By Abhirup Roy

SAN FRANCISCO California Governor Gavin Newsom late on Friday vetoed a bill to prevent heavy-duty driverless trucks from operating in the state, in a relief for companies developing autonomous technology to haul goods across the U.S.

The labor-backed Assembly Bill 316, which requires a trained human driver to be present in autonomous vehicles weighing over 10,001 pounds, was passed by a heavy majority in both houses of the state legislature.

"Considering... the existing regulatory framework that presently and sufficiently governs this particular technology, this bill is not needed at this time," Newsom said in a veto message on Friday.

A veto by the governor can still be overturned if the legislature chooses to vote in favor of the bill with a two-thirds majority in each house. This, however, is rare and has not happened in California since 1979.

While many states, including Texas and Arkansas, have allowed the testing and operation of self-driving trucks, California - home to Alphabet, Apple and some of the most cutting-edge tech startups - bars autonomous trucks weighing more than 10,001 pounds.

But the department of motor vehicles has been working towards developing a regulatory framework to lift that restriction, prompting the suggested bill, industry sources told Reuters.

Developing autonomous technology has proved harder and more expensive than expected, leading to job cuts and even companies shutting shop. Some that are still testing and deploying driverless trucking operations include Aurora, Daimler Truck, Kodiak Robotics and Gatik.

Supporters of the technology say the bill would hamper chances of achieving autonomous hauling of goods, for example, from the bustling seaports in Southern California to locations across the state, and cause future investments in autonomous infrastructure to flow to other states.

But labor unions led by the International Brotherhood of Teamsters have been calling for Governor Newsom to sign the bill, saying autonomous trucks - some of which weigh over 80,000 pounds - were unsafe and would lead to job losses.

Governor Newsom in his veto message said any regulations framed by the department of motor vehicles would be transparent, with inputs from stakeholders and experts to ensure safety.

He directed the labor and workforce development agency to develop recommendations to mitigate any potential impact on jobs from the deployment of such vehicles.

(Reporting by Abhirup Roy in San Francisco; Editing by Jan Harvey)