Hyperloop - Vacuum tube train proposal by Elon Musk
On August 12, 2013, Elon Musk (CEO of Tesla Motors and SpaceX) unveiled a proposal for a high speed train system that would whisk passengers between San Francisco and Los Angeles in about 30 minutes. The system is best suited for trips of a few hundred miles, but not for really long range trips.
The system design uses steel tubes containing a partial vacuum (lower air resistance) within which electromagnetically-driven capsules are whisking by at 700 miles/hr. On top are more than enough solar panels to power the system.
It is an example of a Vactrain (vacuum tube train) system. Rather than use a full vacuum in the tubes, Musk envisions a very low atmospheric pressure. Why? Because it's a lot easier to maintain low pressure than it is to maintain zero atmosphere.