(Bloomberg) -- Elon Musk provided a few tantalizing details about his Boring Co.’s soon-to-open Los Angeles tunnel, indicating that it will work with modified autonomous cars.

“Boring Company product launch on Dec. 18,” he tweeted on Thursday. “More than a tunnel opening. Will include modded but fully road legal autonomous transport cars & ground to tunnel car elevators.”

The timing represents a delay of slightly more than a week from the Dec. 10 date Musk had previously set for the opening of the long-awaited test tunnel. Elevators to transport the cars are at both ends of the mile-long tunnel in Hawthorne, California, near the headquarters of his Space Exploration Technologies Corp. rocket business, said a person familiar with the project who asked not to be identified because the details are private.

Musk’s idea for a network of tunnels to beat Los Angeles traffic took shape in December 2016, when he tweeted “Am going to build a tunnel boring machine and just start digging.” Two years later, he has projects underway in Los Angeles, Chicago, and Washington, although a proposal to build a separate test tunnel in West Los Angeles was scrapped last month.

To contact the author of this story: Sarah McBride in San Francisco at smcbride24@bloomberg.net

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