That will work up to a point, but I would bet there are many situations where the amount of cars that want to be on the same piece of road at the same time overwhelms those kinds of measures. And with the same result since congestion force everyone’s speed to be lower anyway.

I can think of quite a few chokepoints in the US (Manhattan/SF-San Jose/LA/Seattle/Austin) where no matter what you do, the crush of cars will be too much for the roads that exist.

In these cases though, I think public transit is the only real solution, but that is a different topic.