https://secure.wikimedia.org/wikipedia/en/wiki/The_Roads_Mus...
Unfortunately, fast-moving underground moving sidewalks sound like an incredible waste of energy.
Would be nice to expend only the energy required to move people and things and anything needed to take care of them (safety systems)
I still think technology is winning the resource depletion race, even if we ignore the fact that it's really starting to look like oil production isn't actually near the end of its road yet. And if we don't ignore that, the likelihood that gas (or more broadly "energy") will just be "too expensive" for people to want to jaunt about anytime in the next 20 years seems to be decreasing rather than increasing. A great deal of our current apparent shortages of various things are 100% self-imposed.
Buses in SF run totally with overhead wires. You see the drivers having to reconnect to them when they pop out.
Use the commute time to telecommute and shorten (or extend!) your in-office work day, or spend it pursuing solitary leisure activities and work a normal-length day at the office.
This would be awesome.