Alphabet-owned Waymo is putting its autonomous driving expertise to work in trucking, in a new track for the unit formerly known as Google Car.

Tests taking place currently at a private track in California are to be followed up by trying out rigs, with drivers ready to take the wheels, on roads in Arizona later this year, according to Waymo.

"We're taking our eight years of experience in building self-driving hardware and software and conducting a technical exploration into how our technology can integrate into a truck," a Waymo spokesperson told AFP Friday.

The move ramps up Waymo's challenge to on-demand ride service Uber, which has been investing in technology for self-driving cars and trucks as part of its vision for the future of the San Francisco-based company.

Uber this week said that it fired engineer Anthony Levandowski, accused in a trade secrets suit involving files he purportedly purloined from Waymo before leaving to establish a start-up focused on self-driving trucks.

The case stems from a lawsuit filed in February by Waymo claiming former manager Levandowski took a trove of technical data with him when he left to launch a competing venture that went on to become Otto and was later acquired by Uber.

Waymo argued in the lawsuit that a "calculated theft" of its technology netted Otto a buyout of more than $500 million and enabled Uber to revive a stalled self-driving car program.

US-based Tesla is also stepping up efforts in autonomous driving and is set to launch its first semi-truck in September.