Tyler Cowen:

The standard story is that traffic deaths will dwindle, cities will spread out magnificently, and you’ll all be reading MR on your morning commute rather than fighting the traffic. Maybe so, but what other options are at least worth considering, if only out of contrarian orneriness?:
 1. Driverless cars are not actually much better than the really good German streetcar systems. Those come closer to door-to-door service than many people realize, and of course they have lower energy and congestion costs.
 2. The need for exact mapping of streets will restrict driverless vehicles to well-known, well-trodden paths, much like bus lines. There is nothing wrong with that, but ultimately it won’t do more than save the cost of the bus driver. Or worse yet — some automobile lanes may be turned over to municipal driverless vehicles in a way which makes traffic problems worse. It will end up as a way to push cars out of the picture, without building up the broader mass transit network very much.