"Speeding traffic sets in motion a vicious cycle in which people who
might prefer to walk or bike end up driving out of fear for their
safety. Numerous studies have shown that the speed of traffic, much
more than the volume, is what poses a threat to pedestrians. One study
conducted by the British government found that pedestrians were killed
85 percent of the time when they were hit by cars traveling 40 miles
an hour compared to only five percent of the time when vehicles were
traveling at 20 miles per hour."
http://www.emagazine.com/view/?2307&printview
