If speed limits are impractical they have to be fixed.
Were a car to refuse to exceed the speed limit, it would be dangerously slow almost everywhere in the united states, arguably reducing safety substantially.
Because the other cars are speeding too.
> Notably, any reduction in danger that flows from breaking the speed limit is only for the car and other cars breaking the speed limit, in no case it is for pedestrians, cyclists or other non-vehicle participants in traffic.
Correct.
Speed limits in a vacuum are largely about revenue generation. There's ample evidence backing numerous practices that actually slow traffic, things like using traffic circles instead of intersections, reducing the width of lanes to promote slower travel, speed humps, separating traffic that's going a distance (roads) at speed, from slower traffic preparing to enter residences/businesses (streets). Lots of stuff.
Limits though? I mean they probably don't do nothing but they aren't nearly as effective unless you pair them with a regular police presence. And even then, mixed effects. I'm pretty sure the entirety of the Chicago Loop is capped at 55 mph, but if you actually do 55 on that thing, you're gonna die.
As to the topic of the thread: truthfully, IMO, parents should be barred from ferrying their kids to school. Not only is it just a "commute but worse" in terms of ecological impact (the car goes, drops the person, returns home, then returns later, picks up, and returns home. Literally 2x the normal traffic impact) but also it's ridiculously inefficient for similar reasons. School traffic everywhere I have ever lived has been a goddamned nightmare. I would rather be stuck on the highway jam ten times than be trying to navigate around a school full of stressed, harried parents driving big stupid SUVs, who themselves are surrounded by children, who themselves are entering and exiting vehicles at random.
School busses are the safest vehicles on American roads, and starting kids on them early gets them comfortable with the idea of mass transit. Dictionary definition of a win/win.
I actually look forward to self driving taxis/etc doing the speed limit for this reason. It's going to be difficult to speed if there are always vehicles doing the speed limits in various lanes (where passing lanes don't exist, at least)
One source of pressure to keep speeds high is that if municipalities can classify a street as a collector or arterial, they can get federal aid for projects related to the road. As such cities will often want to bring a local road up to collector or arterial status so that they can get higher federal funding for it. (Collectors and arterials usually are larger streets with higher speed limits, though the biggest gray zone is between collectors and local roads and often the biggest difference is indeed the speed limit.) Urban planning discourse about "stroads" in the US is largely a story of local roads that have eventually been classified as collectors or arterials so retain the residential or commercial density of a slower road but are expected to have the speeds and vehicle volumes of faster roads.
(FWIW I first saw this on city-data in the early 2000s and vaguely heard my parents' generation say similar things to this comment, but when I actually started listening and attending local meetings I realize that it's mostly an urban legend that gets repeated to each other.)
https://en.wikipedia.org/wiki/National_Maximum_Speed_Law
"...the National Maximum Speed Limit (NMSL) was enacted in the 1974 Emergency Highway Energy Conservation Act that withheld Federal Highway funds from States that refused to comply with provisions of the law, including a maximum speed limit of 55 miles per hour (89 km/h) for passenger vehicles, an increase Nixon approved in signing the final legislation."
In Texas, for example, they do a traffic study and set the limit to the 85th percentile speed.
https://www.txdot.gov/safety/driving-laws/speed-limits/speed...
So, if a road feels "safe" at 60mph to people, and you put the speed limit as 20 the average traffic might be 40mph. If you put the speed limit as 40mph, it might go up to 55mph. If you put the speed limit as 60mph, it might go up to 65 mph.
But that natural tapering is what lets you find a stable value for a specific percentile threshold.
Our highways also train you that speed limit are complete bullshit. On an 8 lane, divided highway, with nothing but empty field or protective barriers on either side, 60 mph is comically low. That's how you end up with absurdities like it often being unavoidably illegal to drive on 680 in the Bay Area: either you're speeding, or you're obstructing traffic, both of which carry a fine.
IMO, the correct answer is to raise the speed limit of surface streets that already double as psuedo-highways (looking at you, San Jose), strictly enforce speed limits on surface streets, and then completely eliminate speed limits on the freeways.
Stop using dangerous hw features.
That's the kind of person I expect who speeds in a school zone.
(Also, the second case is something a car manufacturer should probably be resolving more by not hogging the overtaking lane than defaulting to going 20mph over the limit for extended periods because everybody else does)
What consequences does Elon Musk face when his autonomous cars do the same?
I hope the Nordics prevail and the Europeans don’t follow his bullshit.