The service will initially expand to members of a Waymo early-rider program, who will be able to get rides to or from school, work, shops, pubs or any other local spots they might typically go in their own vehicles.

Waymo on Tuesday said that its self-driving cars are hitting the road without anyone behind the wheel as the Alphabet subsidiary steers toward launching an automated ride service. The subsidiary of Google parent Alphabet has been testing autonomous cars for years, but with a driver behind the wheel to take over if needed.

Waymo chief executive John Krafcik used the Web Summit in Lisbon to announce a portion of its fleet in the Phoenix area will operate in fully autonomous mode with the cars handling all the driving.

"After more than eight years of development, we're taking the next step toward unlocking the potential of fully self-driving technology. Starting now, Waymo's fully self-driving vehicles are test-driving on public roads without anyone in the driver's seat." the Waymo team said in a blog post"

The testing will initially be limited to part of Phoenix, Arizona. Since Waymo began as a project in Google's 'moonshot' lab in 2009, its vehicles have logged more than 3.5 million miles of autonomous driving on US roads, according to the company.

Waymo employees will be the first to test the fully automated rides. The company plans to eventually launch a driverless on-demand ride service, potentially eliminating the need for car ownership in the long term.

"Over the next few months, we'll be inviting members of the public to take trips in our fully self-driving vehicles," Waymo said. "A fully self-driving fleet can offer new and improved forms of sharing: it'll be safer, more accessible, more flexible, and you can use your time and space in the vehicle doing what you want."

The service will initially expand to members of a Waymo early-rider program, who will be able to get rides to or from school, work, shops, pubs or any other local spots they might typically go in their own vehicles. Waymo appears to have a head-start in what is expected to be a competitive race to a ride-sharing future, with established automakers such as Ford and BMW and ride-sharing groups Uber and Lyft in the mix.