Tucson built a loop sometime after I had to leave 23 years ago.
https://www.arizonabikerides.com/rides/586/the-loop-bike-ride-tucson/
no cars, just bikes, joggers and people walking.
When I'm done with this vintage build I may start looking for a modern bike. Titanium or graphite.
I've been rolling around some ideas of building a home grown carbon bike. It would be made out of pieces like a steel brazed bike with lugs, but glued together like a composite airplane.