Simply put, pedestrian safety is basic physics. The fundamental relationship here is really not that complicated, and there have been lots of charts showing the correlation between speed and fatality in crashes.
But these charts, via Streetsblog, are the best that I’ve seen yet, and they throw in the added variable of the age of the victim.
Here you go:
The fundamental relationship between speed and crash severity is one reason why I’ve been trying to get more attention to our state’s speed limit restrictions, where cities remain unable to set urban street speeds under 30 miles per hour (with a few exceptions for schools and bike routes, I believe).
A speed / visual perception chart.
The other important factor relating to speed is that it affects crash incidence, in addition to severity. The slower that drivers are going, the greater their ability to perceive a complex urban environment. And the greater amount of time ad river has to react to unexpected encounters, swerving or hitting the brakes. Speed is the crucial variable.
That’s why I believe the real goal of safety movements like Toward Zero Deaths should be to reduce the “design speed” of our urban roadways under 30 miles per hour.
(It’s a lot like the Strong Towns speed flowchart: Are people speeding? If yes, redesign the road with a lower design speed. Repeat until the problem is solved.)
Given the rash of tragic crashes, the basic problem remains the same.