Jarret Walker:

 We’re starting to see professional reports echoing long-standing concerns about how driverless cars will affect our cities. This new one from KPMG in particular, is getting a lot of press. It’s actually a focus group about the transport desires of different generations, but it confirms the thought experiments that many of us have already been laying out for a while.
 Much depends on whether these cars are owned or spontaneously hired like taxis. A taxi model is definitely better in its congestion impacts, but that doesn’t mean it will happen. The ownership model is closer to the status quo, and the status quo always has enormous power. Driverless taxis will not always be available on demand, especially in suburban and rural areas, so a legitimate fear of being stranded will make people in those areas prefer the security of having a car just for them. And of course, that’s just the effect of rational concerns about relying on taxis. Less rational desires for car ownership, as an expression of identity or symbol of liberty, will also not vanish overnight.
 This leads to a nightmare scenario that University of Washington’s Mark Hollenbeck laid out in our recent Seattle Times panel. Paraphrasing Mark: A suburban father rides his driverless car to work, maybe dropping his daughter off a at school. But rather than park the car downtown, he simply tells it to drive back home to his house in the suburbs. During the day, it runs some other errands for his family. At 3 pm, it goes to the school to bring his daughter home or chauffeur her to after-school activities. Then it’s time for it to drive back into the city to pick up Dad from work. But then, on a lark, Dad decides to go shopping at a downtown department store after work, so he tells his car to just circle the block for an hour while he shops, before finally hailing it to go home.