Elon Musk yesterday revealed the details of his concept for a super-speed ground transport between LA and San Francisco.

The thing would take the form of an elevated “rail” line comprised of a partially evacuated tube through which passenger pods would be accelerated by the magnetic field produced by induction motors.

The system would drive the pods up to 760 miles per hour, or about nine-tenths the speed of sound. Travel between the two big California cities could be possible within half an hour.

Check out my summary and some pictures in my piece for Popular Mechanics.

Read the 57-page treatment produced by Musk with the help of his engineers at Tesla Motors and SpaceX at http://www.spacex.com/sites/spacex/files/hyperloop_alpha-20130812.pdf.

Musk estimates the cost of the system to be $6 billion dollars—quite a bit less than the nearly $70 billion estimated price tag for the California high speed rail project. That system is expected to hit a top speed of a bit over 200 miles per hour.

Musk told me and other reporters in a conference call yesterday that he’s thinking about building a demonstration line, perhaps at SpaceX’s West Texas rocket proving ground, but that he’d be delighted if someone else would take up the project.

As for building the complete system, there are more hurtles than merely the technical and financial ones (which are formidable in themselves). The State of California and all of its competing interests would have to be on board. As the Hyperloop would be a clear competitor to the already-approved high speed rail project, that seems unlikely at the moment.

Still, there is a recent precedent for an ambitious privately built transportation system replacing one run by the government: the SpaceX Falcon 9 rocket and Dragon spaceship.