There is a bit of discussion going on in the Amazon thread about autonomous cars, but rather than adding my post there (since it was off topic), I figured I'd just start the discussion here.
I think people are focusing too much on the way cars look and function today, and don't consider that our vehicles can and will come in very different shapes and sizes. Somebody could come up with a one seater car that takes up only 1/4th of the space on the road (or even less without needing room for a trunk or engine). If all cars are autonomous, we don't need cars to 'safely' drive two cars length behind each other, meaning we are going to use our road space more efficiently. Lanes could become narrower, because computers are far more precise than a human driver, so, with all of this in mind, you've now a lot more room on the roads. They will all be networked and be able to navigate the roads much more efficiently, being able to figure out, in real time, the best possible route for all cars, and completely eliminating human intervention.
I really do think the road will be filled with these tiny 1-2 seater cars that take up minimal space and are mostly used for short distances. On the highways and interstates, you'll have something similar to
this:https://c1.staticflickr.com/8/7150/6747 ... 1a32_b.jpg
Except it will be much better designed. Whenever one of these tiny one seater cars needs to go somewhere far or somewhere fast, they hop on the highway, link up to one of these 'carrier' vehicles, and then have this carrier vehicle take them farther and faster on the highways. When they are close to their destination, they will de-link themselves, and drive the remaining distance. This carrier vehicle could possible have two or even three 'stacks' of cars, which would take up even less space on the road.
So basically, if there is more demand on the roads, I think it's completely fine. We will come up with plenty of creative ways to use the existing road space effectively.
What I really wonder is how DFW will fare in this autonomous future. When autonomous vehicles do catch on, I would think we would be at an advantage since we have so much road space. I think we will find ways to speed up travel time as well, so sprawl may not be as big of a deal. Our sprawl (in my opinion) has hurt us in a lot of ways, but I'd like to think our expansive roads might eventually become an advantage in the future.