Here is the hard data on a person’s probability of survival when hit by a car traveling at a range of speeds. You should go to the link and look at the graphs, but here are a few highlights I picked out:

• For the average person hit by the average vehicle, you need to get speed down to the 30-35 mph range to have a 75% survival probability, and the 20-25 mph range if you want a 90% survival probability. 15 mph would get you up to about 95%.
• All people are not average. A 70-year-old struck at 30 mph has something like a 60% chance of living, while a 30-year-old has more like a 85% chance (I’m eyeballing a tiny graph, these numbers are not exact.)
• All vehicles are not equal. Getting struck by a pickup truck or SUV is more likely to be deadly than a car. Again just eyeballing, if you’re hit by a light truck vs. a car at 30 mph, the average person’s odds of survival would drop from something like 80% to 75%.
• Those numbers are for death. Obviously, the risk of severe injury short of death is higher. Again using the 30 mph example, the risk of severe injury for the average person hit by the average vehicle looks to be around 50%.

I think our first instinct is to look for someone to blame – and it’s obviously true that better driver behavior, pedestrian behavior, or both could prevent accidents. But police enforcement is obviously part of the answer. It upsets me when I hear the Philadelphia Police openly say they don’t enforce traffic laws because they have “real crimes” to attend to. Sure, their job is to keep the population safe from violence on our city’s streets – well, this is violence on our city’s streets! And it disproportionately puts children and the elderly at risk compared to other forms of crime.

Finally, better design of streets, intersections, and signals is a big part of the answer. Nearly perfect designs exist in places like Denmark and the Netherlands, but well-trained and well-intentioned U.S. engineers are either ignorant of them or cynically assume they can’t or won’t work here, or that they are not affordable.

I assume these same police and engineers would not go out on the streets and shoot old people and children in the head, because that would be unethical, so why is knowingly allowing the preventable deaths of old people and children through ignorance and negligence any different? And why does the public largely accept this and assume it can’t change?