[cmarschner]

Agree with the first point - if the final goal is to move people around at low costs in terms of construction/maintenance, land use, and environmental factors, the low ratio of "transported human" vs. "transported metal" makes cars the worst of all choices. This can also only alleviated for so long by making roads more congested in a more efficient way. In the end, roads are still a massive waste.

Some of your other points make too many assumptions of maintaining a status quo. E.g. automated cars will make sharing schemes more feasible. You can either hop on an uber-like car to get home, or lease your car out in the 96% of the time it sits idle.

Unfortunately (depending on the right price) I think this will make car travel more attractive compared to other forms of transport. One can think of a lot of sharing schemes - individual cars, minibuses, or large busses like we have today - with different price points. Overall costs of motorized travel is likely to fall. So I would think that overall we will see that vehicle use will go up (at the expense of walking on foot, for example) and use of parking lots will go down. In fact if traffic wasn't as cyclic as it is one wouldn't need any parking lots at all.

Also, if you can really get to the 130 or so MPH in the tunnel, then travel time will not be such an issue.

The main fallacy of the whole initiative, however, is that it is based on status quo of the structure of cities. Compare the urban sprawl of a post-WW2 US city with those of a medieval town. The main difference was that travel was slower, and faster travel was incredibly expensive (mostly unreachable due to lacking technology). It led to a much more efficient use of resources. If anything we need to redesign our cities based on these old principles in order to reduce overall resource consumption.