[Johnny555]

But, not coincidentally, those areas are the same areas where freeways are at capacity and would benefit from running 4 passenger self-driving cars at 1 second headways.

Self driving cars work well with railroads -- the cars can get passengers from their lower density neighborhoods to the rail stations, and rail can take the passengers to the urban centers where their jobs are. It makes little sense for a self-driving car to take a worker from his suburban home all the way to the crowded urban center where his car either needs to find someplace to park, or join thousands of other cars looking for someone else to ride until it's time to go home.

[vidarh]

That's the best part, I think, with self driving services: Coupled with other modes of transport, if we know the start and end points, we can optimize public transport accordingly, and in the meantime your car can take you to the optimal station and tell you which platform to go to and where you'll get picked up for the final leg of your journey.

You can also then optimize to drop people off at stations they might not otherwise pick if traffic makes it more sensible, or tell them to get off a station early/late and pick them up there if it helps the overall journey.

Over the long run it may even fundamentally alter construction of new lines, in that there may be more optimal location of station placements for stations e.g. feeding commuters when you have detailed data on the precise journeys.