AFTER NEARLY A decade of working on self-driving cars in private, Google is finally ready to take the public for a ride. Its autonomous spin-off, Waymo is adding 500 modified Chrysler Pacifica minivans to the 100 it already has on the roads of Phoenix, Arizona, and has invited locals to sign up for free rides to school, work, soccer practice, or anywhere else they need to go.

Waymo likely has the most sophisticated driving tech in this increasingly crowded field. After three million miles of on-road testing, the cars can drive thousands of miles without human intervention. But delivering autonomy take more than the right algorithms.

With its Phoenix launch, Waymo starts working on another facet of the problem: the human. To deliver a technology that people actually use, the company must first know what those people need. What time do they go to work? Do they do a school drop on the way? Do they want constant updates on what the car is doing, or to be left alone, or something in between? That’s the sort of information Waymo’s competitors are already collecting en masse.

“While Waymo has a market lead with respect to real world testing of autonomous vehicles on the roads, what they don’t have is the interaction with human behavior that Uber and Lyft do,” says Susan Shaheen, who studies innovation and adoption of new technologies at UC Berkeley’s Transportation Sustainability Research Center.

Uber’s tech may not be as mature as Waymo’s—during WIRED’s test ride in September, the human engineer took control every few minutes—but the company knows a lot about what riders want. On top of its 55 million monthly active riders in nearly 600 cities worldwide, it’s running public self-driving trials in Pittsburgh and Arizona. (Its autonomous Volvo SUVs in San Francisco aren’t picking up paying riders, per California law.)

By launching in Arizona, which encourages self-driving testing and doesn’t require companies report anything about their technology or progress, Waymo moves a big step closer to cracking the human problem. (It’s also a poke at Uber, which tests in the area, to go along with the legal battle between the companies.)

If you live in the Phoenix metropolitan area and want to climb aboard, you can apply to join the Early Rider program online by answering a few questions about your travel habits. Waymo hasn’t clarified how it will select participants, or how many it will enroll, but says it will encourage the chosen few to ride as frequently as possible. If you make the cut, you’ll be able to dial up rides in one of Waymo’s sensor-clad Lexus SUVs or Chrysler minivans. Don’t worry—there will still be a safety driver up front, monitoring the tech and ready to step in as needed.

Hopefully for everyone involved, all those Phoenix trips go smoothly. Waymo’s not just working on its tech, it’s introducing it to the general public. But after nearly a decade of work, the company is ready to make a first impression.