A fleet of autonomous vehicles transporting people from disparate point to disparate point still requires a lot of roadway space per human being transported, which is the root cause of road congestion. That is as true in 2016 as it was in 1916, and will remain true in 2116.<p>Fixed-route rail transit requires compatible land use to be successful, but most of our most economically successful areas are already very dense— and the only reason than Silicon Valley isn&#x27;t is that such density is illegal, with the absurd result of $2M ranch houses. A bilevel rail car can comfortably transport 160 people in the footprint of four Honda Civics cruising as an autonomous car-train.