On Fri, 7 Dec 2007 21:29:38 -0000, Adam Lea <
[email protected]> wrote:
>
> "Ian Smith" <[email protected]> wrote in message
> news:[email protected]...
> > On Fri, 7 Dec 2007, Nigel Cliffe <[email protected]> wrote:
> >
> >> Just removing, at most, a few thousand drivers per year (even
> >> all those involved in fatalities) from the roads will make no
> >> noticable difference to road safety.
> >
> > Is this just proof by assertion, or do you have some justification
> > for that view?
>
> It depends on what the ratio of driving errors that result in
> injury/death to the total number of driving errors is. Assuming
> that any one driving error has a finite chance of resulting in an
> injury or worse then if that ratio is very small then removing a
> few thousand drivers won't reduce the number of total driving
> errors significantly enough to affect the overall probability of
> injury/death.
You are apparently assuming that there is a near-constant number of
driving errors per driver. There is plenty of evidence that this is
not the case - some drivers make many more errors than others. If
there is a near-constant probability per error but a given driver has
hundreds of times more errors than average, then taking that one driver
off the road will be disproportionately beneficial.
There is good evidence that drivers that routinely ignore speed limits
have disproportionately more accidents, for example.
In which case, taking a few thousand such drivers off the roads would
be equivalent to taking a few hundreds of thousands of average drivers
off. That could easily be noticeable.
Plus, that's assuming that the action of removing the drivers does not
influence the behaviour of those remaining - it's at least reasonably
plausible that such a policy could increase the care taken by those
that remain.
regards, Ian SMith
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