Safe Speed Forums

Firstly apologies for being a late entrant into this thread - I have been heavily involved in the election that we had in Australia 2 weeks ago (and the results are not yet final!!!!!!! )

DCBW has quoted the NSW Roads and Traffic Authority as one of his sources. They in turn are quoting a study done by CASR at the University of Adelaide. I have read this study in detail and find it seriously faulty in its execution and interpretation. It is so bad that if I had done it as a school project I would have got, and deserved, six of the very best!

Note that since the original was written and following criticism (by myself and others) the methodology has been re-written - without repeating the work!

For those who may have forgotten, my professional expertise is in the assessment of Industrial Research and Development projects from the technological, financial, management ability and commercial prospects. This was for the Australian Government's Ausindustry Grants and Taxation Programmes.

For Weepy and DCBW's information the 85% finding was from very extensive work done by Solomon and others in about 1964. (In the USA) This work has been repeated by others using different methodology and produced the same result ie the probability of having a crash is at a minimum when the travelling speed is at the 85th per centile free speed ie unfettered by traffic, enforcement or artificial limits. Drivers at lower speeds may be drunk, incompetent etc, those at higher speeds may be drunk or driving beyond their capabilities etc.

A speed limit therefore should be tailored to get as many as possible travelling at the observed 85% speed with enforcement targetted at those significantly above this.

Australian road safety research is conducted at several Universities. Unfortunately they are not rivals but incestuous; they "Peer Review" each others work and I have never seen any real criticism.

(Peer review is like the little girl with a curl; when it is good it is very good but when it is bad it is truly horrid. The best review is done by rivals or sceptics - that is how the problems are found)

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The only thing that should be prohibited is prohibition.

I can find a lot of references on the net to the Solomon/Cirillo paper but not the original work. Do you, perchance, have a link? But I would be some what dubious of applying 50 year old research in a country with very different driving mores to 21st century UK.



Again I am having great difficulty finding this research. And how does one establish a speed "unfettered by traffic" on present day crowded roads?

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When I see an adult on a bicycle, I do not despair for the future of the human race. H.G. Wells
When I see a youth in a motor car I do d.c.brown

Do a traffic survey off peak? Just a thought...

I'd be interested to see your analysis of that study, just to see whether it tallies with mine.

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Only when ideology, prejudice and dogma are set aside does the truth emerge - Kepler

But MPL actually said "unfettered by traffic, enforcement or artificial limits." So I should really have asked how do you do a survey unfettered by artificial limits in a country with a NSL?

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When I see an adult on a bicycle, I do not despair for the future of the human race. H.G. Wells
When I see a youth in a motor car I do d.c.brown

I'D have thought that even to a graduate that even this was possible ( DO IT AT NIGHT, dear whaley , at night) ( and I won't post what the spell checker says about YOUR NAME)

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lets bring sanity back to speed limits.
Drivers are like donkeys -they respond best to a carrot, not a stick .Road safety experts are like Asses - best kept covered up ,or sat on

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At night you would still be "fettered by an artificial limit". And by doing at night you would get a very skewed sample of drivers.


"No spelling suggestion" is what Office 2003 says about dcbwhaley. But what it suggests for Botach is very appropriate

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When I see an adult on a bicycle, I do not despair for the future of the human race. H.G. Wells
When I see a youth in a motor car I do d.c.brown

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The world runs on oil, period. No other substance can compete when it comes to energy density, flexibility, ease of handling, ease of transportation. If oil didn’t exist we would have to invent it.”

56 years after it was decided it was needed, the Bedford Bypass is nearing completion. The last single carriageway length of it.We have the most photogenic mayor though, always being photographed doing nothing

Thank you, jomo but those links merely assert the 85th percentile without presenting or referencing any raw data. The first graph in the first link shows that the accident rate is asymptomatic to infinity as the speed falls, which would be obvious nonsense and cast doubt on the rest of the curve. Am I missing something?

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When I see an adult on a bicycle, I do not despair for the future of the human race. H.G. Wells
When I see a youth in a motor car I do d.c.brown

Also, are the figures mutually exclusive?

I.e. is the crash rate for the fastest and slowest drivers intertwined because the faster drivers are crashing into the slower drivers?

Which would obviously be the fast drivers fault every single time, eh weeps?

Extending strict liability I'd say yes, the faster driver should be able to show there was no way of avoiding the collision, and that would include slowing down (presuming the slower driving is not breaking any rules or laws).

So if no one was breaking any rules or laws, in what scenario can you see an accident happening, whereby a faster driver collides with a slower driver?

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My views do not represent Safespeed but those of a driver who has driven for 39 yrs, in all conditions, at all times of the day & night on every type of road and covered well over a million miles, so knows a bit about what makes for safety on the road,what is really dangerous and needs to be observed when driving and quite frankly, the speedo is way down on my list of things to observe to negotiate Britain's roads safely, but I don't expect some fool who sits behind a desk all day to appreciate that.

Plenty!

Good!, then you have NO trouble giving just ONE example then?

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My views do not represent Safespeed but those of a driver who has driven for 39 yrs, in all conditions, at all times of the day & night on every type of road and covered well over a million miles, so knows a bit about what makes for safety on the road,what is really dangerous and needs to be observed when driving and quite frankly, the speedo is way down on my list of things to observe to negotiate Britain's roads safely, but I don't expect some fool who sits behind a desk all day to appreciate that.

Yes you are. The Y-axis units are: "Involvement Rate per 100 Million Vehicle-Miles", so it would tend to infinity at zero speed - the same way as would a graph of journey time vs speed, or fuel consumption vs speed.

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Only when ideology, prejudice and dogma are set aside does the truth emerge - Kepler

I was assuming that the accident rate of a stationary vehicle would be zero. But, on reflection, that isn't true. Someone could run into a stationary vehicle on the road. And even in the garage someone could bang their head on the open tailgate

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When I see an adult on a bicycle, I do not despair for the future of the human race. H.G. Wells
When I see a youth in a motor car I do d.c.brown

I can think of one: when someone turns out right in front of you, and then, instead of accelerating as you might reasonably expect them to, promptly stops. You don't stand a chance.
But, in weepej's world, it would be your fault.

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Only when ideology, prejudice and dogma are set aside does the truth emerge - Kepler

Can you remind me what "strict liabilty" was? Was that the thing about setting aside the actual evidence and going for predetermined definitions of who was the most guilty in each situation?

Yes but the slower driver was then driving without due care and attention and Weppej said, that if the slower driver WASN'T breaking rules or laws, so I cannot see any situation whereby this would happen.

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My views do not represent Safespeed but those of a driver who has driven for 39 yrs, in all conditions, at all times of the day & night on every type of road and covered well over a million miles, so knows a bit about what makes for safety on the road,what is really dangerous and needs to be observed when driving and quite frankly, the speedo is way down on my list of things to observe to negotiate Britain's roads safely, but I don't expect some fool who sits behind a desk all day to appreciate that.