Originally Posted by
PeterM
I deliberately modify my language to use collision or incident myself as a true accident is exceptionally rare. Normally someone has screwed up.
In ordinary English, accident simply means something unintended. Are you saying that most incidents are intentional? It is interesting to compare the analysis of aviation accidents with the above "Normally someone has screwed up". In aviation it has long been recognised that accidents do not have a single "cause", but are the result of the interaction of multiple factors, and investigation is aimed (in most countries) at preventing future accidents rather than blaming someone, a significant difference to the analysis of road accidents. The relative safety of the two modes of transport may suggest which is the more effective model.
I'm one of those people who like to see the devil in the detail for these things. As POD quite rightly pointed out, advances in trauma care have increased survival rates markedly. This kind of influence was demonstrated in wars as Korea and Vietnam saw the advent of medevac choppers and significant improvements in mortality rates.
The improved passive safety measures in vehicles and improved vehicle design has also lessened injury numbers and severity in crashes.
So, I'd like to see data that draws out the numbers of collisions per registered vehicle numbers; mortality and injury rates as a function of the number of collisions and then factor in on top of all that the distances that we drive.
I think some of this information is available from the bureau of statistics. The key figures are probably accidents per kilometre (no good handle on this seeing we do not have to log and report every kilometre driven, or minor accidents, - per registered vehicle is a very approximate substitute, but takes no notice of changes in vehicle use due, for example to people avoiding car use due to increased petrol prices, but is probably the best we have), and deaths per accident, probably fairly accurate.
The end result would be something along the lines that for every km that people drive the incidence of death or injury on the road is 'x' compared to 'y' from 'w' number of years ago.
In my view the major change is in road conditions and in driver attitudes, rather than improvements in vehicle safety - and this result will not distinguish the two effects.
That'd give us some rather interesting figures and a true measure of the relative risk. The number of factors that contribute to that relative risk are many and varied.