My problem was the conclusion: "As a nation, drivers in the United States travel slightly too fast and could improve overall life expectancy by decreasing their average speed slightly."
As a nation, drivers in the United States travel at pretty much the average speed. (See: http://en.wikipedia.org/wiki/Speed_limits_by_country) The national comparison seems like a rhetorical device, suggesting American's do something inferior to other countries, therefore we should change to keep up. Instead, you should only conclude that a decrease in speed could increase life expectancy.
Perhaps you're right regarding what the comparison is inviting. It might not be suggesting cross-country comparisons, but it's still making a normative statement concerning the ideal. My contention is that it should not do that; it should only focus on the decreased probability of death by reducing speed. Weighting the trade-offs is too objective.
A Canadian paper on US data, not enough people actually live in Canada for cars to approach each other on average. (I'm Canadian, but also making fun of the abuse of averages to describe this data).
Money quote: "While traffic fatalities from 1979 to 2000 declined by 50% in Canada, 46% in Britain, and 48% in Australia, the decline in the United States was only 18%."
What are the absolute rates? Here was a quote I enjoyed from your link that borders on tautology:
My more than 30 years of traffic safety research leaves little doubt that the 2 factors that overwhelmingly determine an individual’s risk in traffic are (1) the individual’s behavior and (2) the behavior of other road users.
Why does the author need over 30 years of research to come to this conclusion?
My anecdotal experience is that almost everyone is oblivious to the second factor. "Yeah I drive over the speed limit/tailgate/drive a motorcycle, but I'm a much better driver than the average idiot so it's not dangerous for me."
As a nation, drivers in the United States travel at pretty much the average speed. (See: http://en.wikipedia.org/wiki/Speed_limits_by_country) The national comparison seems like a rhetorical device, suggesting American's do something inferior to other countries, therefore we should change to keep up. Instead, you should only conclude that a decrease in speed could increase life expectancy.