"Jules" wrote in message
...
This report in the BMJ was _years_ ago wasn't it?

It's all originally based upon the 'safety in numbers' principle doen by P
L Jacobson - Safety in Numbers: More walkers and bicyclists, safer walking
and cycling. Summary he

Objective: To examine the relationship between the numbers of people walking
or bicycling and the frequency of collisions between motorists and walkers
or bicyclists. The common wisdom holds that the number of collisions varies
directly with the amount of walking and bicycling. However, three published
analyses of collision rates at specific intersections found a non-linear
relationship, such that collisions rates declined with increases in the
numbers of people walking or bicycling.
Data: This paper uses five additional data sets (three population level and
two time series) to compare the amount of walking or bicycling and the
injuries incurring in collisions with motor vehicles.

Results: The likelihood that a given person walking or bicycling will be
struck by a motorist varies inversely with the amount of walking or
bicycling. This pattern is consistent across communities of varying size,
from specific intersections to cities and countries, and across time
periods.

Discussion: This result is unexpected. Since it is unlikely that the people
walking and bicycling become more cautious if their numbers are larger, it
indicates that the behavior of motorists controls the likelihood of
collisions with people walking and bicycling. It appears that motorists
adjust their behavior in the presence of people walking and bicycling. There
is an urgent need for further exploration of the human factors controlling
motorist behavior in the presence of people walking and bicycling.

Conclusion: A motorist is less likely to collide with a person walking and
bicycling if more people walk or bicycle. Policies that increase the numbers
of people walking and bicycling appear to be an effective route to improving
the safety of people walking and bicycling.

This work was then looked at by D Robinson, you can view it he

http://www.bfa.asn.au/bfanew/pdf/pub...in_numbers.pdf

It shows that the safety in Numbers principle 'works' for Australia, and
draws the conclusion that discouraging cycling by whatever means (even if
'safety focussed') is more detrimental to public health than encouraging it.

The helmet stuff comes in to the mix because there was an approx 30% instant
drop in the numbers of cyclists at the time of mandatory helmet wearing.
And now she's published another article, which I can't access until I get to
work on Monday..... :-)

And.... look out soon for some South Australian research on the Safety in
Numbers principle..... to be published.