[ExI] US traffic deaths dropped to new low

[BillK]

On Fri, Apr 15, 2011 at 3:28 PM, spike  wrote:
> Thanks BillK, but again it isn't as clear as that.  Sure we can compare
> numbers and we have lots of good mathematical tools for doing that.  But the
> question remains, which are counted and why?  We saw in the pedestrian
> fatalities statistics a factor of 8 disagreement based on how they are
> counted.  Which is right?  When we see numbers like those above, are we free
> to assume a factor of 8 uncertainty?  Plenty of cases are unambiguous, but
> many are debatable how they should be counted.
>


There is no discrepancy between the two sites that you quoted.

They are both interpreting the same study.

One is quoting pedestrian fatalities per 100,000 residents and the
other (quoting from the actual study) is quoting the Pedestrian Danger
Index.  The Index is a calculated figure and has no direct connection
with the number of fatalities.
Quote:
Researchers at the Surface Transportation Policy Partnership in the
1990s developed the Pedestrian Danger Index (PDI) in order to
establish a level playing field for comparing metropolitan areas based
on the danger to pedestrians. The PDI corrects for the fact that the
cities where more people walk on a daily basis are likely to have a
greater number of pedestrian fatalities, by computing the rate of
pedestrian deaths relative to the amount of walking residents do on
average.
-------------------


> This uncertainty may get worse as the population ages and cars actually get
> safer and better.  Driver has heart attack, drives into a tree.  Perhaps the
> driver was dead on impact, but it isn't worth doing an autopsy to find out.
> Counted as a traffic fatality?  Would not that driver have had a heart
> attack anyway?  Driver has heart attack, crosses centerline, slays an
> oncoming prole.  One traffic fatality or two?
>
>


Heart attacks while driving are a tiny factor in the total carnage
figures. But, even so they should still be included as a pointer to
the need to make car crashes more survivable. If the driver has a
heart attack it would be nice if crumple zones, airbags, safety belts,
and other measures mean that all the passengers survive.


BillK