My specific point was about how to address a coming traffic crisis, sorry if that was unclear. I'm suggesting that 90% of traffic will be unaccompanied "stuff" and that moving it underground will free up traffic for people above ground. So either way, we're both talking about getting from A to B more quickly.

I'm sure there will be a need that arises for more tunnels for people, too. But I think the place to START and allocate resources is tunnels for stuff since that's where the problem will come from.

I think that we should consider total underground transportation as a design goal. Even if we reduce, say, the highway traffic by 90%, the remaining 10% will still deal with weather conditions, peak usage times, and bottlenecks such as construction or traffic accidents.

There are plenty of reasons to move people underground rather than above, along with goods. My personal interest in this is that a scalable 100% underground transportation system would make for a better model for life on the moon or Mars than anything we currently have on Earth.

Besides, traveling underground doesn’t have to be a dreary, dystopian experience. If we moved people in rectangular structures resembling elevators, we could cover the floor and ceilings with LCD screens, so instead of feeling like you’re inside an elevator, you could set the screens to show a panorama of the city you’re in, or the Swiss Alps, or if you throw a camera and microphone in there, you could attend a meeting while you’re on your way to that meeting.

Even if we get goods moving off the roads, personal transportation still has enormous costs. Just ask any American who has had to choose between paying high rent to live close to work, or buying a car to commute further away from their lower-rent home.