Hyperloop, once trumpeted by Elon Musk, involves capsules floating on magnetic fields zipping at speeds of arund 700 kph (435 mph) Its advocates tout it as far more efficient than short haul flights, high-speed rail and freight trucks. But since Musk unveiled the concept that he said could shuttle passengers the nearly 400 miles (645 kilometers) between Los Angeles and San Francisco in 30 minutes, it has progressed at a much slower pace from the drawing board toward the real world.