So, when is he going to build Space Cannon One?
Seems more logical as a space launch facility (Hyperlaunch?) than fast transport. Just get rid of the curves, point it up a mountain, and stick a relatively weak membrane over the end to hold the internal vacuum until the launch vehicle punches through it. Of course, the velocity will have to go up a bit...
I hear someone in the middle east tried a low tech version of this a while ago, but had trouble sourcing components....