Then there's Tesla Motors co-founder Elon Musk's new idea called the Hyperloop, which he revealed today: an elevated, solar-powered train-in-a-tube that could whisk riders at supersonic speeds up to 900 miles. It sounds fantastic, and according to Musk could be built for less than a comparable magnetic-levitation train — roughly $6 billion for a Los Angeles-to-San Franciso route that would cut travel time to 30 minutes for a $20 ticket.
The proposal from Musk — a 57-page paper full of aerodynamic engineering concepts and economic discussion points — has as much connection to reality as a comic book at the moment.
Musk describes the Hyperloop as essentially a solar-powered version of the pneumatic tubes once common in offices and drive-through bank branches. By riding on pressurized air, with a compressor fan at the front of the capsules, the vehicles could accelerate up to 760 mph without the disruptive sonic booms supersonic aircraft produce. And despite the speeds, Musk says the accelerations would be limited to no more than what passengers face today: "It would feel like you were riding in an airplane, like you're riding in a cushion of air."
To survive in California's earthquake-prone geography, the Hyperloop would be built on pillars designed to cushion the tube from tremors, a system that Musk contends would be safer than trains today. In fact, Musk contends if the Hyperloop tubes were coated in solar panels, they would generate more energy than the system uses and should be better in every dimension — cheaper, safer, more energy efficient and pleasant to travel in — than the current alternatives.
As for the economics, by Musk's calculations the machinery inside the tube is relatively cheap — about $60 million or so. While the tube itself would cost $6 billion to build along Interstate 5 in California, if the Hyperloop ran at regular intervals it could pay for itself with passenger fares of $20 a ride over 20 years, at several million passengers a year. Musk contends the Hyperloop would work best for distances less than 900 miles; longer than that, airplanes make better sense.