Elon Musk says he's worked out how to get rid of traffic jams - without making us give up our cars.
The billionaire inventor is proposing an underground network of high speed tunnels. He's built a tunnel in Los Angeles to show how it would work.
A few years ago, Musk decided he'd had enough of LA gridlock.
"Either we try something new, or we will be stuck in traffic hell for the rest of our lives," he told CBS.
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His idea? Electric cars use street-level elevators to drop down into the tunnels, and technology in the vehicles ensures they don't run into each other - despite travelling at speeds of more than 200km/h.
"Tunnels are, in my view, the only solution to urban congestion."
Musk formed The Boring Company and started digging the test tunnel in Hawthorne about a year ago.
While modern subway tunnels in LA cost around US$900m (NZ$1.3bn) per mile, Musk says he built his for about US$10m (NZ$14m). His eventual goal is to move 4000 cars every hour.
The prototype tunnel is just 3.7 metres in diameter, but Musk says there's no risk of it collapsing in earthquake country.
"Our tunnels are designed to the highest California seismic standards," he told CBS.
"At this point, I'm confident this can revolutionise cities and get rid of soul-destroying traffic."