the traincrew personally?) and so needs some counselling to help him come to terms with that?

Either way, driving an HST is not something to be scared of (if driving trains is your job), because it's much safer than driving a car. The situation would be similar to a pilot who developed a fear of flying.

It focuses the mind how much implict trust is placed in the standard of the P-Way day in, day out. I think that almost every single time I pass over that set of points at Potters Bar. I respect people who look after the track; I doubt I could sleep at night with the responsibility I'd have on my shoulders.

Very true - much like the trust in Air Traffic Control and similar, but trains don't have a TCAS equivalent to avoid something happening due to a bad bit of track

 

[35B]

Theoretically better. But theoretically the lateral dampers are not supposed to fall off.



That's a crumple zone doing its job.



I got bored of trying to have rational debate with him before I asked the question "had we best take all the 15x and 16x out of service now too", as if the answer is "no", he's talking nonsense.

I am of the view that they should be replaced with more 80x (both at ScotRail and GWR) but I think shouting about things being unsafe is really unhelpful. And comparing a 155mph design (390) with a 125mph design (HST) is just silly, of course a 155mph design will be safer at a lower speed.

Both of those analyses presume that the only safety calculation to be done is that internal to the railway system. The 390s have, at least to an extent, increased the risk to travellers - this traveller, for one, has chosen to drive (intrinsically higher risk) rather than endure one of those not so padded cells. As an ECML resident, the 80x units have a similar effect on me - and that's without considering some of the implications of Neville Hill where, IMHO, the broken fibreglass was not the concerning outcome of that coming together.

 

[Ianno87]

Both of those analyses presume that the only safety calculation to be done is that internal to the railway system. The 390s have, at least to an extent, increased the risk to travellers - this traveller, for one, has chosen to drive (intrinsically higher risk) rather than endure one of those not so padded cells. As an ECML resident, the 80x units have a similar effect on me - and that's without considering some of the implications of Neville Hill where, IMHO, the broken fibreglass was not the concerning outcome of that coming together.

Although, unless you have evidence to the contrary, new stock in general attracts more passengers to rail or accommodates more passengers overall than old stock.

I.e. anyone choosing not to travel on an 80x for comfort reasons is probably outweighed by 2 people who don't care and are now incentivised to travel. Ergo still a net improvement in safety.

 

[northernbelle]

Yes. But it is slightly worrying how much it crumpled given the low speeds involved. Momentum increases as the square of velocity so there would be a *lot* more crumple if the collision was at a higher speed.

Not really. The more the crumple zone crumples, the less risk there is of the human areas becoming intruded upon.

The front end being smashed to pieces in a collision is far better than it not absorbing the energy which translates to that energy being absorbed by other things such as the passenger space. Compare the buffer stop collision at Cannon Street with similar incidents involving newer stock.

 

[GlitterUnicorn]

Is the driver who goes on about being "fearful and angry" when driving one being just a little bit silly? Yes, I'm sure he doesn't feel that way when he drives his car*, which is much more dangerous. That doesn't mean things shouldn't be made safer for him, of course, but he has a far higher chance of dying in a car crash on his way to book on than when driving his train.

I’d suggest it’s either a driver with an axe to grind with the company, or, if they really feel like that, perhaps they shouldn’t be driving trains for a living.

Or perhaps he has been seriously affected by the tragedy (maybe he knew one of the traincrew personally?) and so needs some counselling to help him come to terms with that?

Either way, driving an HST is not something to be scared of (if driving trains is your job), because it's much safer than driving a car. The situation would be similar to a pilot who developed a fear of flying.

Can we avoid getting into a discussion about the character of the driver?

 

[Ianno87]

Can we avoid getting into a discussion about the character of the driver?

It is, however, merely the quotes of one driver, and it's legit to question whether that is representative of Scotrail drivers in general. Part of me says that they must know they are driving 40+ year old pieces of kit to be doing the job.

 

[najaB]

Not really. The more the crumple zone crumples, the less risk there is of the human areas becoming intruded upon.

The front end being smashed to pieces in a collision is far better than it not absorbing the energy which translates to that energy being absorbed by other things such as the passenger space. Compare the buffer stop collision at Cannon Street with similar incidents involving newer stock.

I understand how crumple zones work, the point I was making is that this was a very low-speed collision compared to the speeds that the trains will regularly reach (c. 15mph vs 125mph). There's only so much zone to crumple before you intrude into the safety cell, if so much of it was used with this collision how much is going to be used when there's nearly 70 times more energy to absorb?

