Well, one of the big points in favour of developing automatic vehicles is you don’t have to build extra infrastructure, or you build minimal infrastucture (like a network connection to traffic signals and information). You need a gradual transition to get there, you can’t bar the cars until you have dedicated lanes for them. No reason to get one if you can’t use it, no reason to build the dedicated lanes if nobody has them.

Probably the first generation will be semi-automatic. For example, highway only, driver has to get the car to and from the highway. Then perhaps doing major streets, etc. Possibly doing highway and “adapted” urban streets with data networking, more accurate positioning etc.

So there are no “arteries for self-driving vehicles” until quite a way into the program. But you don’t want to wall off lanes, you have to deal with the ablity to swerve or move to avoid broken down cars, human drivers, pedestrians, debris, potholes etc. All of which the grand challenge cars can do now.