In an appearance at the TED conference in Vancouver, Musk showed off a new video visualization of electric skates transporting cars in a narrow tunnel, then raising them back to street level in a space as small as two parking spaces. Inside the tunnels, Musk said cars could travel as fast as 200 kilometers per hour (roughly 130 MPH).
"You should be able to go from say Westwood to LAX in 5-6 minutes," the Tesla and SpaceX founder said, adding he is spending only 2-3% on the tunnel effort.
The challenges: Permissions and cost, and cities would have to approve a network of tunnels. Even if they do, conventional tunnel requirements are exceedingly costly. Musk cited as the example of a recent 2.5-mile LA subway extension that cost $2.5 billion. Musk aims to cut that through narrower tunnels and other moves.