At 5mph your chance of surviving a collision is extremely high. Heck, you have a 93% chance of surviving a 20mph crash, depending on your age. Survival rates drop off quickly with speed however, with only 80% surviving at 30mph, and 45mph being a 50/50 chance for most of the population.
The effect is that slowing cars down from 35mph to 20mph in areas where pedestrians are close to cars could potentially double the chance of a pedestrian surviving a crash. And that’s not even accounting for how much less likely a collision is to happen at 20mph than 35mph.
Source: https://www.propublica.org/article/unsafe-at-many-speeds
Edit: of course, we can and should add more tech to make cars safer. That’s why backup cameras and seat belts are mandatory, and that’s a good thing. But as an argument for self driving cars, I think that they really come up short when there are tons of effective strategies available right now that we aren’t applying. And that’s my point.
The problem is twofold:
1. Cruise and co. may very well run out of money before they develop tech reliable enough to save people en masse. One proposal decades ago to solve the cars vs people problem was to physically grade separate them entirely, but as it turns out building multistory streets doesn't scale very well.
2. People and politicians, today, are using self driving cars as the magic bullet to avoid spending money on other solutions and changing bad habits. Why spend money on rail or buses if the second coming of Jesus for cars is around the corner? And to a degree, there is an opportunity cost to spending money on unproven X rather than proven Y.
what?
That being said, vehicle size is another uncomfortable subject when it comes to road deaths. If we really cared about not killing people on the road, we’d take a long, hard look at what cars we allow to operate on our roads.
Delivery trucks have the benefit of being obviously necessary; I am glad that trucks exist to deliver my food from the train depot (ideally) to my grocery store. But what’s the argument for Suburbans? SUVs not only drastically increase the risk for pedestrians, but they also make the roads more dangerous for other drivers to. For what? Status? A false perception of safety?
It is not just the energy involved from 5mph - not every accident is a cut and dry collision. A car doing 0.5mph still going to crush your skull when you go under the wheels.
People are killed frequently in London (and I am sure other places) when they are crushed by slow moving vehicles turning left or right and the driver just did not see the person there and they are either slowly run-over and pinned between the vehicle and something else and crushed.
Should we add tech to prevent these accidents? Of course. But let’s not kid ourselves about the actual numbers of where and why cars kill people.
As a means of comparison; back up cameras are mandatory to prevent children from being backed over at slow speed. This is an obvious improvement, but numerically quite small, with estimates being that it saves about 50-70 lives nationally per year. This is far less than the number of pedestrians and cyclists struck and killed in Los Angeles per year alone.
I agree that speed and general "cars forever!" approach is not great, but there is always room for improvement ... e.g. could tech have saved that 1 person who died in Oslo? Why just stop at "the Oslo model"? Why not do that and autonomous tech? It would be worth it if it saved just a handful of lives a year.