Hyperloop -- August 12, 2013

Elon Musk was not happy with the details of the California high speed rail project, so he started to think about an alternative, which he said at one time would be a "cross between a Concorde, a rail gun and an air hockey table."

Today he revealed his concept, an elevated pneumatic tube line, with the cars impelled by magnetic levitation and riding on a cushion of air.  He feels the cars could go from San Francisco to Los Angeles in 30 minutes.  He says that the system would not be practical for distances over 1000 miles.

It might work, although I don't think Musk took the power of NIMBYs into account.  

I thought about Alfred Ely Beach's Beach Pneumatic Subway, which he tested under Broadway, New York for some time after 1870.