What I remember reading about the impact of speed limits is that reducing them only affects the slowest quartile or so of drivers while changes to road design such as reducing road width and visibility slow down almost all drivers. Reducing the speed of some drivers and not others increases aggressive driving and probably isn't good for safety.

I don't take the position that reducing speed is a good answer for every high-risk road situation, but for those where it is, changing the speed limit alone is likely a poor solution.

> reducing them only affects the slowest quartile or so of drivers

And having to navigate traffic that is not of a homogeneous speed creates cognitive load for all drivers. So then they don't notice things like cyclists and pedestrians.

That makes no sense. Mixed use and mixed speed creates an environment where drivers have to notice diversity of traffic, including cyclists and pedestrians.

> I don't take the position that reducing speed is a good answer for every high-risk road situation

Why not? There's clear evidence showing that crashes at higher speeds are much more deadly. IMO any street that allows pedestrians and bicycles should be designed for 20mph car traffic. If you want to drive faster than that, do it on a limited-access highway.

There are multiple solutions to your 20mph car traffic restriction, one of which is “disallow bicycles and pedestrians on this stretch of pavement”.

Limiting access to the road, e.g. using pedestrian overpasses, fencing, segregated sidewalks and bike lanes, etc... is among the options I had in mind. I don't think one solution fits every problematic road.

Roads aren't badly designed because no one has "reported" them. Improving roads for pedestrians needs to be a priority for politicians, instead of convenient commuting by cars. And for that to happen, voters need to see the world like it is: drivers run over pedestrians.