Don’t Design Streets For Death

by Chuck Banas, Urbanophile

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If pedestrians are being endangered, the design speed of the road is usually the culprit. Many if not most roads in this country are intentionally designed for much higher speeds than the posted limit. A 30 mph speed-limit sign on a road designed for 50 or 60 mph is a futile—and sometimes fatal—exercise in wishful thinking.

Pedestrian Injury Frequency and Severity Based on Vehicle Speed (Source: National Highway Traffic Safety Administration, image from the Bicycle Alliance of Washington)

Here are the sobering facts: at 30 mph, vehicle-pedestrian accidents are fatal in about 5% of cases; at 40 mph, fatalities are 90%. This is not to mention injuries, which can be devastating in their own right: incapacitating injuries are significantly less likely and less severe at slower speeds.

Done properly, traffic throughput is still maintained, with less stop-and-go frustration for drivers, and much greater safety and civility for all users of the roadway, including pedestrians and bicyclists. For the vast majority of surface roads, there is simply no reason to design for a speed limit over 30 mph. Doing so seems careless and downright irresponsible, but this is the unfortunate norm for most highway departments.