Geoff, I take it you didn't take time to read about Barcelona? Is it that you just want to predict doom rather than look for solutions?
---
Let me give you one idea, sort of a Barcelona spinoff, that we might be able to implement once we get self-driving cars.
Take four adjacent streets running the same direction (N/S or E/W) across town. Assume all have at least four lanes, including the parking lanes.
Turn two into four lane one-way, no parking or stopping thoroughfares. Center two lanes for cars that will travel several blocks before turning off. Outer lanes for cars turning on and turning off as well as going only a short distance.
Stop for passenger entry/exit and deliveries on cross streets. Keep the cross streets free of parking so that a robotaxi could turn onto a cross street, discharge/pickup passengers, make a u-turn and resume traveling in the same direction.
Turn the other two streets into pedestrian and bike friendly roads. One center lane for slow speed (10 MPH max) cars going only a limited distance, normally only one block. Provide space for vehicles picking up and dropping off passengers and for deliveries.
EVs will take care of the noise and pollution. Self-driving cars can drop off their passengers and take themselves to a parking area (or in the case of robotaxis, off to haul someone else). Self-driving cars (programmed correctly) will not hit people.