On Sat, 26 Apr 2003 14:57:26 +0100, Daniel Barlow <
[email protected]> wrote:
>[ Hope I've got the attributions right here ]
>Paul Smith <
[email protected]> writes:
>> Gonzalez <
[email protected]> wrote:
>>>And all things being equal, slower speeds are safer speeds.
>> All things can never be equal. Somehow the speed was changed, and not by magic or theory. Anyway
>> the other part isn't true either. Imagine trying to do a "nice safe 30mph" in lane 3 of a busy
>> motorway. Many researchers have found a U shaped curve of accident risk with the fastest and
>> slowest drivers at elevated risk of accident.
>With the exception of very large vehicles, the speed limits are the same for everyone. Nobody is
>forcing these slower vehicles to travel more slowly; the strong probability is that they're going
>as fast as they judge to be safe (perhaps they're not confident drivers, or they don't know the
>road, or they just have poor judgement). I don't think you can claim these accidents as due to
>inattention.
The time that inattention is likely to arise is if we cause people to drive at a speed which they
properly judge to be well under the speed they would otherwise have properly chosen. There's quite a
bit of it about.
>>>>>> lower speed (of cycling) is inherently less demanding
>Were all other thing equal, I'd agree, but as you point out, they can never be.
Accepted.
>For one thing, the cognitive load is probably mostly a function of _perceived_ speed.
I dispute that. It's a function of "time to react". When travelling near or above maximum safe
limits there's a dramatic and obvious increase in workload and concentration, as one strives to take
account of all that's happening. At such speeds; (which I never recommend for road driving by the
way) One might have a sensation of being "on the edge" and concentration is critical.
Below this potential "ragged edge" there's a sliding scale and as speed tends towards zero, so does
the requirement to concentrate.
> In a car at 25mph, the suspension filters out vibration from the road surface, the enclosed body
> filter out wind noise, the mass of the car ensures that crosswind is not really an issue and the
> momentum of the car tends to mean that minor gradients are not nearly as obvious. On top of which,
> I'm not actually _doing_ very much. On a bike at the same speed, I have skinny tyres that transmit
> every bump from the road, I'm being buffeted by the wind and by the draft from passing vehicles,
> every change in gradient gets noticed, and I'm busy turning my legs around at 90+ rpm. I don't
> think the situations are comparable, let alone equal.
I don't think the factors you cite have much to do with the sort of concentration we were talking
about. I was talking about directing concentration towards developing events ahead. In the case
of what might be termed "concentrated cycling" it isn't unusual to see racing cyclists looking
down while they concentrate on delivering maximum output. Are these guys paying attention to the
road ahead?
>>> Do you think a driver could do the trip safely in their Ferrari in 1.5 hours at 160 mph?
>> Sometimes, in certain circumstances, yes, I do think so. It might be possible to find a quiet
>> autobahn, or maybe we could do it at a test track. There's no inherent danger in speed. The
>> danger only arises when the speed is inappropriate for the conditions.
>A jet pilot could probably do the trip pretty safely at 300mph in something less than an hour, if
>not on the same (or any) road. I don't think these examples are adding anything.
Agreed.
--
Paul Smith Scotland, UK
http://www.safespeed.org.uk please remove "XYZ" to reply by email speed
cameras cost lives
