In California testing of autonomous vehicles, Waymo recorded the fewest number of...

In California testing of autonomous vehicles, Waymo recorded the fewest number of disengagements, when the vehicle handed off control to the human operator.

Photo courtesy of Waymo/FCA.

In its newly released series of 2018 disengagement reports, the California Department of Motor Vehicles found that Waymo had the fewest autonomous vehicle disengagements per mile last year and Apple had the most, reports Roadshow by CNET.

Disengagements are incidents where the AV relinquishes control back to the human test operator. The series of 2018 disengagement reports cover all companies that received a permit to test AVs. 

As one of the leaders in self-driving vehicle development, it's not unexpected that Waymo had the least amount of disengagements — an average of 0.09 per 1,000 miles driven. Based on the 1.26 million miles its AVs covered in 2018, this translates into more than 11,000 miles driven per disengagement incident, notes CNET.

Conversely, Apple who is a relatively new player in the AV field, fared worst of all AV developers with a whopping average of 871.65 disengagements per 1,000 miles driven. When factoring in the amount of mileage Apple's vehicles covered in 2018, this amounts to an average of just 1.1 miles between disengagement events, notes the report.

Companies vary on how descriptive they are when it comes to explaining the reasons for disengagement events in their reports.

Waymo's report attributes numerous disengagement events to "unwanted maneuver of the vehicle that was undesirable under the circumstances." It also had some that were caused by object-detection problems and a handful linked to recklessly behaving road users. Apple's report uses more vague language, attributing disengagement events to reasons like "manual takeover" and "controls."