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

Discussion in 'UK Railway Discussion' started by Class455, 13 Nov 2019.

  1. sprinterguy

    sprinterguy Established Member

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    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.
     
    Last edited: 27 Nov 2019
  2. Bantamzen

    Bantamzen Established Member

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    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.
     
  3. 800002

    800002 Member

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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?
     
  4. hwl

    hwl Established Member

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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...


    upload_2019-11-27_16-46-28.png
     
    Last edited: 27 Nov 2019
  5. RealTrains07

    RealTrains07 On Moderation

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

    Raul_Duke Member

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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.
     
  7. 43066

    43066 Member

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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
     
  8. D6700

    D6700 Member

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    813109, which would be the third vehicle. Cracked gear box, I've heard.
     
  9. ComUtoR

    ComUtoR Established Member

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

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

    ManOnATrain Member

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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?
     
  11. daikilo

    daikilo Established Member

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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.
     
  12. Grumpy Git

    Grumpy Git Member

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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).
     
  13. Swimbar

    Swimbar Member

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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.
     
  14. 43066

    43066 Member

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    250mph?

    A dead driver is a certainty at high speed collisions.
     
  15. ainsworth74

    ainsworth74 Forum Staff Staff Member Global Moderator

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

    ManOnATrain Member

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

    ManOnATrain Member

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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.
     
  18. M7R

    M7R Member

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

    swt_passenger Veteran Member

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    What about another train coming the other way?
     
  20. Bungle

    Bungle Member

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

    Swimbar Member

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    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!
     
  22. swt_passenger

    swt_passenger Veteran Member

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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.
     
  23. 43066

    43066 Member

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    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.
     
    Last edited: 28 Nov 2019
  24. Pete_uk

    Pete_uk Member

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

    hwl Established Member

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    The 800 cab (see above drawing) didn't get damaged the nose cone did.
     
  26. hwl

    hwl Established Member

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    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.
     
  27. hwl

    hwl Established Member

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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.
     
  28. Raul_Duke

    Raul_Duke Member

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    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.
     
  29. TheEdge

    TheEdge Established Member

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    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
     
  30. Mathew S

    Mathew S Established Member

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    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.
     
    Last edited: 28 Nov 2019

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