Driverless semis could be months away

On a sunny morning in December, an 18-wheeler will pull into a truck depot in Palmer, Texas, just south of Dallas. The driver will step out of the cab and help transfer his trailer to a second rig outfitted with powerful sensors.

This second truck will head south on Interstate 45 toward Houston. It will move cautiously, mostly cruising in the right lane at 65 mph despite the 75 mph speed limit.

After three and a half hours, the truck will exit the freeway in Greenpoint, a neighborhood in the north of Houston. It will proceed to a second truck depot, where the trailer will again be transferred to a new rig. A different driver will get in and haul the cargo to its final destination a few miles away.