On Thu, 30 Oct 2003 16:07:42 GMT, "Richard J."
wrote:

But the front of the derailed car at Camden Town was destroyed rather than
crumpled. Photo at http://news.bbc.co.uk/1/hi/england/london/3227365.stm
This may have been because it hit the wall at an angle rather than head-on.

Probably. One of the fundamental weaknesses of a metal tube of any
kind (or indeed a bog roll tube if you want to try it out yourself!)
is that, while it can take a massive end loading without buckling, a
small side loading is sufficient to cause major deformation. Without
returning to compartment stock (obviously not practicable on the
Tube), this will always be the case regardless of strengthening.

How the Mark 3 and aluminium Turbo stock performed (or did not) in
recent HST crashes is a good comparison. Compress the HST stock
end-on and it's fine. If one vehicle jack-knifes, it'll likely end up
in a far worse way.

The other issues, of course, are that Tube trains travel much more
slowly - and in the majority of cases (e.g. Chancery Lane) will stay
in line simply by virtue of the fact that the tunnel is but a few
inches away on each side, so collisions at an odd angle are rare.
This must surely impact on the design.

Neil

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