antera309 wrote:
Cruise control aside, anyone who drives a car will know how difficult it is to stay at a constant speed, even in the absence of any other traffic. Hills, bends, wind and tiny differences in pressure exerted on the accelerator pedal all act to vary your speed constantly. Unless you are constantly checking your speedo, this happens without your knowledge. No conscious "decision" is being taken to drive faster/slower.
In reality, a driver should be allowed a +/-8mph "tolerance" in their speed to allow for these variations. Unrealistic speed limits, combined with excessive enforcement are denying them this.
Take the example of a rural road, with a camera enforced 30mph limit (implemented due to non-speed related accidents or purely as a "traffic calming" measure)....
Drive below 30mph, and you start annoying the drivers behind, who often then get too close and you risk being rear-ended if you have to brake for whatever reason.
Drive above 34mph and you are risking your licence.
That's a tolerance of +/- 4mph, which is not even enough to allow for the laws of physics, let alone varying one's speed according to the conditions
I've been shot down for this before, but I will say it again anyway (lets face it, I wouldn't be here still if I got offended easily!)
There are more interfaces in the vehicle - human system than the speedo. There is the noise - both engine and road. There is the vibration through the entire contact area of the seat. There are visual clues outside the window. There is even an inate human sense of stability (the same one that tells you when your plane starts to turn, long before you have any visual clues through the window) and of course there is the absolute indicator, the speedo.
All of the above should be operating in 'the system'. I would not expect anyone to be able to deduce absolute speed from any of the non absolute indicators, but I maintain that you should be able to deduce a deviation or change. 4mph at 30 is more than a 10% change, unless the rate of change is slow (by definition - an imperceptable rate of change) then this should be sensed by the human in the system. If the rate IS so slow, then surely at some point in the extended time the human will have referred to the speedo as part of the standard operational cycle?
As to driving at 10% below the limit (temporarily rather than consistently) I don't have the same issues with this.
Andy
p.s. I used to say - prior to joining this site - that "I never speed". I now recognise that I am merely human and now I say "When driving, at ALL times I make the best possible efforts I can to keep my speed inside the posted limit". It's not a huge difference, but an important one to me.
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