Waymo, formerly known as Google’s self-driving car, is launching a fully autonomous Uber-like ride-hailing service with no human driver behind the wheel, after testing the vehicles on public roads in Arizona.

Waymo, which is owned by Google parent Alphabet, said members of the public will begin riding in its fleet of modified Fiat Chrysler Pacifica minivans outfitted with self-driving technology in the next few months. Passengers will initially be accompanied in the back seat by a Waymo employee, but will eventually travel alone in the robotic car.

The service will first be available to those who are already part of the company’s public trial already under way in Phoenix. Rides will be free to start with, but Waymo expects to begin charging for journeys at some point.

“Because we see so much potential in shared mobility, the first way people will get to experience Waymo’s fully self-driving technology will be as a driverless service,” said Waymo’s chief executive John Krafcik as he announced the new service at the Web Summit technology conference in Lisbon.

“To have a vehicle on public roads without a person at the wheel, we’ve built some unique safety features into this minivan. Our system runs thousands of checks on itself every second. With these checks, our systems can instantly diagnose any problems and pull over or come to a safe stop if needed,” said Krafcik.

The service marks a major step forward in the development and roll-out of fully autonomous vehicles. While self-driving car companies have routinely tested their vehicles on public roads, they usually have a human sitting behind the wheel ready to take over should the autonomous technology fail.

Waymo has been testing the automated Chrysler Pacifica minivans without a human backup since 19 October in the Phoenix suburb of Chandler, Arizona, which has no restrictions on self-driving cars. The trials and new service have given Waymo the march on competitors Uber and other tech and automotive manufacturers such as Delphi, General Motors, Intel, Uber, Lyft, Apple and Tesla.

Autonomous vehicles are seen as the logical next step for ride-hailing firms such as Uber, and perceived as an existential threat by the firm, which began ploughing money into its own self-driving efforts.

Waymo is a pioneer of self-driving technology and has tested its system in six states across the US, the latest being Michigan. It has more than eight years of testing under its belt, after beginning as Google’s self-driving car research project under its moonshot division, X.

In January, Krafcik unveiled a suite of self-driving hardware developed in-house, including an enhanced vision system, improved radar and laser-based lidar – technology that has seen lawsuits with Uber over intellectual property and the involvement of former Google engineer Anthony Levandowski.

Krafcik said Waymo was exploring many applications for its technology, including ride-sharing, personal use vehicles, transportation, trucking and logistics.

In April, driving statistics compiled by analyst firm Edison Investment Research found that Waymo’s self driving technology was 5,000 times better than Uber’s, which was ranked the worst of six major self-driving car companies testing its vehicles. Edison’s data showed that Uber’s self-driving cars forced a human to take over once every mile driven. By contrast, Waymo’s technology faced a similar situation once every 5,128 miles driven, with more than half a million miles driven in the last 12 months, something that must have been ironed out in the last six months for driver-free operations to be allowed.

Self-driving vehicle firms say the robot cars have the potential to be safer than human-driven vehicles because there is no risk of drowsiness, distraction or drunkenness. Autonomous vehicles also have the potential to restore life to those areas and industries that have suffered from stricter drink-drive laws, such as country pubs and sports clubs, and may help reduce congestion and pollution in urban areas by taking private cars off the road.