If it's any kind of open track, it'll have problems with sonic booms. 400 miles in 30 minutes is 800 mph, a speed which exceeds the speed of sound at sea-level (~ 760mph). The neighbors aren't going to like that.
Hmm. Maybe it won't be a problem after all. The size of the sonic boom seems to correlate positively with the size of the wing surface. Since a track (or tube) based system wouldn't need much of a wing, it ought to have a pretty small boom.
However, I do want to point out that rifle shots are supersonic and are annoying to the neighbors, and they have no wings at all.
A friend has a rifle in 300 AAC Blackout. Subsonic ammo is far quieter than supersonic -- but you'd still want hearing protection. With a suppressor attached, it's quieter still -- you can fire it without wearing earplugs. But it's not "Hollywood quiet" - that's a movie myth.
The real issue is the safety issue. Shutting down a vehicle moving at 2500 feet/sec without subjecting the occupants to unhealthy G-forces is going to be rather difficult. But who knows, the human body can certainly withstand some pretty intense shock:
http://www.youtube.com/watch?v=s4tuvOer_GI
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[ 1.9 ms ] story [ 33.0 ms ] threadHowever, I do want to point out that rifle shots are supersonic and are annoying to the neighbors, and they have no wings at all.
https://news.ycombinator.com/item?id=6046943
He seems to verify that there will be "pods" 2m wide, so it sounds like this will be tunnel- or tube-based.