On Mon, 14 Apr 2008 10:34:24 +0100, "Doki" <[email hidden]> said
in <[email hidden]>:
Quoted message said:What was the gist? I thought I saw some govt figures in the papers a while
back which disproved the 1/3 of accidents caused by speeding claim. The
leading cause IIRC was inattention.
Two separate issues. This was Smith's hilarious "one in three
fatalities caused by cameras" argument.
One problem with trying to work out how many deaths are "caused" by
speed, is that the answer is always going to be somewhere between 0%
and 100% depending on how you define cause. For example, falling
asleep at the wheel of a car moving at 3mph is markedly less likely
to cause death than doing the same at 40mph, sop a death caused by
falling asleep at the wheel at 40mph has, as a contributory
causative factor, speed.
Another is that the records of cause used to claim "x% of fatalities
are caused by speed" are largely subjective. Plod at the scene may
record "driver lost control" - this almost always means excess
speed. And if speed above the limit is not recorded, it may simply
be because loss of control will do, and there is not sufficient
evidence to state with confidence that the driver was above the
limit, even if it is highly likely. The reports are intended to
deal with provable certainties, their collection methods change
fairly often, and extrapolating these to population-level statistics
is not terribly robust.
The indisputable fact is, if everybody drove more slowly, fewer
people would die. The evidence that both incidence and severity of
collisions rises with speed on a given class of road seems to me to
be pretty solid. The only figures which contradict this, as far as I
can tell, are from areas where compliance was low, so raising a
limit actually reduced the mean speed due to increased compliance,
and misinterpretation of the risk of turning manoeuvres as being in
some way due to low speed.
Slower is less dangerous, but of course also /slower/, so we have a
speed limit as a balance between personal utility and public danger,
which is fine by me. I don't think there is anyone still driving
who passed a test before speed limits were a part of the road
traffic law, it's not like it comes as a surprise or anything.
The major problem with Smith and his ilk, in my view, is that their
fixation on "proving" that enforcing the speed limit is evil, is
founded in the belief that it is perfectly safe for /them/ (being in
the 85% of drivers whose skill is above average) to drive as fast as
they damn well please. I guess this much is obvious. I refer to it
as the "speed imperative" - they are unwilling to concede that going
more slowly is an acceptable option.
Trying to work out precisely how many collisions have, as a
causative factor, speed in excess of the limit, is akin to arguing
over how many angels can dance on the head of a pin: driving within
the limit is, in pretty much every case, going to be less risky than
driving in excess of it. Smith's 12mph comedy web page is a perfect
illustration of their [censored]-about reasoning: any reasonable person
would look at the figure of 12mph and question the mechanism by
which a 12mph collision could cause fatality. Smith, instead,
tortures statistics to within an inch of their lives in order to
assert a point which any reasonable person would simply dismiss as
foolish, since in the absence of a credible mechanism by which such
collisions could cause meaningful numbers of deaths, no rational
debate can be had about the level of fatalities if speeds were
hypothetically reduced to 12mph.
This is the key point of denial for the Smithites. Hit a pedestrian
at 40mph, you'll probably kill them. Hit them at 30mph and you
probably won't. If you hit them at all, of course - if two drivers
perceive a hazard at the same time, and one is doing 30 and one 40,
and both react and brake at the speeds in the Highway Code, then the
40mph driver will still be doing 30 when the 30mph driver stops.
Newtonian mechanics (invented by Robert Hooke, but I digress) is
simplistic but also very robust. You can argue about where it
happens and how, but there /will/ be a point at which the slower
driver stops while the faster driver is still moving.
I don't think mechanistic enforcement of laws solves the problem of
excess risk taking and the manifestly false perception these people
have of the risk they pose (see how often they claim something is
"perfectly safe" or even just "safe" without any attempt to quantify
the actual risk), but if it causes them to drive more slowly it at
least minimises the risk they pose to others.
When they passed their tests, they were expected to understand what
the law is, and the license is granted on the understanding that the
law will be obeyed or the license may be withdrawn. This has been
the case for as long as I can remember and probably longer. "Oh, but
I thought you would not enforce it!" has never been a defence in
law.
Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk
85% of helmet statistics are made up, 69% of them at CHS, Puget Sound
