Shuttling passenger pods through low-friction tubes at close to the speed of sound is a vision that needs to clear numerous hurdles to become a reality, but add a 15-year-old technological concept to that vision and you suddenly have much more viable transport system. At least that's how Hyperloop Transportation Technologies sees it, announcing plans to float passenger modules over its tracks using passive magnetic levitation that will make the Hyperloop both cheaper and safer.

Passive magnetic levitation was developed by the physicist Richard Post at Lawrence Livermore National Labs (LLNL) in 2000. It is based on a particular arrangement of magnets and passive coils called a Halbach array, which was originally developed by Klaus Halbach at Lawrence Berkeley National Laboratory in the 1980's for use in particle accelerators.

Magnets in a Halbach array are placed in an alternating orientation, with each magnet at a right angle to those adjacent. This creates a very strong magnetic field below the array, while the magnetic field lines above the array cancel each other out.

Post figured that this could make for a passive alternative to maglev systems, which use superconducting magnets or powered electromagnets to function. He found that propelling this array over a track laden with coils of insulated wire, with each coil a closed circuit, created a levitating effect whereby the array is lifted above the track.

The physicist dubbed this system Inductrack, and in testing found it was able to lift a 22 kg (48.5 lb) vehicle above a 20-meter (66-ft) test track. This caught the attention of NASA, which then began to investigate the potential for the system to launch rockets into space with a view to cutting fuel costs. But despite its early promise, Inductrack never seemed to, well, really get off the ground.

Hyperloop Transportation Technologies (HTT), which is just one of the startups working to make the Hyperloop a reality, has been working with LLNL to develop and test passive magnetic levitation for its purpose over the past year. It has exclusively licensed the Inductrack system, and if it does work on a full-scale version of the Hyperloop, the system would require a whole lot less power (and money and infrastructure) to run.

But that's not the only advantage. Inductrack is claimed to be fail-safe, as the levitation is triggered through the movement of the array over the coils. This means that if there was a power failure, the pods would remain in the air and only touch the ground as they came to a halt.

HTT is far from alone in the race to get the Hyperloop up and running. Foe and fellow startup Hyperloop Technologies has built a test track in the Nevada desert, where it is holding a press event this week to showcase its technology (stay tuned to Gizmag for the upshot). SpaceX is also building a test track at its California facility and is holding a pod design competition later in the year.

You can get an overview of how HTT's version will work in the video below, which shows s snippet of actual test footage at the end.

Update May 13, 2016: This article has been updated to reflect the fact that Halbach arrays were developed at Lawrence Berkeley National Laboratory, not Lawrence Livermore National Labs as originally stated. Gizmag apologizes for the error.

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