FOR years Elon Musk, a South African-born tech entrepreneur, has been telling anyone who will listen that the future of travel is the hyperloop. (Although he thinks it might also be driverless cars. Or perhaps affordable space travel.) Dubai may be about to test the limits of Mr Musk’s imagination. The hyperloop is a train that moves along a tube that is kept at a thousandth of the normal atmospheric pressure at sea level. Because air resistance is one of the biggest obstacles to high-speed travel, all but eliminating it means that hair-raising velocity becomes possible. The proposed technology could shunt passengers along tunnels at perhaps 745mph, which is faster than a jet plane.

On November 8th, Hyperloop One, one of the firms developing the technology, signed an agreement with the Dubai Roads and Transport Authority to test the feasibility of running a service to Abu Dhabi. The journey, which currently takes two hours by car, would be cut to just 12 minutes. Rob Lloyd, the boss of Hyperloop One, reckons that “from a technological point of view, we could have a Hyperloop One system built in the UAE in the next five years”.

That may be optimistic for several reasons. One is money. No one involved has released an estimate as to how much the Dubai project might cost, but Mr Musk has said in the past that a line could be built between Los Angeles and San Francisco for $6bn. Many observers think that implausible. If the costs ran wild, even Dubai, with its famed largesse, would baulk.

Then there is the issue of safety. A lot of tests will have to be run before it is licensed. And just as important is passenger comfort. As we explained when Mr Musk first unveiled his plans in 2013:

Hyperloop proposes to subject its passengers to fairly severe accelerations as it goes around corners and up hills; from the published numbers those accelerations seem greatly to exceed the rules of thumb used to design ordinary railways. Riding a rollercoaster from San Francisco to Los Angeles may not be a universally popular proposition.

If the ride proves sickening, then no amount of time saving will encourage passengers to strap themselves in. For this reason a test route across the Arabian desert would be a sensible place to start. With few obstacles to bypass, there will be less need for nausea-inducing bends.

For all the difficulties it must overcome, there does seem to be enough investor interest in Hyperloop One to suggest the concept deserves to be taken seriously. Indeed, earlier this year the system had its first, tentative tests in Nevada. It may take more than five years to realise, but this is no mere pipe dream.