well, if that was the result they got, i'd definitely like to see the data. but i'll drop it, before it gets personal. Russell McMahon wrote: > > Summary: > > I demonstrate (I believe), using 'real; data, that Phil's statements that > > "the statement you made as fact is absurd" and > "it's lying, it's fraudulent, and it's disrespectful" and > " ... when you say "statistically" you are claiming there is data, in this > case there obviously isn't." and > " you made an absurd statement and claimed it was at least statistically > valid without even having statistics." > > are, to use his terminology, obviously absurd. > I'm not sure if they are disrespectful etc :-) > > Two examples of chapter and verse are provided. > > (European Traffic Safety Council / University of Zurich / Swiss Federal > Institute of Technology) > Google sufficeth for more such. > > "New directions in speed management: a review of policy" > UK Government Road Safety and Environment Directorate, Review of Speed > Policy. > > It MAY, perhaps, be that Phil will realise that he was attacking something > that I was not saying. > Maybe not. > > ______________________________________________ > > So: > > Phil got somewhat upset that I said: > > > > > Statistically, taken over a year's results (or even a week's) you'll > find > > > > that pedestrian fatalities increase approximately with the square of > > > vehicle > > > > speed (see my "longish" post on this recently). > > > ----------- > > Hmm - this seems to be me that you are, er, waxing philosophical, about. > The man you are replying to about it aint the guy who wrote it. > > When joining a list its probably wise to soak up a bit of the ambience and > found out who says what about what and how reliable people are and how prone > to factuality and .... before coming out all guns blazing (or even with half > your guns blazing). AGB may work, or you may end up with egg on face (if I > may mix metaphors). > > I could point by point address your concerns, but I'll (largely) stick to > one which was the main basis of my other points. > > Do note the "see my ...". > FWIW I would have thought that, to an engineer, the claim would have a > somewhat intuitive feel on reflection. > Indicivual accidents vary widely. There's high and low bumpers, tall and > short people, over the bonnet, glancing blows and full frontal, (I and my > motorcycles have been subject to both of these), through the windscreen etc. > Some accidents are somewhat energy independent - if you get run over the > vehicle speed is liabl;e to be less important than the crushing effect. But, > for most accidents, the energy that is impatrted to your body is liable to > be a significant factor in the damage done - both when the vehicle adds > energy and when the road etc subsequently removes it. FWIW In my two car > versus bike accidents I got more damage at the time that I had energy added. > As energy added to you is related to velocity squared you would expect a > degree of correlation. > > But you say, and I don't know why - > > "yes, to state a mathematical equation, without support, is basically > manufacturing data, or put another way, lying." > > & (ignoring various castings of doubt upon my veracity & respectfulness ... > :-) ) > > > the statement you made as fact is absurd, > > & (re the affect thereof) > > > it's lying, it's fraudulent, and it's disrespectful, > > & > > > ... when you say "statistically" you are claiming there is data, > > in this case there obviously isn't. > > & > > > you made an absurd statement and claimed it was at least statistically > valid without even having statistics. > > & > > > if i say something absurd and claim it's fact, i damn well expect to be > called on it, > > So, consider yourself called :-) > I suggest that before you getso involved ina response that you: > > - make sure of the context and claim. > - do a sanity check on the physics > - Use Google > - Use Google again. > - Remember that Google is your friend. > > You will, with digging, be able to find enough on this to satisfy you, but > here's a start: > > European Traffic Safety Council 1995, University of Zurich and Swiss federal > Institute of Technology 1986. > Cited by Geetam Tiwari, Traffic Flow and Safety: Need for new models for > Heterogenous Traffic. > > > > Figure 2 on page 73 is an approximately square law graph and the supporting > text notes - > > "As illustrated in figure 2, small reductions in travelling speed result in > large reductions in injuries and fatalities in both urban and rural areas. > This is because the stopping distance of a vehicle under braking is related > to the square of the original velocity and > the damage to human beings is related to the square of the impact velocity." > > He provides typical fatality versus speed figures. > I present these below along with those predicted by my rule of thumb > empirical formula. > (This rule of thumb empirical formula, was referred to in my subsequent post > which you objected to.) > > Speed My % fatal His % fatal > > 30 18 5-8 > 40 32 25 > 60 72 > 85 > > It will be noted that his figures rise from below mine at low speeds to > above mine at high speeds. My curve is square law - his is somewhat steeper > than square law. > > So, it seems, that in this case at least, the tabulated matches the sensibly > expected. > > ________________________ > > Lets have one more bite at it - > > "New directions in speed management: a review of policy" > UK Government Road Safety and Environment Directorate, Review of Speed > Policy. > ? ~= year 2000 > > Whole report as PDF > > http://www.dft.gov.uk/stellent/groups/dft_rdsafety/documents/pdf/dft_rdsafety_pdf_504682.pdf > > OR > Report top level > > ety_504682.hcsp> > > Section of especial relevance. > > ety_504682-03.hcsp#P87_10088> > > which contains ... > > _______________ > > Speed and injury severity > 41.The likelihood of being seriously injured in a collision rises > significantly with small changes in impact speed. The impact speeds at which > this increase is most pronounced are lower than most would think. The > probability of serious injury to a belted car occupant in a front seat at an > impact speed of 30mph is three times greater than at 20mph. At 40mph it is > over five times greater (Hobbs and Mills 1984), see annex. > > 42.For pedestrians and cyclists the reality is even more stark. At-the-scene > investigations of collisions involving pedestrians and cars or car-derived > vans found that 85% of fatalities occurred at impact speeds below 40 mph > (Ashton and Mackay 1979). This compared with 45% which occurred at less than > 30 mph and 5% at speeds below 20 mph. > > 43.About 40% of pedestrians who are struck at speeds below 20 mph sustain > non-minor injuries. This rises to 90% at speeds up to 30 mph, see annex. The > change from mainly survivable injuries to mainly fatal injuries takes place > at speeds of between about 30 and 40 mph (Ashton 1981). Elderly pedestrians > are more likely to sustain non-minor injuries than younger people in the > same impact conditions. > > ________________ > > Fatality comparison my formula versus UK reported figures. > > MPH Me% Them% > > 20 22% 5% > 30 50% 45% > 40 88% 85% > > Again, their rise is slightly MORE than square law. > > The attached GIF, which is based on the data from the UK report (not of my > drawing) is a bit tiny as I wanted to keep its file size down, but shows > clearly enough the non-linear rate of fatality increase with impact speed. > (fatalities are the right hand curve, middle curve is non-minor injuries, lh > curve is sum of other two). > > Enough for now I think. > > Russell mcMahon > > -- > http://www.piclist.com hint: The PICList is archived three different > ways. See http://www.piclist.com/#archives for details. > > ------------------------------------------------------------------------ > Name: killspeed2.gif > killspeed2.gif Type: GIF Image (image/gif) > Encoding: base64 -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.