In brief: Google's Waymo subsidiary has made plenty of progress with its self-driving car tech over the past few years. In October of 2018, the company's autonomous cars managed to rack up over 10 million miles of driving distance on public roads, and now, it's ready to begin offering fully-automated, safety driver-free rides to Phoenix residents.

Waymo has been testing its technology in Phoenix for quite a while now, but usually with a safety driver present -- this latest move represents the first fully-realized example of Level 4 autonomous tech in Google's fleet of minivans. Google said it was close to achieving this milestone earlier this month, and now the company has followed through.

"From our perspective at Waymo, a Level 4 vehicle is a vehicle in which you can put a rider who doesn't have a driver's license or vision and they could move from point A to point B," said Waymo CEO John Krafcik. "If you need a driver's license, you can't call it self-driving."

However, as confident as Waymo is in its ability to ensure drive safety, rider-only trips will be limited a relative handful of testers at first: a few hundred, to be more precise. Waymo will undoubtedly want to ensure the technology is working as intended before they start putting thousands upon thousands of riders in the passenger seat.

Rider-only trips are already underway, and if all goes well, Waymo and co. will begin scaling up the frequency of these trips until they fully replace supervised rides.

We look forward to covering Waymo's progress further in the future, and we'll be interested to see whether or not the company can expand its driver-free autonomous vehicle program to other states and cities across the US.