“How many cars go down your street each day? How fast were they going? What about folks out on a walk or people riding bikes? It’s not an easy question to answer, as most of us have better things to do than watch the street all day and keep a tally. But at the same time, this is critically important data from an urban planning perspective.”
Certainly could be an interesting project to build (I suppose any local authority would pay a fortune for someone to provide this for them normally).
It can run off a Raspberry Pi, and it does process the data locally, which is good for privacy.
See https://hackaday.com/2025/03/11/homebrew-traffic-monitor-keeps-eyes-on-the-streets