Billionaire technologist Elon Musk has revealed details of his new Hyperloop project, a 'fifth mode' of transport that could someday join planes, trains, cars and boats as a major transit system.
Detailed today in a 57-page document, the Hyperloop would take around seven to 10 years to build, costing around US$6 billion.
That's not pocket change, but it's a fraction of the $68 billion cost of a new train line planned by the state of California - a project that Musk says is too expensive, too slow and too wasteful.
Musk's plan reads like a science-fiction story, proposing giant above-ground tubes spanning the space between neighbouring cities, propelling passenger capsules at speeds of up to 1280km/h.
Musk and his team believe that his $6 billion budget would see a Hyperloop built between San Francisco and Los Angeles, transporting over seven million people each year.
Holding 28 passengers each, the capsules would depart every 30 seconds, crossing the 615km distance in just 30 minutes.
Even ignoring the supposed cost benefits of the technology, that time compares favourably to current travel times for the trip: 5.5 hours by car, 1.5 hours by plane - and nearly three hours on the state's proposed train line.
Riding on a cushion of air inside the tubes, the capsules would be propelled by electric motors similar to those powering the Tesla Model S - one of Musk's other babies.
Importantly - and unsurprisingly, given Musk's green-focused vision for the future - the Hyperloop would be solar powered, drawing energy from panels mounted atop the tubes.
The Hyperloop would be safer, faster, less expensive and more convenient than the state's planned train line, Musk wrote on his blog.
It remains to be seen if the project will get the crucial government approval it needs, and Musk has also been clear that he does not have the time to manage the project himself. At least, not all of it.
"I've come around a little bit on my thinking here," he told press in California this week.
"Maybe I could do the beginning bit... and then hand it over to somebody else," he said.
It's an ambitious project, but with Musk's previous projects - PayPal, Tesla Motors and SpaceX - all boasting successful launches (literally, in SpaceX's case), the Hyperloop may not be out of reach.