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Collision and derailment at Neville Hill Depot (13/11/2019)

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sprinterguy

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Its very concerning that the 800 took so much damage compared to the HST

cheap trains arn’t always the safest option

just think if this was a serious crash, how would the 800 manage in that? o_O
It's been thoroughly discussed that the damaged area of the class 800 was a purely aesthetic and sacrificial section of nose cone, designed to break up in the event of an impact to help disperse kinetic energy. The survival cell, which includes the drivers cab, appears to be entirely intact. That's significantly safer for the driver than an HST cab in the case of a high energy collision, which is glass reinforced plastic (GRP) all the way back to the bulkhead behind the cab door!

The derailment of three bogies of 800109 in a fairly low speed collision was more surprising, and hopefully the RAIB report may offer some insight into how that occurred.
 
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Bantamzen

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Its very concerning that the 800 took so much damage compared to the HST

cheap trains arn’t always the safest option

just think if this was a serious crash, how would the 800 manage in that? o_O

This has already been covered further up the thread, whilst the damage looks superficially bad, the nose cone is designed to do that to absorb some of the energy of an impact. If the train were really badly damaged it would not have moved under it's own power to Doncaster, albeit with one carriage on skates.
 

800002

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Incidentally, could it have been down to the wheel profile?
It's unclear to me which of the bogies wore skates seen en route to Doncaster - as in on which number coach in the formation (from the incident direction of travel). Why was that bogie affected so greatly and not the other derailed ones?
 

hwl

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Its very concerning that the 800 took so much damage compared to the HST

cheap trains arn’t always the safest option

just think if this was a serious crash, how would the 800 manage in that? o_O
1. They aren't cheap
2. The bit that crumpled was designed to crumple easily - it isn't part of the crash structure shown in the image below
The damage may look bad it was only lightweight fibreglass for aerodynamics...


upload_2019-11-27_16-46-28.png
 
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RealTrains07

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1. They aren't cheap
2. The bit that crumpled was designed to crumple easily - it isn't part of the crash structure shown in the image below
The damage may look bad it was only lightweight fibreglass for aerodynamics...


View attachment 70870
Well thats a relief, good thing too considering newer trains don’t look crash resistant from first glances
 

Raul_Duke

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Well thats a relief, good thing too considering newer trains don’t look crash resistant from first glances

Neither do older ones. There’s not so much you can do when big heavy things hit each other with any kind of momentum.
 

43066

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Neither do older ones. There’s not so much you can do when big heavy things hit each other with any kind of momentum.

It’s such a warm fuzzy feeling when your traction course instructor tells you that the driver’s cab itself forms part of the crumple zone. :D
 

D6700

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Incidentally, could it have been down to the wheel profile?
It's unclear to me which of the bogies wore skates seen en route to Doncaster - as in on which number coach in the formation (from the incident direction of travel). Why was that bogie affected so greatly and not the other derailed ones?
813109, which would be the third vehicle. Cracked gear box, I've heard.
 

ComUtoR

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It’s such a warm fuzzy feeling when your traction course instructor tells you that the driver’s cab itself forms part of the crumple zone. :D

I asked, many moons ago now, where the crumple zone was.

"about a foot behind your head" was the response.
 

ManOnATrain

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If the entire nose cone was destroyed at 15mph, that means a dead driver at higher speed collisions. Not great. What's the maximum speed collision possible on the ECML?
 

daikilo

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Hopefully not, it is quite feasible to have an initial crumple zone in the nose and a second behind the driver's safety zone which will be heavily reinforced. The only issue is the acceleration rate that the safety zone could be subjected to.
 

Grumpy Git

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If the entire nose cone was destroyed at 15mph, that means a dead driver at higher speed collisions. Not great. What's the maximum speed collision possible on the ECML?

I don't think you understand. The nose cone is nothing more than a lightweight fairing made out of the composite equivalent of Papier-mâché. It is not designed to handle any hard impact force, (like a set of buffers for instance).
 

Swimbar

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I don't think you understand. The nose cone is nothing more than a lightweight fairing made out of the composite equivalent of Papier-mâché. It is not designed to handle any hard impact force, (like a set of buffers for instance).

I think we all accept that the cab of both trains was going to damaged and that some of the damage looks worse than it probably is.
However many of us did not expect the 800 to react like it did further down the set and derail.
Will have to wait for the RAIB report.
 

