Elon Musk, often referred to as the real life Tony Stark, has developed plans for the Hyperloop, a vehicle that could transport people from Los Angeles to San Francisco in 30 minutes. It would cost $6-$10 billion to build. 

From The Wall Street Journal:

Mr. Musk’s plans call for a pair of steel tubes running side by side on elevated pylons. Inside the tubes, air compressors would create a low-pressure environment, though not a vacuum, which would be harder to maintain over long distances.

Inside the tubes, capsules would be propelled forward by an electric induction motor, Mr. Musk said, an invention he said dated to the days of electricity pioneer Nikola Tesla. In his system, electric pulses travel the length of the tubes; a magnetized blade on the base of each pod would be propelled forward by the pulses of energy, which Mr. Musk said could come from solar panels on the tops of the tubes.

Pods would travel at about 760 miles an hour. He said it is ideal for cities less than 900 miles apart; for further distances, supersonic planes are more efficient, he said.

The Hyperloop could follow the route of Interstate 5. This would eliminate the need to acquire land or property and cut down on some criticism of the project. Musk claimed his idea is better and costs much less than what the state is doing right now.

This is very different from the trains the California High-Speed Rail Authority are currently working on. These will link San Francisco and Los Angeles and they want to expand it from San Diego to Sacramento by 2029. Passengers would arrive in three hours, which is longer than the Hyperloop, but it is faster than the regular trains in the US. This project is estimated at $68.4 billion.