Comment by jaredklewis

I understand those benefits, and think they are marvelous, but also very expensive.

American cities are already spending more than they can afford on road maintenance. Are these underground trains going to be cheaper than above ground roads? Public money for this doesn't seem all that likely.

Here in Tokyo, the Yamanote above ground train serves a million riders daily. Costs a couple dollars to go 10km. The boring concept looks much more expensive than that, as it is underground, but those costs are spread out over many fewer people. Private money seems hard, too.