To many, that might seem a frightening idea, even at a time when a few dozen of Google's driverless cars are cruising city streets in California, Texas, Washington and Arizona.

But Anthony Levandowski, a robot-loving engineer who helped steer Google's self-driving technology, is convinced autonomous big rigs will be the next big thing on the road to a safer transportation system.

Levandowski left Google earlier this year to pursue his vision at Otto, a San Francisco startup the he co-founded with two other former Google employees, Lior Ron and Don Burnette, and another robotics expert, Claire Delaunay.

Otto is aiming to equip trucks with software, sensors, lasers and cameras so they eventually will be able to navigate the more than 220,000 miles of U.S. highways on their own, while a human driver naps in the back of the cab or handles other tasks.

For now, the robot truckers would only take control on the highways, leaving humans to handle the tougher task of wending through city streets. The idea is similar to the automated pilots that fly jets at high altitudes while leaving the takeoffs and landings to humans.

"Our goal is to make trucks drive as humanly as possible, but with the reliability of machines," Levandowski says.