Google has long stated its intent to skip driver-assist systems and go directly to fully autonomous driving.
The company's next goal will be to expand self-driving services to a 600-square mile radius around Phoenix.
"Over the next few months, we'll be inviting members of the public to take trips in our fully self-driving vehicles", Waymo said.
Waymo says they prepared for this testing after putting vehicles to the test since 2009, having driven 3.5 million miles autonomously on public roads in 20 different US cities since the beginning. It will be good for the old and the young, the blind and blotto, and save lives in the process, by starting to remove fallible humanity from the highway equation, boosters say. But instead of being in the front seat, that employee will likely sit behind the driver's seat.
"This demonstrates Waymo's confidence in the ability of these vehicles to function at least in this environment", Abuelsamid said.
The company began testing self-driving vehicles in Chandler in 2016.
Waymo wouldn't say how many vehicles will be in the initial test or exactly how wide an area it will cover.
Previously road tests have taken place with a person in the driving seat ready to take the wheel.
This is all possible in part because Arizona hasn't bothered slapping autonomous cars with heavy regulations in the manner of states like NY, which has allowed - appropriately, considering the location - a "Wild West" approach to testing. It has a fleet of 100 autonomous vans in Phoenix, with plans to add 500. That type of system is actually stipulated by regulators in most areas where autonomous testing is allowed on public roads, but as the technology matures, rules are changing.
The brain-bending, potentially earth-moving technology that allows self-driving cars to drive themselves has generally come with an asterisk - in the form of an old-fashioned flesh-and-blood driver sitting behind the wheel, just in case.
At first, those passengers will be accompanied in the back seat by a Waymo employee, but eventually they will travel alone, although they will be able to hit a button to stop the vehicle. The stakes are so high that Waymo is now suing ride-hailing company Uber, alleging that one of its former managers stole its trade secrets and took them with him when he joined Uber in 2016 as part of an elaborate scheme. The company also wasn't available to comment on whether Waymo employees will be able to remotely terminate a ride.