I agree that an independent study would be very useful to get a better idea of what's actually happening.
That said, human drivers in the US are bad. We have the highest traffic crash rate among all developed countries by far. Pedestrian and cyclist crash rates have been increasing in the US, one of the only developed countries in the world that this is happening in. Much of the US remains opposed to automated traffic enforcement or speed governors of any kind. Privacy advocates use privacy as an excuse but given how much Americans care about their privacy in other aspects of their life, I'm doubtful. And anecdotally it's common for friends to talk about driving 10-15 mph over the speed limit, and we know speed is the leading predictor for severity of a crash. Most US drivers, especially of higher income classes, are probably well aware that they speed and break plenty of other traffic laws on a regular basis and don't want to reckon with that fact.
> And anecdotally it's common for friends to talk about driving 10-15 mph over the speed limit, and we know speed is the leading predictor for severity of a crash. Most US drivers, especially of higher income classes, are probably well aware that they speed and break plenty of other traffic laws on a regular basis and don't want to reckon with that fact.
Because 99 44/100 percent of the time, this is not a factor. The true threat is not someone going 10 over on the highway, it's the loons you see zooming ahead of everyone else going 20+ over, weaving like they're in a video game. Equally unsafe are the self-appointed speed police camping in the left lane doing 2 under (looking at you, Greater Seattle). This forces people to pass on the right to keep up the flow of traffic, which is much less predictable.
The correct answer is to keep right except to pass, keep your speed within reason (<10 over max in good weather), keep a decent following distance, and let the cops take care of anyone driving recklessly. If speed was so dangerous by itself, Germany would not have Autobahns.
As a German, I'd like to point out that about half of the German Autobahn network do have speed limits in place, or had in 2019 (this oscillates a lot between about 30-60%, I think).
According to a government study into Autobahn fatalities that occurred in 2018, "non-adapted speed" (defined as the appropriate speed for the traffic conditions and allowing full control of the vehicle) was the cause of death in 45% of cases overall. For stretches without a tempo limit it was 46%, for stretches with one it was 50% -- this may be a good statistical for the tempo limits, as presumably there would have been more deaths on those stretches without the limits having been set.
Overall, 70% of Autobahn deaths occur on the segments without a tempo limit for a variety of reasons.
Speed limits on the Autobahn are a frequently-discussed and controversial topic in Germany, but for what it's worth, they're quite actively managed for safety reasons.
I'm not denying any of this. I'm just observing that there's a faction in the US which seems to say "speed is a leading factor in car deaths" (which it is) and then insists on everyone never going 1mph over our often-arbitrary-and-politically-set speed limits. When what you're describing as "non-adapted speed" is exactly the actual problem . . . driving beyond one's capabilities or the capabilities of one's vehicle.
Our freeways stateside were largely built in the late 20th century to a uniform 70mph (~110km/h) speed limit engineering-wise. But after the 1970s oil crisis, speed limits became a political football that often have as much to do with driving traffic ticket revenue for local governments as actually promoting driving at a safe speed.
So the problem is that a portion of Americans commenting on our speed limits don't understand there's a difference between "what the government puts up on the sign" and "what is actually a safe speed to drive without endangering other people" as if what's on the sign is some sacred totem that shall not be questioned because We Must All Follow The Rules Like Good Little Boys and Girls.
What the government puts on the sign has significance you know. Maybe the highway was made in the 1950s vs 1970s and interchanges are too tight. Maybe its a surface road with smaller measured sightlines than you might realize. All the yellow lights are going to timed with respect to the posted speed limit and braking distance. All green waves timed with the anticipation you go the posted speed limit.
So let everyone decide to decide for themselves what a safe speed should be on any given stretch of road and see what happens? In other words, let evolution find the 'safe' speed.
Yes, though you are phrasing it negatively. Something like 90% of drivers base their speed on conditions, not on the speed limit signs. No amount of arguing that it should be exactly the opposite will actually make that happen, so we have reality to work with. We can whine on an Internet forum that terrible people are not abiding by the posted speed, or we can engineer the roads to meet our goals.
That said, human drivers in the US are bad. We have the highest traffic crash rate among all developed countries by far. Pedestrian and cyclist crash rates have been increasing in the US, one of the only developed countries in the world that this is happening in. Much of the US remains opposed to automated traffic enforcement or speed governors of any kind. Privacy advocates use privacy as an excuse but given how much Americans care about their privacy in other aspects of their life, I'm doubtful. And anecdotally it's common for friends to talk about driving 10-15 mph over the speed limit, and we know speed is the leading predictor for severity of a crash. Most US drivers, especially of higher income classes, are probably well aware that they speed and break plenty of other traffic laws on a regular basis and don't want to reckon with that fact.