The self driving trucks are already on the road. They are doing long haul highway routes. The human driven trucks are used to move the trailers on local segments to and from the highway at each end.
U.S. Post Office Testing Driverless Trucks Between 2 Cities
Amazon is hauling cargo in self-driving trucks developed by Embark
U.S. Post Office Testing Driverless Trucks Between 2 Cities
Amazon is hauling cargo in self-driving trucks developed by Embark