Disagree - if traffic flowed more evenly, same speed for everyone, less lane changes, didn’t require the “safe distance padding” re-establishment at every light, the congestion would lesson. Probably not eliminated though.
Yes, if the amount of traffic stayed the same, having all self-driving cars would be a big improvement. But what I'm saying is that a lower cost of commuting (in terms of attention, effort, and danger) would induce demand. People would hate commuting a lot less, and therefore more people would do it. To offset that you'd need to either increase the speed dramatically or do something else so that more people can fit on the roads. Maybe smaller cars. Maybe pack self-driving cars automatically into trains. Maybe build a lot more roads.
But whatever it is, you need something major to counter the increase in commuters or else the road system will get swamped.
