A few choice sentences from John Staddon's article on road safety:
Paradoxically, almost every new sign put up in the U.S. probably makes drivers a little safer on the stretch of road it guards. But collectively, the forests of signs along American roadways, and the multitude of rules to look out for, are quite deadly.
This article available online at:
http://www.theatlantic.com/daily-dish/archive/2008/06/the-deadliness-of-safety/215288/
