Matt B wrote:
> "David Martin" <[email protected]> wrote in message
> news:[email protected]...
> >
> > Matt B wrote:
> >
> >> Not at all. I'm simply hilighting the randomness of the selection of the
> >> "critical" limit. It is not scientific - what are the chances it would
> >> be
> >> _exactly_ 30 mph? It is "plucked out of the air" as a round number in
> >> the
> >> units which happened to be in favour in the 1930's.
> >
> >> Note in Ireland when they changed to metric on the roads the safe urban
> >> speed limit also changed (it went up from 30 mph to 31.07 mph, that's how
> >> sacrsanct they are! Why is ours not 19 or 28 mph, or eve 31.07 mph?
> >
> > It is a straw man.
>
> It is not.
>
> > There are a limited set of speed limits that can
> > legally be set.
>
> Now that _is_ a strawman. We all know the only reason is because that is
> how our legislators have set it, not for any intrinsic "good" reason.
You presuppose that there is no reasoning behind the law. That would be
a fallacy.
> > (IIRC 20mph is not one of them, or until recently
> > wasn't so cannot be enforced, merely reccommended). To set an
> > accurate[1] speed limit would not only require a change in the law [2]
>
> 1000's of changes are made every year, so that's no obstacle.
> > but would require speed limits being set at strage values very
> > frequently, ie for every bend, straight, field entrance and so on.
>
> Why? Who needs limits? Where _exactly_ is 30 precisely correct? Do you
> not think that motorists adust their speed other than to each posted limit
> as they encounter it - sheesh.
Which is somehow not as good as motorists driving as fast as they think
they can get away with? why precisely?
> > It is safer to not over tax the motorists' brain cell[3] by confusing
> > them with lots of slightly variable limits,
>
> Who's asking for variable limits? Does the technology exist to set them
> appropriately for each vehicle/driver, for every second of every journey, in
> all lighting, weather, traffic and all other environmental conditions?
Wrong term. Try non-standardised limits.
>
> > but instead to give them a
> > set which correspond nicely with the major markings on their speedo.
>
> The only reason drivers need speedos is because of speed limits.
Ignoring the psychological effects of becoming used to faster speeds,
whilst in a box that is advertised as being very good at isolating you
from your surroundings. Replace objective assessment with subjective
assessment. Fantastic idea .. not!
> > So
> > 30mph is not the accurate (see [1]) safe ([1] also applies) limit?
>
> Why not, rather than a "30" put a picture of houses, or people, or whatever,
> to indicate a build-up area, then expect due diligence?
Because it doesn't work. Motorists would overestimate their ability,
underestimate the danger and inconvenience they pose, and prosecuting
the not particularly dilligent would be very hard. There would be no
penalty for getting away with not paying due dilligence.
> > The
> > next available is 40mph which is tantamount to no limit at all in a
> > built up area.
> Sheesh.
>
> > We need speed limits because motorists are unable to appropriately
> > regulate their speed where it matters most [5].
>
> Look around. Does everyone drive at precisely 30 mph at all times within
> the 30 mph limit? Your assertion requires the answer to be "yes".
Your logic seems flawed. Why does providing a maximum also imply a
minimum? (it doesn't). It is perfectly possible for a safe and
competent driver to choose to drive well below the posted speed limit,
where that limit is too high for the circumstances.
As it is, most motorists will drive at the limit (approximately), not
becasue the limit itself is to high but their perception of what is an
appropriate speed for the conditions is too high.
> > The current mechanism
> > may not be as finegrained as one might like in terms of
> > application but it is comprehensible and workable.
>
> So there are no road "accidents" in built-up areas in the entire country -
> ever? If there in fact is one, even occaisionally, I would suggest that
> speed limits don't work.
In order to support that outlandish assertion, you would have to argue
that all accidents are solely the cause of travelling at speeds above
the posted limit. That is clearly not the case. What one can clearly
show is that risk is related to speed, and that providing a cap on
speed places a cap on risk. Slowing speeds from 35 to 30 in built up
areas (ie to the limit rather than +10%+2) resulted in a dramatic
reduction in accidents in tests of speed limiters in Sweden.
Reducing speeds reduces accidents. It doesn't remove all accidents, but
no-one claimed it did.
Your argument is a bit like the fallacy of generalisation.
'My cat is black'
'Your cat can't be black becasue not all cats are black'
...d
