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Topic: compressed-air transit

A recovery vehicle moves a sled down a track after a test of a Hyperloop One propulsion system, Wednesday, May 11, 2016, in North Las Vegas, Nev. The startup company opened its test site outside of Las Vegas for the first public demonstration of technology for a super-speed, tube based transportation system. (AP Photo/John Locher) (AP)

In defense of the hyperloop

Eric Holthaus - Grist