The speed of sound is 767mph, while Hyperloop would travel at 760mph (1,223km/h). Musk had previously suggested a functional Hyperloop system in the US could cost $6 billion (£4 billion), although others suggest the figure will be much higher

Hyperloop Technologies have been building a test track to demonstrate their version of the transport technology just outside Las Vegas (tubing for the test system pictured)

He also operates his own foundation focusing on education, clean energy and children's health.

Meanwhile, another startup that has picked up the Hyperloop gauntlet announced that its design is incorporating passive magnetic levitation originally conceived by a team at Lawrence Livermore National Laboratory.

'Utilizing a passive levitation system will eliminate the need for power stations along the Hyperloop track, which makes this system the most suitable for the application and will keep construction costs low,' Hyperloop Transportation Technologies chief operating officer Bibop Gresta said in a statement.

'From a safety aspect, the system has huge advantages, levitation occurs purely through movement, therefore if any type of power failure occurs, Hyperloop pods would continue to levitate and only after reaching minimal speeds touch the ground.'

After Musk published a white paper describing a futuristic mode of super high-speed rail transit, Hyperloop Transportation 'rose to the challenge,' it said.