California regulators have unveiled revised rules that would allow self-driving cars to travel the state's highways without human drivers for the first time as early as next year, a move that won the support of automakers.
The new rules, unveiled on Wednesday, represent a compromise with automotive and technology companies, which had objected to many of the requirements previously proposed by the state.
The California rules could still conflict with proposed federal legislation that would largely bar states from regulating autonomous vehicles.
But they are a boost for automakers who want to be able to deploy vehicles without human controls in California.
More than 40 companies are testing self-driving vehicles in California with human controls, and most automakers have autonomous research centres in the state, which is the largest US auto market.
The new rules are expected to take effect by June 2018, the state said.
Waymo, the self-driving car unit of Google parent company Alphabet Inc, Ford Motor Co, Tesla Inc, Apple Inc, General Motors Co had sought changes in California.
Previous rules had demanded that firms submit safety assessment reports to state regulators and seek new approval for updated vehicles.
Existing rules also require a backup human driver to be in all driverless vehicles.
Wade Newton, a spokesman for trade group the Alliance of Automobile Manufacturers, said on Wednesday it appeared that California had recognised that “certain onerous” requirements could delay deployment of self-driving technology.
“We appreciate the (state's) attempts to streamline requirements consistent with the recently updated federal guidance,” Newton said.
But the Association of Global Automakers, a trade group representing mostly Asian and European automakers, said California did not go far enough.
“A special permit is still required to deploy, creating regulatory uncertainty and raising concerns about the ability of autonomous vehicles to cross state lines,” it said.
Companies would still need a California permit to test or deploy vehicles on state roads.
California would also require automakers and tech firms to record information about autonomous sensors in the 30 seconds before a collision. Vehicles must follow all state laws “except when necessary for the safety of the vehicle's occupants” or other road users.
Consumer Watchdog criticised the revisions, saying California should stick to its earlier, stricter state requirements.
The group noted local communities could not block testing under the proposal.
Last week, a Senate panel approved a bill aimed at speeding the use of self-driving cars without human controls in the US, a measure that also bars states from imposing regulatory road blocks.
Automakers would be able to win exemptions from safety rules that require human controls if they met certain requirements. States could set rules on registration, licensing, liability, insurance and safety inspections, but not performance standards.
General Motors chief executive Mary Barra told Reuters on Tuesday that the federal legislation “allows us to get this technology on the road,” but declined to say when the automaker might seek approval for exemptions.