Elon Musk to unveil underground tunnel, transport cars

Tech entrepreneur Elon Musk is set to unveil an underground transportation tunnel today that could move people faster than subways.

Musk also plans to show off the autonomous cars that will carry people through the test tunnel, which runs about 2 miles under the streets of Hawthorne, California, Musk's SpaceX headquarters. He's also planning to unveil elevators he says will bring users' own cars from street level to the tunnel.

Today's reveal comes almost two years to the day since Musk announced on Twitter that "traffic is driving me nuts" and he was "going to build a tunnel boring machine and just start digging."