I realize the costs would be high, but would there be a way to embed some information in/near the roadway that would assist the onboard systems? I think there might be some advantages in making the road smarter in addition to the car.
I have no doubt that smarter roads are in our future, but they pose too high of a price for wide spread adoption of autonomous vehicles at the outset.
I really don't think it would be that expensive, at least along Interstates and major highways, to embed a trace wire to help guide self driving cars. (At least, during regular maintenance and new construction- tearing up roads to add it would obviously be expensive).