The bright blue trucks in Waymo's Atlanta pilot will still have back-up drivers in the cabs to monitor systems and take control if needed.
The firm said that the software used to drive the big trucks is the same as that which drives the company's cars; the lorries also use the same suite of sensors that power Waymo's self-driving minivan. In the pilot, Waymo will integrate its technology into the operations of shippers and carriers with their network of factories, distribution centres, ports and terminals.
Waymo, the former Google self-driving project that spun out to become a business under parent company Alphabet, is scaling up.
"Our software is learning to drive big rigs in much the same way a human driver would after years of driving passenger cars", the company wrote. Although the basic principles of driving remain the same, driving a truck that's loaded down with cargo is trickier due to its size and different ways of handling.
Both moves are only the latest steps in the advancement of self-driving vehicle technology. "In short, our near-decade of experience with passenger vehicles has given us a head start in trucking".
Tesla, of course, recently announced an all-electric semi truck with limited self-driving capabilities. Last week, Uber announced that its autonomous trucks have been operating in Arizona for a couple months now.
Autonomous-vehicle technology has been touted as having potential to save fuel, ease congestion, and make transportation safer.
The announcement comes days after rival Uber said its fleet of self-driving trucks was in use in Arizona.
USA states set their own rules for roads, and a handful have passed laws allowing self-driving vehicles.
Thus far, Waymo seems to have focused mostly on applying its self-driving technology to the ride-hailing market. A Waymo spokeswoman declined to say how many trucks will be tested.