One wonders if they've been designed using the same philosophy as some Japanese commuter trains where the driver's cab is considered to be part of the crumple zone!

Crumple zone - Wikipedia

en.wikipedia.org

 

[43096]

Can we avoid getting into a discussion about the character of the driver?

If the driver is prepared to go to the press (and presumably breaching their employer's company policy) and be quoted in what is essentially a load of hyperbolic twaddle, then they've got to expect questions to be asked as to why they've done it.

 

[tbtc]

There are a few excuses coming out about how railway professionals should be happy putting up with all of the problems in their workplace because these old Apples are still better than Oranges - the debate should be about how good these old Apples are, in terms of how they compare to other Apples and the standards people expect from an Apple in 2021

driving an HST is not something to be scared of (if driving trains is your job), because it's much safer than driving a car

Are they safer than driving? Pretty certainly

Is the driver who goes on about being "fearful and angry" when driving one being just a little bit silly? Yes, I'm sure he doesn't feel that way when he drives his car*, which is much more dangerous. That doesn't mean things shouldn't be made safer for him, of course, but he has a far higher chance of dying in a car crash on his way to book on than when driving his train

It's not about comparisons with cars - cars and trains have always ben subject to different standards - just like we expect planes to comply with stricter safety (that's just how it is - whether people agree with it or not)

Similarly, it's not about whether the HSTs were "safe" in the 1970s - it's about whether they meet the high standards that people expect from railways in 2021

Given all of the "safety" issues that we've seen threats of industrial action over in recent years, it's funny how some people turn a blind eye to modern problems with their favourite old trains

I don't know how safe HSTs are, I don't know what the investigations will say, but let's be honest about the yardsticks - they need to be safe enough for the modern railway (rather than any bogus comparisons)

 

[Bletchleyite]

Although, unless you have evidence to the contrary, new stock in general attracts more passengers to rail or accommodates more passengers overall than old stock.

I.e. anyone choosing not to travel on an 80x for comfort reasons is probably outweighed by 2 people who don't care and are now incentivised to travel. Ergo still a net improvement in safety.

The F*nsa S*phia is very much a matter of opinion. Some people love them. I'm less of a fan as is well known, but they would not put me off using an 80x entirely, indeed I quite like the units in most other ways, particularly when effort has gone into the interior styling e.g. TPE. The 80x is no Pendolino - the windows are a decent size, I fit in every seat (unusual!) and the overhead luggage space is excellent.

I suspect the EMR units with FISA seats will be quite nice.

So in summary I don't think anyone is going to be put off using rail due to an 80x, and to be honest Pendolinos are generally quite well regarded, and the First Class is absolutely excellent, easily the best in the UK.

And if you get something like the GA FLIRTs in, that would definitely attract passengers - they really are lovely.

Edit: 80x, due to their appearance, also have a "cool, it's a bullet train" marketing thing as well.

 

[najaB]

Similarly, it's not about whether the HSTs were "safe" in the 1970s - it's about whether they meet the high standards that people expect from railways in 2021

To be fair, what really matters is if they are safe enough - meaning that the risk of death/injury is lower than if the equivalent number of journeys were made by alternate means (e.g. car, bus) - rather than if they are as safe as they possibly could be.

 

[Bletchleyite]

To be fair, what really matters is if they are safe enough - meaning that the risk of death/injury is lower than if the equivalent number of journeys were made by alternate means (e.g. car, bus) - rather than if they are as safe as they possibly could be.

A lot of people have difficulty with the fact that safety is never an absolute. If we consider them being pulled from service now, the result would be overcrowded single 158s replacing them. That would push people into cars, and thus be a safety negative. However, starting to think about ordering replacements now with a view to being in service in say 3-5 years (rather than the originally planned 9 years) may well be a good idea. Replacing them 5-6 years early won't substantially affect the cost.

 

[edwin_m]

To suggest they “offer nothing more than weather protection” is just utter drivel. They met the collision resistance standards at the time they were built and (as posted elsewhere) that they offer better protection than 1960s designs and at least match the likes of Class 150.

There was a picture in Modern Railways sometime in the 70s of a lowish-speed collision between a HST and a 47. The locomotive had a HST-shaped indentation in the cab end, probably pushed back a couple of feet at the deepest.

Both of those analyses presume that the only safety calculation to be done is that internal to the railway system. The 390s have, at least to an extent, increased the risk to travellers - this traveller, for one, has chosen to drive (intrinsically higher risk) rather than endure one of those not so padded cells. As an ECML resident, the 80x units have a similar effect on me - and that's without considering some of the implications of Neville Hill where, IMHO, the broken fibreglass was not the concerning outcome of that coming together.

