20mph limits..useful by schools or spawn of Satan?

[jaydee]

I'd see limit enforcement as a useful adjunct to, but not, as the government etc. seem to believe, a replacement for, good driver education.

To an extent you can educate out risk taking behaviours but there may be risk factors that cannot be readily observed by traffic in certain areas, and in these areas speed limiting and enforcement may be justified.

One example opf this being a crossroads where the traffic is unsighted by the geography, I can think of a local example to me where accidents have been a regular phenomenom and have, sadly, excessive speed as the primary factor but, needless to say, this is nsl despite there being a lengthy (and inexplicable) stretch of 40mph limit further down the same road.

Edit. 'Coz I pressed the wrong button :

A need remains to limit the speeds achieved in some areas by those who lack the ability or sense to moderate their speeds but this should be accompanied by a move to increase the abilities of new and more experienced drivers alike.

Speed is seldom the sole factor in any incident. Unfortunately it is the factor most readily mitigated against and produces measurable results in terms of detection of offences - something which is very hard to achieve with other methods of alledged accident reduction.



>> Edited by jaydee on Saturday 2nd August 15:53

[safespeed]

jaydee said:

I'd see limit enforcement as a useful adjunct to, but not, as the government etc. seem to believe, a replacement for, good driver education.

Intelligent speed limit enforcement is fine by me. Dumb automated enforcement, and speed limit enforcement as a proxy for enforcement against dangerous behaviours, are not.

Don't forget we already have the safest roads in the world and what we need to do is nudge the system in the direction of improved safety. Presently we appear to be achieving the exact opposite.

Best Regards,
Paul Smith
Safe Speed
www.safespeed.org.uk

[safespeed]

jaydee said:

Speed is seldom the sole factor in any incident. Unfortunately it is the factor most readily mitigated against and produces measurable results in terms of detection of offences - something which is very hard to achieve with other methods of alledged accident reduction.

I've yet to see any credible evidence that dumb speed limit enforcement has contributed to accident reduction. National figures appear to indicate the exact opposite. See:

www.safespeed.org.uk/fatality.html

Over 5,000 extra road deaths to date and no explanation other than bad policy that I can find.

Best Regards,
Paul Smith
Safe Speed
www.safespeed.org.uk

[jaydee]

Well, that's an afternoon spent chewing over the arguments pertaining to an issue on which we are, broadly, in agreement.

We don't have the lowest accident, injury or death figures in the world sadly (source FIA). Denmark and the Netherlands both have lower aggregated figures. Germany has an odd situation of far lower figures than most of Europe (UK included) if one takes out deaths attributed to DUI.

[safespeed]

jaydee said:

Well, that's an afternoon spent chewing over the arguments pertaining to an issue on which we are, broadly, in agreement. We don't have the lowest accident, injury or death figures in the world sadly (source FIA). Denmark and the Netherlands both have lower aggregated figures. Germany has an odd situation of far lower figures than most of Europe (UK included) if one takes out deaths attributed to DUI.

We have the lowest "risk factors" according to the International Road Traffic Accident Database (IRTAD). I regard IRTAD as the highest authority.

www.bast.de/htdocs/fachthemen/irtad//index.htm

I'm happy to have spent some time on this, anyway, it's reasonable fun for a boring git like me

Best Regards
Paul Smith
Safe Speed
www.safespeed.org.uk

[jaydee]

safespeed said:

jaydee said: Speed is seldom the sole factor in any incident. Unfortunately it is the factor most readily mitigated against and produces measurable results in terms of detection of offences - something which is very hard to achieve with other methods of alledged accident reduction. I've yet to see any credible evidence that dumb speed limit enforcement has contributed to accident reduction. National figures appear to indicate the exact opposite.

That wasn't what I said. Speed is a demonstrable factor in some accidents and is that factor most readily mitigated against through enforcement and legislation. Provided the figures can be spun as providing an increase in safety and the propagation of 'safety' cameras be self funding it is an area of enforcement that is very appealing, remembering the politicians' viewpoint that it is not to do something, it is, rather, to be seen to be doing something.

I'm afraid I find the page you direct to a little disingenuous. The extraction of the figures you have chosen to take disregards the likelihood of regression to the mean. By isolating a two year period it can be suggested that the drop in fatalities has been only .42% as against a historical precedent of an annual drop of 5.26%. However, a closer inspection of the figures reveals that there have been increases in the annual fatality rates (ie -ve %age changes) at numerous points. If taken in isolation these would suggest a trend towards an increase in deaths, where the reality is a mean decrease.

