As promised back in January, Elon Musk has unveiled his plans for a high-speed tunnel underneath LA that will help with severe traffic congestion.
The prototype tunnel is only a mile long, but that's enough distance to give a flavour of what the project, run by Musk's Boring Company (because it bores holes, y'see) is about.
Originally envisaged with Futurama-style travel pods, the tunnel will now use people's cars to move them at high speed under the city. Kind of like the Tube, but with cars instead of carriages.
It all sounds a bit terrifying, though. You sit in your electric car (which you'll need to modify for the system, at a cost of about £200) which is automatically lowered down into the tunnel. Then it locks into the tunnel's track and the stabilising wheels keep it from flying off course as it accelerates up to 150mph. Yeesh, that's going to be some major car sickness.
For comparison, Rita Queen of Speed at Alton Towers goes up to about 60mph, and Stealth at Thorpe Park is 80mph.
Musk tells the BBC:
"The profound breakthrough is very simple: it's the ability to turn a normal car into a passively stable vehicle by adding the deployable tracking wheels, stabilising wheels, so that it can travel at high speed through a small tunnel.
The way the loop will work is you will have main arteries that are travelling at 150mph and when you want to go to an exit, you will have an off ramp.
So you can travel the vast majority of your journey without stopping at 150mph and only slow down when you get to your exit, and then automatically transfer from one tunnel to another. It's like a 3D highway system underground basically."
The Beeb's test rider describes the experience as "almost a white knuckle ride" at just 49mph, but apparently it'll be a lot less bumpy when it launches for real at three times the speed.
The test ride used a modified Tesla Model X, of course, and the tunnel cost about $10m (£8m). Musk says using a more traditional method of tunnel building would have cost up to $1bn, but he's not exactly known for understatement.
Eventually, the system is envisaged to run under the whole of LA to ease traffic congestion, but the one-mile test track under Hawthorne is a long way from that yet. Still, it's good to see it in action -- more innovation in transport is sorely needed, and if it takes an enigmatic billionaire to get it done, so be it.