The concerning aspect for me was the extent of derailment, including being foul of the adjacent track. This was apparently a combination of the coupling bars having to be much longer because of the vehicle length and overhang on curves, so they effectively pole-vaulted the car ends into the air, and the speed being too low to initiate progressive deformation of those coupling areas that would have absorbed some of the crash energy.

Not really. The more the crumple zone crumples, the less risk there is of the human areas becoming intruded upon.

And if the crumple zone has deformed to its maximum extent, the rest of the bodyshell is designed to be at least as rigid as a Mk3.

However, I'm pretty sure that railway crumple zones have saved no lives in the UK, mainly because TPWS and other safety initiatives have largely eliminated the end-on collisions where they might mitigate the consequences. They may however have led to more likelihood of a vehicle being written off if involved in an accident, because once crumpled the shell is probably beyond economic repair.

 

[Bletchleyite]

The concerning aspect for me was the extent of derailment, including being foul of the adjacent track. This was apparently a combination of the coupling bars having to be much longer because of the vehicle length and overhang on curves, so they effectively pole-vaulted the car ends into the air, and the speed being too low to initiate progressive deformation of those coupling areas that would have absorbed some of the crash energy.

Interesting you raise that, because 26m 80x vehicles aren't like 26.4m UIC stock - to fit that length in for the UK they have very long overhangs and bogie centres similar to a 23m vehicle - so might an 80x perform worse in that specific incident?

A FLIRT with its Jacobs bogies would likely perform best?

 

[MarkyT]

A lot of people have difficulty with the fact that safety is never an absolute. If we consider them being pulled from service now, the result would be overcrowded single 158s replacing them. That would push people into cars, and thus be a safety negative. However, starting to think about ordering replacements now with a view to being in service in say 3-5 years (rather than the originally planned 9 years) may well be a good idea.

And any such major fleet renewal decisions must be made in full cognisance of the extent and timescales of the Scottish electrification strategy, as I stated earlier. I think a target to have such a new fleet in full service within a decade is reasonable. Of course if the condition of the current fleet is deteriorating faster than anticipated, then rising costs keeping them rolling could seal their fate more quickly.

 

[northernbelle]

And if the crumple zone has deformed to its maximum extent, the rest of the bodyshell is designed to be at least as rigid as a Mk3.

However, I'm pretty sure that railway crumple zones have saved no lives in the UK, mainly because TPWS and other safety initiatives have largely eliminated the end-on collisions where they might mitigate the consequences. They may however have led to more likelihood of a vehicle being written off if involved in an accident, because once crumpled the shell is probably beyond economic repair.

Indeed - although the fact that the crumple zone was there would, in theory, mean the energy being exerted on the rest of the bodyshell would be less than a vehicle without one.

Your second point is hard to quantify as there have been cases of end-on collisions in recent years - Kirkby, the Chester Voyager and the coming together of the 150 and HST at Plymouth. That's without a number of near-misses such as the Wootton Bassett SPAD or Edinburgh sleeper runaway. With that in mind, I do hope the RAIB investigation for Carmont will look at crashworthiness and performance of rolling stock in an accident - especially older vehicles and those that have received modification in their life. Although crashworthiness is the last line of defence, I think it's probably unrealistic to think that trains won't crash into things - even if it's not another train.

 

[Bletchleyite]

Indeed - although the fact that the crumple zone was there would, in theory, mean the energy being exerted on the rest of the bodyshell would be less than a vehicle without one.

Your second point is hard to quantify as there have been cases of end-on collisions in recent years - Kirkby, the Chester Voyager and the coming together of the 150 and HST at Plymouth. That's without a number of near-misses such as the Wootton Bassett SPAD or Edinburgh sleeper runaway. With that in mind, I do hope the RAIB investigation for Carmont will look at crashworthiness and performance of rolling stock in an accident - especially older vehicles and those that have received modification in their life. Although crashworthiness is the last line of defence, I think it's probably unrealistic to think that trains won't crash into things - even if it's not another train.

I'd venture that a landslip (as happened here, I think?) may well now be the most likely thing for a train to crash into (because we've got quite good at preventing trains crashing into other trains), or on some lines a large, heavy vehicle on a level crossing, and that might well bring its own design considerations.

 

[bramling]

Rolling Stock crashworthiness is, in effect, the last line of defense in passenger and traincrew safety. I'm always of the view that the best line of safety is not to have trains de-rail/collide in the first place.

