Alphabet’s self-driving car unit Waymo today took a huge step toward launching its first public self-driving taxi service.

Waymo has been testing a driverless car service in Phoenix for a while already, but today the company officially lifted the lid on its first commercial service that riders can actually pay for.

Waymo One, as the service is called, will work much like Uber and other popular ride-hailing apps. After Waymo One gives you a price estimate based on your starting and end points, you can beckon a car that will transport you from A to B.

However, Waymo One isn’t yet available for everyone. Initially, only riders who were involved in the early stages of the trial program will have access, though plans are afoot to extend the service to more people in the future.

Those already accepted into the program will be able to bring along two adults and a child.

Google first started testing autonomous cars on San Francisco roads as part of a stealth project in 2009. The unit was rebranded to Waymo in 2016 and spun out as an Alphabet subsidiary led by John Krafcik, former president and CEO of Hyundai North America.

Waymo recently claimed 10 million self-driven miles on public roads after doubling the number of miles in just eight months.

Road to launch

Waymo One cars will be available round the clock in the Metro Phoenix area. It is worth noting that although the cars are fully self-driving, a human “driver” will be present at first. Waymo isn’t really pitching these as “safety” drivers, since it doesn’t anticipate their having to take control — it’s more about peace of mind for people apprehensive about stepping inside a driverless vehicle.

The company explained: “Waymo-trained drivers will be riding along to supervise our vehicles for riders’ comfort and convenience.”

Similar to Uber and other ride-hailing services, you will also be able to request support from within the app and review the ride afterwards.

A number of public autonomous taxi trials have taken place over the past couple of years. However, the launch of a fully commercial service in the U.S. by Waymo — one of the autonomous vehicle sector’s leading players — represents a notable milestone for the fledgling industry.