So somehow instead of working tonight I found myself reading through the Hyperloop plans from Elon Musk. Basically it's a very-low-pressure, but not true vacuum, steel tube held up on pylons from LA to San Francisco. Linear accelerators (magnets) push cars through the tube by acting on aluminium blades on the bottom of the cars. The secret sauce, as it were, is to have a big electric fan on the front of the cars that sucks any air stuck in front of the car through an exhaust tube (and into a storage chamber). There's actually a lot of extra space around the cars too so that air can escape around the sides. Instead of using costly mag-lev to keep them out of contact with the edges of the tube, the cars will use an air-hockey-style "float on a cushion of air" mechanism.
I can't comment on the engineering; it's coming from Musk, so one would expect that it's not horrifically naive. Things to look into further:
- The cost projections feel more like a back-of-the-napkin guestimate than a budget, but that's fine, even if it's off by a factor of 10 it wouldn't be a horrifically over-priced project
- Some of the people operations seem a bit idealized; you have a commuter technology that takes 35 minutes pretty precisely and everyone needs to get to work at 09:00, how many people need to be in the tube at 08:20? Sure, you can just get employers not to be dumb, but how often does that happen?
- Will we really get fast access with strong security during the rush hour?
- 350 miles of solar cells might not happen with our current production capacity at a reasonable price...
- the "we'll stop everything and then crawl along if there's a problem" safety approach might not be practical if we only have one of these things on every corridor, so maybe we'll wind up with 3 tubes on every pylon or 4?
- I won't get into "how do we protect this from the deranged"
- There would need to be alternate solutions for power in northern/cloudy climates, likely a grid feed, which means we'd likely need to dial up the nuclear reactors a bit or burn more coal, or whatever we're doing these days.
Thing is, none of those details are a big deal. Instead of considering the project today, consider the idea in 20 years. With proper advances in materials science, battery, and motor technologies you would expect significant savings to become available. If we were to have a nation-wide network of core (straight) transport tubes you would start to see commuting from Toronto to New York as reasonable (800km, ~40 minutes, which would be reasonable if you could breeze through security in a couple of minutes).
Even comparatively very long trips, such as hopping down to Disneyworld (2000km, ~2 hours) aren't unreasonable, though Musk tells us he sees that as better dealt with by planes. I'll ignore the issue of needing greater weight in the car for long trips with some hand-waving about improvements in materials and batteries as noted above. (Note that current commercial planes cruise around 800km/hour, vs. 1200/hour for the proposed system, he's not talking about our current planes being a better choice, but supersonic suborbitals).
All in all, not a waste of an evening to read through it.