43066

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If the entire nose cone was destroyed at 15mph, that means a dead driver at higher speed collisions. Not great. What's the maximum speed collision possible on the ECML?

250mph?

A dead driver is a certainty at high speed collisions.
 

ainsworth74

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If the entire nose cone was destroyed at 15mph, that means a dead driver at higher speed collisions. Not great. What's the maximum speed collision possible on the ECML?

Yes it was. Good job the driver was in the cab and not the nose cone I guess.
 

ManOnATrain

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I don't think you understand. The nose cone is nothing more than a lightweight fairing made out of the composite equivalent of Papier-mâché. It is not designed to handle any hard impact force, (like a set of buffers for instance).


Well if I don't understand then tell me what collision speed guarantees a driver being alive after a coliision
 

ManOnATrain

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250mph?

A dead driver is a certainty at high speed collisions.

Not possible, maximum line speed 125mph. If the line is speed is that max then going any higher surely risks derailment.
 

M7R

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Not possible, maximum line speed 125mph. If the line is speed is that max then going any higher surely risks derailment.

I believe he means 125mph into another 125mph in the opposite direction so 250mph closing speed
 

Swimbar

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125mph, crashing into something coming 125mph the other way. Impact speed = 250mph.

It derails, albeit across a set of points, on an impact speed of 9 mph.
One does wonder of all the computer collison simulations were done on the basis of a straight line impact and nobody though about impacts involving the set straddling a set of points!
 

swt_passenger

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Reminds me, wasn’t a 450 derailed sideways in a buffer stop collision in Waterloo station, from a standing start in the platform? That was effectively straight track. Can’t find a RAIB report.
 

43066

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Not possible, maximum line speed 125mph. If the line is speed is that max then going any higher surely risks derailment.

I believe he means 125mph into another 125mph in the opposite direction so 250mph closing speed

What about another train coming the other way?

125mph, crashing into something coming 125mph the other way. Impact speed = 250mph.

Yep!

Not to darken the thread, but a fatality encountered at higher line speeds (ie the mere weight of a human body versus hundreds of tons of fast moving metal) often results in significant damage, and the afflicted unit/loco being taken out of service for repairs.

Two trains colliding head on (hundreds of tons versus hundreds of tons) simply doesn’t bear thinking about.

Luckily TPWS etc. generally prevents such occurrences these days.
 
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Pete_uk

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I'm guessing any crumple zones on the connecting rods or whatever will only crumple over a certain speed?
 

hwl

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I think we all accept that the cab of both trains was going to damaged and that some of the damage looks worse than it probably is.
However many of us did not expect the 800 to react like it did further down the set and derail.
Will have to wait for the RAIB report.
The 800 cab (see above drawing) didn't get damaged the nose cone did.
 

hwl

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I'm guessing any crumple zones on the connecting rods or whatever will only crumple over a certain speed?
Correct the lead coupling and the 2 impact absorption boxes shown in the image above are only meant to start collapsing at speeds above those in this case.
 

hwl

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Well if I don't understand then tell me what collision speed guarantees a driver being alive after a coliision
The instructior in the second mans seat in the 66 at Great Heck survived a closing speed impact at 142mph on his side of the cab.
 

Raul_Duke

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Well if I don't understand then tell me what collision speed guarantees a driver being alive after a coliision

What speed of car crash guarantees survivability? There isn’t one due to a multitude of contributing factors. The only general rule is slower = more survivable usually.
 

TheEdge

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The instructior in the second mans seat in the 66 at Great Heck survived a closing speed impact at 142mph on his side of the cab.

There always is a certain amount of luck. Look at seat maps of air crashes and you see a whole row died with a single survivor who somehow got away with it.

But at crashes at that speed there is a limit to what can be engineered to protect the driver and then a mix of luck and the laws of physics take the reigns
 

Mathew S

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Well if I don't understand then tell me what collision speed guarantees a driver being alive after a coliision
That's not how collisions work. While the macro-scale forces are predictable, there are so many thousands of variables, from the speed, to the exact angle of collision, to the height, weight, and level of fitness of the driver that nothing can ever be certain.
People have died in <20 mph car accidents and survived ones that happened at well over 100 mph, which shows just how seemingly random it can be.
There are no guarantees but, from a safety point of view, give me a new train that's passed modern crash-worthiness standards over an HST any day; the risk is so, so much lower.
 
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