Research: Risk of death for pedestrians, cyclists increases dramatically as motor vehicle speed increases 20-40mph

During the peak of the COVID shutdown, many drivers became used to driving very fast on mostly-empty roads.  Now that traffic patterns have returned closer to normal, a certain group of drivers seem to be continuing their fast-driving habits.

Unfortunately, fast driving has disastrous consequences when the fast-moving car meets a pedestrian, a bicyclist, or another vehicle.

Here is a research summary from ProPublica that shows just exactly how much difference it makes when a motor vehicle is traveling just 10 or 20mph faster:

Once cars reach a certain speed (just above 20 mph), they rapidly become more deadly. According to Tefft's data, a person is about 70 percent more likely to be killed if they’re struck by a vehicle traveling at 30 mph versus 25 mph.

 

If you live in New York City, those two numbers may sound familiar. That’s because in the fall of 2014, Mayor Bill de Blasio signed a law lowering the default city speed limit from 30 mph to 25 mph. Speed limits are just one part of Vision Zero, a citywide initiative to create safer streets for all New Yorkers, who are seriously injured or killed by cars at a rate of one person every two hours. And there is some evidence that the initiative is working — 2015 saw the fewest traffic deaths recorded in NYC for any year since 1910 (a total of 231 deaths, 134 of which were pedestrians).

While some people see the speed limit adjustments as a traffic-slowing nuisance, for those who get hit, it could actually make a huge difference in how likely they are to survive.

“Indeed, the risk [of death] increases dramatically between 20–40 mph" . . .

For this reason, a major emphasis on tactics that reduce motor vehicle speed, in any situation where motor vehicles are more likely to come in contact with  vulnerable road users, is one of the priorities of Vision Zero.

More information and research on this issue from Streetsblog USA.