"Paul Smith" <
[email protected]> wrote
> "DR" <
[email protected]> wrote:
>
> >> >Why do you keep repeating the false assertion that 5% comes from the pre-incident CE (sic).
>
> >Yesterday he tried telling me it was 0.5%.
>
> I can put it between 0.5% and 5% (I think) on average at present.
>
> >> Because it's clear from the tiny percentages who die that on average only a small percentage of
> >> the previous energy ends up in the crash.
>
> >The idea obviously hasn't sunk in yet that a vehicle can suffer damage while keeping acceleration
> >below a threshold for serious injury. If you examine footage of racing car crashes it might give
> >a clue.
>
> I've got 400 sample accident reports, and I'm trying to factor such things in. One field is
> "number of impacts", which is helpful. Most are a single impact.
I don't doubt that "most are a single impact". I don't think that is the issue. I take issue with is
your assessment of of KE absorbed in impact.
We know racing accidents deliver 100% of the KE to damage to the car and track from speeds typically
greater than road accidents. I know from personal experience that 10 people survived without injury
when about 30% of pre-event KE was delivered (at a guess 35mph impact after braking from 60mph).
You might be right if 0.5% of energy was delivered to a pedestrian or cyclist, but I don't have a
figure for the absorbency of human flesh. With a mass difference of at least 12:1 the impact itself
does not slow a vehicle significantly.
Quite clearly, what you hit is the important consideration. In that link to French data I gave you a
couple of weeks ago, one of the entries was that about 6% of casualties hit a tree. I don't know but
my guess is that people don't see an "unexpected" tree and try to brake to avoid. They go into a
tree because they lost control.
David Roberts