Since the '50s there has been exponential diminution in accident rates despite an exponential rise in the number of vehicles on the roads. As a proportion of fatal accidents are, we can assume, unavoidable then an exponential reduction is what one would expect, with a long term regression to the mean (ie. an average reduction of 5.26% pa)

There isn't anything in the TSGB stats* to support the contention that "Something happened in about 1993 to badly damage the long term downward trend in British road fatalities. The changes are very significant. In fact if we'd followed the yellow trend line 3,657 people who have died would still have been alive at the end of 2001. The extra lives lost in 2002 (figures not yet available) will be well over a thousand."

*You're correct BTW, they do seem to have disappeared from the government sites. Luckily I've got the paper copies on my desk

>> Edited by jaydee on Saturday 2nd August 16:25

[jaydee]

safespeed said:

We have the lowest "risk factors" according to the International Road Traffic Accident Database (IRTAD). I regard IRTAD as the highest authority.

I wouldn't. IRTAD derives non-equivalent data for its figures. Fatality information is not gathered in an equivalent manner throughout the world, nor are the figures from the same period throughout. The model of fatality data collection in continental Europe and the US (I don't have data for the RotW) differs from that in the UK. UK data is of fatality at the time of accident whereas that from most other EU countries and the US is to record fatalities at the accident scene as RTA related deaths as well as those which arise after the fact as a result of injuries received. To make it onto the deaths list in the UK you need to be dead at the scene or DOA.

safespeed said:

I'm happy to have spent some time on this, anyway, it's reasonable fun for a boring git like me

Me too I do 'safety' for a living deriving biometric data from crash tests and real impacts and also giving the 'don't play on the roads' (aka: lets make the nice policemen ) spiel to a range of professional drivers.

>> Edited for idiocy re:smilies and formatting, content unchanged.

>> Edited by jaydee on Saturday 2nd August 16:39

[hertsbiker]

Safe speed, how about some rigorous enforcement of "Primary Pedestrian Safety" where kids in particular are taught the Green Cross code, and adults don't get pissed up & fall in front of cars.

Why is is always the car drivers "fault" ?

And tell me why in 1926 we had a tenth or twentyth of the number of cars, but more roads deaths than we do now?

Could all this "Speed kills" issue be a load of b*ll*cks? howabout people taking responsibility for their actions as Pedestrians, not just motor users? perhaps if the namby-pamby way we bring kids up these days is the root cause of so many accidents. Certainly many kids my way are lippy little urchins who will deliberately step in your way to prove a point.

cheers, Carl (mad as hell with the lentilista attitude, and my website would be called www.IpayfortheroadsoImgonnauseit.com )

[safespeed]

jaydee said:

I'm afraid I find the page you direct to a little disingenuous. The extraction of the figures you have chosen to take disregards the likelihood of regression to the mean. By isolating a two year period it can be suggested that the drop in fatalities has been only .42% as against a historical precedent of an annual drop of 5.26%. However, a closer inspection of the figures reveals that there have been increases in the annual fatality rates (ie -ve %age changes) at numerous points. If taken in isolation these would suggest a trend towards an increase in deaths, where the reality is a mean decrease.

Then I think you need to examine the figures again. I've looked at the GB fatality rate forwards, backwards, upside down and sideways. I've fitted a zillion curves and equations.

Whatever way you look at it, there's a substantial deviation from the long established trend which starts in 1993/1994. This is no two year glitch. This is a change established for a decade. Neither has it got ANYTHING to do with "regression to the mean" - what mean would that be then?

Over the period 1978 until 1993 the average reduction in fatality rate was 6.81% per annum. Through the later 90s until 2001 this reate declined progressively to zero in 2001. We appear to have a 3% gain in 2002 from provisional figures, (which would be half what we ought to expect, and in any event may well be a glitch.)

If you doubt trend changes in 1993/4 have a look at a range of graphs on:
www.safespeed.org.uk/stats/graphs.html
...many of which have a 1993 kink.

Download the spreadsheet and have a look. There's nothing "disingenuous" there. You have my word.

Best Regards,
Paul Smith
Safe Speed
www.safespeed.org.uk

[Pies]

JD safespeed you've both friggin lost me

[jaydee]

safespeed said:

Whatever way you look at it, there's a substantial deviation from the long established trend which starts in 1993/1994. This is no two year glitch. This is a change established for a decade. Neither has it got ANYTHING to do with "regression to the mean" - what mean would that be then?

Having reviewed the graphs I'm afraid you've jiggled the stats to fit your argument. One can apply almost any curve to a very mountainous set of statistics, but the one you've chosen doesn't add up.

