California regulators require self-driving car firms to report when humans had to take over from robot drivers for safety, though Google is giving only select data

“Release of the disengagement report was a positive step, but Google should also release any video it has of the disengagement incidents, as well as any technical data it collected.”

In 56 of the 69 driver disengagements reported to the DMV, Google calculated that its car would probably not have come into contact with another object. But, admits Google in its report, “we identified some aspect of the [car]’s behaviour that could be a potential cause of contacts in other environments or situations if not addressed. This includes proper perception of traffic lights, yielding properly to pedestrians and cyclists, and violations of traffic laws.”

Google classified the final 13 disengagements as “simulated contacts”: situations that would have resulted in a crash had the human driver not taken over. “In these cases, we believe a human driver could have taken a reasonable action to avoid the contact but the simulation indicated the [car] would not have taken that action,” the company says.

All self-driving car firms have filed disengagement reports

The report could be seen as a blow to Google’s insistence that self-driving cars should be fully autonomous. It latest prototypes are designed to operate without any driving controls for their human occupants to take over in an emergency (although those currently on public roads do have backup controls fitted).

“It demonstrates that it is valuable to have a safety driver in the vehicle while testing, which is something we’ve always believed,” said Chris Urmson, director of Google’s self-driving car program. “But if you look at [regular] drivers, they’re effectively untrained in America. Expecting them to vigilantly monitor a system that operates as well as this does is a really a very challenging problem."

Google is not the only company to have filed a disengagement report with the DMV. Volkswagen/Audi, Mercedes Benz, Delphi, Tesla, Bosch and Nissan have all filed their reports, which are currently under review by the department to confirm that they contain all the required information. The DMV told the Guardian that it does not currently have an expected date to complete its analysis the data or draw conclusions from it.

While Google has been testing its self-driving cars since 2008, the company will not be releasing disengagement data from before 2014. “This is the period we’re required to share with the DMV. Any data we would have from before that is just outdated,” Urmson says.

Google notes that disengagements have been getting less common over the period of the report. However, Urmson cautions against expecting disengagements to drop regularly, year on year. “We’re continually adding capabilities to our vehicles, pushing them into more challenging situations,” he says. “Over the long view we’d expect disengagements to be improving, but as we test in more challenging weather or driving situations, you could expect locally this to not look as good. And it really isn’t representative of where the technology will be when we’re ready to release it.”

Google’s parent company Alphabet is reported to be planning to spin out its self-driving car technology into its own business later this year.