In some places, that's how speed limits are fixed.
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...
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.
I don’t feel like setting the speed limits at whatever people “think is safe” is a good idea, and the deaths confirm drivers are really, really bad at determining what is safe.
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.
Sure, driving to the supermarket doesn't change much at 20mph vs 35mph. However, you may want to start speeding more situational as a lot of the lights feel very interconnected so rather than constantly hitting the same red you can speed before it to get a yellow.
Speeding largely just increases consequence of an accident but the thing that's causing them in the first place is looking at your phone. Adjusting how fast people can go won't fix then unless you dial it all the way down to 10mph.
Assuming the speed limit is 65 and you're driving at 75 that's quite normal but on a 1 hour journey you've saved ~9 minutes. Maybe worthwhile if you're going to the hospital but mostly not worth the stress and increased risk to others.
Also speeding is a major cause of accidents, even before cellphones were pervasive. https://www.iihs.org/research-areas/fatality-statistics/deta.... Also found another report dating back to the 90s that says the same thing but it's a pdf.
Most highways around me at 55 so it's 16 minutes. It improves much more when compared to 45 which is common to see people at because they cannot use their hands and feet at the same time (curvey roads).
> In 2024, speeding was a factor in 29% of motor vehicle crash deaths.
Well yeah of course speed is involved in a crash. You can't have a crash with two parked vehicles. Faster speeds make an accident worse but the accident occurs because somebody didn't break in time or look where they were going (common with pedestrian strikes as right turning vehicles don't look right for peds; just left for cars).
Them finding only 8% of accidents involved a distracted driver is highly suspicious. Anecdotally the amount of times I see people leaving lane unintentionally while also either staring at their crotch or holding a phone to their mouth is way beyond 8%.
But the US democracy/political process plus the different states can lead to "vote for this speed limit" as well as widely varying traffic laws in different states.
Personally I think if you want super low speed limits, instead of just enacting them and expecting compliance, maybe use traffic calming devices and other reality-based methods. The united states is not one culture.
I found japan interesting. japan is a high trust, high compliance culture. A (US) friend lives there most of the time with his japanese wife and he told me how things work. The driving tests are very comprehensive and expensive. Also, if you're from the united states, they fail your test the first time you take it. They just assume someone driving on the right should not pass. They don't seem to do that to folks from australia/england.
But the method of increasing speed limits because everybody is breaking the current limit is clearly just bad engineering practice.
You start by over-designing and over-building the road, then you add spit limits to slow it down, and then you realize that everybody still speeds and you up the speed limit.
That just evidence of a broken culture around safety and road design. And people are paying for it with their lives.