you still need the infrastructure costs, the location of the infrastructure just changes.
you can discuss costs all day, but aside from a few specific locales, infrastructure costs should be cheaper when weather, nature, and human wear & tear are removed. (as far as the human factor, I mean aside from vandalism... the general indifference people and corporations have to the state of the property they drive on. so if the transport is automated, it removes a good deal of potential wear & tear)