In a dense urban area, the speed limit is generally not dictated by road design but by the simple physics interaction between a person made of meat and bones, and a multi-ton metal vehicle.

Follow distances in urban areas with low speeds are already really small. I don't think AVs would make them meaningfully tighter.

> Part of reacting and mitigating acute issues is being able to reroute traffic early enough, or slow cars down early enough, to minimize disruption (instead of a traffic slinky blocking everyone up).

This was supposed to be what Waze and Google Maps were set to achieve, and they did not, but they did piss off a lot of people when cut-through drivers started jamming up their formerly quiet residential neighborhoods.