Effects of Speed on Pedestrian Fatality Rates - 40 MPH is 16X more dangerous than 20 MPH | HumanTransport.org

Headlines are quick hits from media outlets from Missouri and around the world. Follow the headline link for the full story. The source of this headline says:

Newton's laws dictate that a doubling in vehicle speed results in a stopping distance four times as long and four times as much kinetic energy absorbed during an impact. Driver response times further increase stopping distances. As a result, a small increase in roadway traffic speeds results in a disproportionately large increase in pedestrian fatalities. This relatonship is illustrated in the references listed below. . . .

"For both stopping distances and the severity of crashes, speed matters. Travelling at 40 mph, the average driver who sights a pedestrian in the road 100 feet ahead will still be travelling 38 mph on impact: driving at 25 mph, the driver will have stopped before the pedestrian is struck." . . .

The following table shows how, when a pedestrian is struck, the likelihood of death increases faster than the percentage increase in vehicle speed, in a nonlinear fashion:

Relationship of Vehicle Speed to Odds of Pedestrian Death in Collision

Vehicle Speed - Odds of Pedestrian Death, Source 1 - Odds of Pedestrian Death, Source 2

20 mph - 5% - 5%
30 mph - 45% - 37%
40 mph - 85% - 83%

MoBikeFed comment: Reducing traffic speed has proven to be one of the most effective means of reducing traffic injuries and fatalities. The reduction is true for pedestrians, but also for passengers in motor vehicles and for cyclists.

Reducing traffic speed in the places where people live is one of the most important and effective strategies used in Vision Zero, which has proven to be the most effective program for eliminating traffic fatalities and reducing injuries.