[anshorei]

not agreeing with post you responded to, but you're misrepresenting them.

my understanding of the post is that he proposes speed limits should not be set so low as to increase the deviation between people following the speed limit and following their intuition i.e. they should approach average intuitive speed of the drivers using the road.

[brewdad]

We do seem to end up with a ratchet effect though. My town sets speed limits at the 85th percentile of speeds based on traffic surveys. Say the limit starts at 30. Most drivers assume a buffer before there will be enforcement, so they start driving 35. Next time the city studies that road, they raise the limit to 35 and drivers start going 40. Rinse. repeat.

Eventually, you end up like our main road through town where the limit is 45, the state limit for that type of surface street. Many drivers are happy to go 50 but the area has built up and also gets a lot of drivers unfamiliar with the area and those drivers go 30. It's a real mess and there are multiple crashes daily but I don't think the speed limit will ever be lowered. I think I've only seen the speed limit lowered on one road in the almost 20 years I've lived here. They only change in one direction.