[TeMPOraL]

Expensive, single-purpose hardwired tracks that make it much more efficient for the whole vehicle to travel. 500 autonomous vehicles all carry engines, batteries, lights and a lot of stuff that is not needed when those car are all traveling together, but wastes energy anyway. Also, the price tag of those single-purpose tracks is amortized by all the millions of "cars" that travel on them.

[CamperBob2]

Something you're missing is that autonomous cars can bring an end to the era where everyone feels compelled to own at least one car, if not two. Most cars spend 1-2 hours per day on the road and 22-23 hours parked somewhere. With appropriate resource planning, a network of autonomous cars can probably serve as many people as our current urban highway systems do with 10% of the vehicles. And you can rest assured none of them are going to be burning gasoline.

People don't understand just how insanely different things are going to look in another couple of decades. Trains make sense if, and only if, everything stays exactly the same.

[TeMPOraL]

I am first to hope for the autonomous cars and ending car ownership, because IMO the current road situation is absolutely ridiculous (In the meantime, someone would please train drivers like they do train airline pilots? I.e. beat the stupidity out of them with enough training.). A PRT network made out of autonomous electric cars would be something absolutely wonderful... in a city.

But between the cities, you still have tons of cars going together, in a line, all the time. There is no flexibility here, almost everyone is going the same direction for most of the way. I don't see how even autonomous electric cars could beat trains on that. I think that the best way for the future is bullet trains/hyperloop connecting the large cities, and PRT within the city. I'm open to math that shows otherwise though.