(Mary Sperling) claimed her car from the robopark, guided it up the ramp and set the controls for the North Shore. The car waited for a break in the traffic, then dived into the high-speed stream and hurried north. Mary settled back for a nap….awakened by the jangle of the emergency alarm and by the speedster slowing to a stop… “All cars resume local control….” Methuselah's Children, Robert A Heinlein, (1941) or 1958.With autonomous or even semi-autonomous cars in 120mph+ pelotons on existing freeways and Musk 120mph skates in tunnels in LA, whole metro areas are sprawlsville. The American life style will not be changed to urban living. Ford, General Motors, and all the rest will still be around in 2100 promoting sprawl.
The car is the most important surviving public status symbol, and Americans at least are not going to give that up. They will drive less especially locally but providing rides between urban nodes will still be an important status indicator. Cities, especially new cities, will evolve out of the suburbs with high density urban nodes around regional amenities with complete urban services, restaurants, service establishments and high density housing at all price points for those who choose to live and possibly work in an urban node.
The majority of the population will still be economically and ethnically segregated in single family homes and low density apartments in the suburbs, exurbs and now dead rural towns. The current pattern for office commercial segregated in suburban campuses will continue for the foreseeable future. Even working class cars will be high speed semi-autonomous and urban nodes will still require high density autonomous parking for residents and visitors.
Freeways will evolve to narrower lanes restricted to autonomous vehicles, with high speed lanes running in pelotons for efficiency and throughput. Current freeways of three lanes or more with a breakdown lane in the center will in the near future convert to two or more high speed lanes, one transition lane and leave one wide lane with a breakdown lane for non-autonomous cars at existing speed limits and entrance and exit.
Autonomous cars will park in high density parking lots on floors limited to small SUVs by floor spacing, served by elevators. Garages for autonomous vehicles only will be constructed over a major intersection with an existing freeway which is already served by transit and close to developed commercial or urban centers. The garage may be built over the freeway. Pedestrian and bicycle access is over the existing sidewalk space on the cross street and transit access over a lane of the cross street. Cars will enter from freeway access ramps to car lanes inside the garage next to the pedestrian/bikeway. Driverless autonomous cabs would be available at the freeway nodes for those needing them.
See also http://jcarlinsv.blogspot.com/2017/05/autonomous-cars-and-cities.html