Data Tracker

California’s self-driving cars are rolling – and sometimes crashing

Self-driving cars have logged hundreds of thousands of test-drive miles on California highways over the last few years and could be available for public use by the end of 2017.

Manufacturers, though, are still working out the kinks. Sometimes the vehicles crash. Other times, self-driving systems disengage, which means the vehicle shifts into manual mode – triggered either by the driver or vehicle sensors. Under state law, the Department of Motor Vehicles is keeping track of all of it.

The DMV filings do not offer conclusive evidence about which vehicles are the safest, and the reports show that accidents and disengagements represent a tiny fraction of vehicles’ time on the road.

But DMV spokeswoman Jessica Gonzalez said the department uses the disengagement reports to track how a company’s technology has evolved over time. It also reviews the accident reports – not to assign fault but to gain insight into how “conventional vehicles with a driver are interacting with autonomous vehicles on California roadways,” she said.

California has permitted 30 manufacturers to test-drive autonomous vehicles, including Tesla Motors, BMW and Google. Twenty-one manufacturers currently are testing self-driving vehicles with a test driver behind the wheel, according to the DMV.

Manufacturers had filed 30 accident reports with the state between late 2014 and mid-April, records show. In most of the crashes, a conventional vehicle had rear-ended an autonomous test vehicle at a traffic light or while the autonomous vehicle waited to turn.

One accident report suggests that the crash might have been prevented if the driver had stayed in autonomous mode instead of disengaging. The Google autonomous vehicle hit the brakes as it neared a Mountain View intersection because its sensors detected that another vehicle would run a red light. The driver turned off autonomous mode and “immediately thereafter, the other vehicle ran through the red light and collided with the right side” of the Google vehicle at 30 mph, according to the company’s filing.

Reports from Google and several other companies through 2015, meanwhile, showed hundreds of disengagements. Only a small number of those might have prevented crashes, companies say. Mercedes-Benz, for example, listed “driver was uncomfortable” as the explanation for dozens of disengagements.

“Our objective is not to minimize disengagements,” Google LLC wrote the DMV in December 2015. “Rather, it is to gather, while operating safely, as much data as possible to enable us to improve our self-driving system.”

California lawmakers set the state on the road to self-driving cars when they overwhelmingly approved Senate Bill 1298 in 2012. Autonomous vehicles, supporters say, will reduce human-caused deaths on the roadways, increase mobility for elderly and disabled people, and improve access to public transit.

Under DMV rules that took effect in 2014, manufacturers could start testing autonomous vehicles with a driver present.

New proposed DMV regulations would allow manufacturers to also test driverless vehicles. In addition, the proposed regulations would allow the public to use self-driving cars on public roads.

The department took feedback on the proposed rules last month. Final regulations are on track to be approved by August and take effect in November.

Data Tracker is a regular feature that breaks down the numbers behind today’s news. Explore more trends at