SAN FRANCISCO -- California regulators, calling for caution on self-driving cars, today proposed rules that would sharply restrict their use on the state’s roads -- and place an outright ban on “driverless” cars that travel with no humans onboard.

Under the proposal by the California Department of Motor Vehicles, all autonomous cars would need a steering wheel and pedals when operating on California’s public roads. Behind the controls, they would need a licensed driver with an “autonomous vehicle operator certificate” capable of taking control if something goes awry.

In a statement today, DMV Director Jean Shiomoto said the agency’s main concern is “the safety of autonomous vehicles and the safety of the public who will share the road with these vehicles.”

Google impact

The rules, if finalized, could prompt technology companies such as Google, and automakers such as Mercedes-Benz and Tesla, to look beyond California for their first deployment of self-driving cars. This summer, Google started testing its self-driving cars in Austin, Texas, where a culture of business-friendly regulation could make it easier to introduce the technology to the public.

In a statement today, Google decried the proposal, saying California’s rules would hold back a technology with the potential to prevent car crashes and improve the mobility of people who currently cannot drive.

“Safety is our highest priority and primary motivator as we do this,” spokesman Johnny Luu wrote in an e-mail. ”We’re gravely disappointed that California is already writing a ceiling on the potential for fully self-driving cars to help all of us who live here.”

Today’s proposal stems from a law, passed in 2012 by California legislators, ordering the state’s Department of Motor Vehicles to issue rules for the testing and use of autonomous vehicles. The DMV already has completed testing rules that require experimental vehicles to be operated by trained test drivers and to have a steering wheel when operated on public roads.

The newest rules would effectively block the commercial deployment of “driverless” cars, which could function as robotic taxis that pick up passengers and drop them off at the destination of their choosing. Established car companies also are dreaming of such a capability, which could enable personal cars that drive themselves to faraway parking spaces as if guided by robotic valets.

“Given the potential risks associated with deployment of such a new technology, [the] DMV believes that manufacturers need to obtain more experience in testing driverless vehicles on public roads prior to making this technology available to the general public,” the agency said today.

Under the proposal, autonomous cars would also need to meet new safety and performance requirements, with testing and certification by a third-party auditor. To get a three-year operating permit, manufacturers would need to submit regular reports on the safety and usage of their self-driving cars.

As of Dec. 3, the companies certified to test autonomous cars on California roads were automakers BMW, Ford, Honda, Mercedes-Benz, Nissan, Tesla and Volkswagen Group; suppliers Bosch and Delphi; and Silicon Valley technology companies Google and Cruise Automation.

Safety debate

Developers of self-driving cars have generally warned the DMV that strict rules could slow the rollout of a nascent technology, while some consumer groups have called for regulation to ensure that self-driving cars are safe.

The agency has “admirably served as traffic cop,” John Simpson, director of the privacy project at Consumer Watchdog, said in a statement, calling today’s proposal a set of “reasonable limits to protect public safety.”

The DMV has scheduled meetings to solicit public comments on Jan. 28 in Sacramento and Feb. 2 in Los Angeles.