It's absolutely related to the regression to the mean. The line of best fit in fig. 3.1 is simply wrong and I'm sorry to say that, as elsewhere your arguments are very strong.

You're rejecting the existence of a mean diminution whilst using it as the basis of the argument. If you analyse the trend of the graph with all the data what becomes clear is that there are a series of 'spikes' throughout the history of the data.

This curious bit of jiggery pokery "In some cases we've averaged the official data over a rolling period of 3 or 5 years which has the effect of providing some "noise reduction" has served to smooth peaks and troughs" has reduced the visibility of historical 'glitches' but they are seen in the raw data.

The likelihood, based on the trend of the statistics, is that the mean 4% (ish-I haven't done the maths yet, but I can read the graphs ok) reduction in the fatacc rate will continue to apply in the longer term. There are instances which could be portrayed as more significant than the current blip '73-'79 being one example. A truer representation of fig. 3.1 through 3.8 is of all of them not as right skewed s-shaped curves, but as a straight line through -4%.

[jaydee]

Pies said:

JD safespeed you've both friggin lost me

Tedious argument to the non-obsessive Pies, I wouldn't worry yourself with it IIWY ! In a nutshell safespeed thinks there's a clear upturn in the trend of the incidence of RTAs and I remain to be convinced. The rest is simply proof that one can prove anything with statistics*

*96.2% of which are made up on the spot...

[Pies]

Ah he old "statistics statistics and dam lies" thingy

Slightly o/t but does either of you have the stats for
1. fatalities on our roads (any year pref most recent)
2. same year fatalities which involve a lorry in the accident



Cheers foe the explanation

[jaydee]

Pies:
1) yes, for 2001. 2002 stats. are under review (whatever that means) If you want them please email me (pdf)
2) No, AFAIK accidents involving lorries are not delineated. What you can find is the number of HGV drivers killed (120 in 2001)



Anyone who's interested (both of you ):
Further to earlier post: For reliable information on RTA deaths look for 1968 Vienna Convention Compliance

[Pies]

Bu66er,i read it somewhere that if you removed all olorries from our roads between 6am and 6pm deaths would drop by about 70-90%.As most accidents that involve a fatality involve a lorry

Can anybody prove or disprove it

[jaydee]

No. But I seriously doubt that 70-90% of fatal accidents between 6am and 6pm involve a heavy goods vehicle. IIRC (and I don't have the figures in front of me) the majority of fatal accidents are single vehicle.

[Pies]

Wonder if those figs related to motorways.Looks like i need to do some rsh

cheers

[safespeed]

hertsbiker said:

Safe speed, how about some rigorous enforcement of "Primary Pedestrian Safety" where kids in particular are taught the Green Cross code, and adults don't get pissed up & fall in front of cars. Why is is always the car drivers "fault" ? And tell me why in 1926 we had a tenth or twentyth of the number of cars, but more roads deaths than we do now? Could all this "Speed kills" issue be a load of b*ll*cks? howabout people taking responsibility for their actions as Pedestrians, not just motor users? perhaps if the namby-pamby way we bring kids up these days is the root cause of so many accidents. Certainly many kids my way are lippy little urchins who will deliberately step in your way to prove a point.

I don't have a clue why you directed this at me. I think individual responsibility is the fundamental of road safety - and I'd apply that to all road users including pedestrians.

Of course "speed kills" is a load of bollocks. I couldn't shout it any louder if I tried.

Best Regards,
Paul Smith
Safe Speed
www.safespeed.org.uk

[DennisTheMenace]

Paul , Just been having a nosey round your site , Great stuff keep it up

[cortinaman]

i think 20 limits are a great idea for outside schools from 7am-0930 then 1500-1630 but if road sense is being taught at schools it isnt being taught well enough.i was on the a127 at rayleigh wier and had the fortune of having 2 dikheads play chicken in front of me......they soon got out the way when i put the full beams on and dropped a gear.

i dont mind helping darwin's theory along and help our gene pool become less poluted with twa*s who cant understand that they CANT win a fight with the front of a piece of metal coming at them at around 70mph.

maybe getting rid of the bloody hedgehog road crossing crap would be a good start and replacing it with something that works.........hmmmmmmm........THE GREEN CROSS CODE?........

naah,thats just silly,i mean what could they learn from a great big bast in a superhero's outfit telling them to "look right,look left,look right again and if nothing is coming walk straight across" compared to a piece of 'roadkill' singing "king of the road"....

maybe its just me....i dont know.

>> Edited by cortinaman on Sunday 3rd August 01:33