The important point (which I think is getting lost in the Twitter to-and-fro) is that safety is a continuous improvement thing. HSTs have not suddenly become unsafe, they are as safe/unsafe as they have always been (in crashworthiness terms), but they are not in line with what happen to be the current standards (and thus more modern trains). And so their time is coming round as the next "low hanging fruit" to improve the level of overall system safety (which, perhaps, should be accelerated).

It's an argument that equally applies to infrastructure too that doesn't meet current standards; level crossings being an example of a continuous improvement thing; taking opportunities as they arise to either upgrade or close (but the safety of them being carefully managed in the meantime). There are countless other example (e.g. buffer stop overruns not within current standards), that get treated as and when opportunities arise, and mitigated in the meantime (with TPWS, defensive driving policies, etc.)

I’d tend to agree that, as a passenger, crashworthiness isn’t really something worth devoting too much thought to - the chances of being involved in an accident are absolutely minimal, certainly fractional compared to road transport. Preventing trains having accidents is far more beneficial.

Back in the 1990s, we knew Mk1s weren’t wonderful in terms of crashworthiness, and this was more due to a specific characteristic in their design which no current stock shares. Despite being well aware of the overriding risk on a Mk1, this didn’t make me give a second thought to tanking along in a VEP at 90 mph, and nor should it have done - the Mk1s completed many millions of miles of safe travel.

Having said all that, there is perhaps more of an issue with HST cabs. For the well-known HST accidents it’s a matter of conjecture how much of an effect this might have had - though for both Carmont and probably Ufton it’s a matter of legitimate concern. However one does have to question how much protection the structure of an HST cab provides for something more common, like hitting a tree for example.

I think cab safety is probably more of an issue than Mk3 safety, and I suspect we will hear more on this.

 

[edwin_m]

Interesting you raise that, because 26m 80x vehicles aren't like 26.4m UIC stock - to fit that length in for the UK they have very long overhangs and bogie centres similar to a 23m vehicle - so might an 80x perform worse in that specific incident?

A FLIRT with its Jacobs bogies would likely perform best?

I think that was part of it re the 80x - the long overhang means that adjacent coaches move a long way apart laterally on reverse curves such as crossovers. The long coupling is necessary to take up that movement without pulling the two bodies into contact or off the rails.

Not sure how Jacobs bogies play with intermediate crumple zones - there would have to be some kind of frangible element in the body-bogie connection so the two bodyshells could contact and start crumpling. Articulated trains such as TGVs have tended to stay well in line during high speed derailments, but that might mean a very sudden stop if there was an obstruction in the way, whereas a non-articulated train might have lost more energy by jack-knifing and otherwise deforming. But I'm of the view that survivability depends far more on the exact sequence of events in an accident than on the structural strength of the train(s) involved.

Indeed - although the fact that the crumple zone was there would, in theory, mean the energy being exerted on the rest of the bodyshell would be less than a vehicle without one.

Your second point is hard to quantify as there have been cases of end-on collisions in recent years - Kirkby, the Chester Voyager and the coming together of the 150 and HST at Plymouth. That's without a number of near-misses such as the Wootton Bassett SPAD or Edinburgh sleeper runaway. With that in mind, I do hope the RAIB investigation for Carmont will look at crashworthiness and performance of rolling stock in an accident - especially older vehicles and those that have received modification in their life. Although crashworthiness is the last line of defence, I think it's probably unrealistic to think that trains won't crash into things - even if it's not another train.

Of those, only the Edinburgh sleeper and the Chester Voyager were designed to a standard that required crumple zones. There is no visible deformation to the Voyager in the photographs from Chester, so the crumple zone didn't come in to play here and the result would have been similar if it hadn't been there. If the train at Wootton Bassett had been a modern one then the chain of events that might have resulted in the accident would have been impossible, illustrating how other safety innovations tend to reduce the likelihood of accidents where crumple zones might otherwise reduce the severity.

I'd venture that a landslip (as happened here, I think?) may well now be the most likely thing for a train to crash into (because we've got quite good at preventing trains crashing into other trains), or on some lines a large, heavy vehicle on a level crossing, and that might well bring its own design considerations.

The HGV collision scenario is one where controlled deformation of the cab end can actually make a difference.

 

[Bletchleyite]

I think cab safety is probably more of an issue than Mk3 safety, and I suspect we will hear more on this.

I would agree, and I wouldn't rule out that some form of strengthening is carried out to the cabs but the HSTs remain in service for the planned further 9 years or so.