Google says its self-driving cars would have been involved in 11 crashes, if it hadn't stepped in

LOS ANGELES (AP) -- Google says its futuristic self-driving cars needed some old-fashioned human intervention to avoid 11 crashes during testing on California roads.

The company on Tuesday revealed the results from roughly a year of testing and said they are encouraging, but they show that the technology is still maturing, and has yet to reach its goal of not needing someone behind the wheel.

Google's fleet logs tens of thousands of miles each month, so the 11 instances would be the equivalent of a car having one event every three years, based on how much the average vehicle is driven in the U.S.

There were also 272 cases in which failures of the cars' software or on-board sensors forced the person who must be in the front seat -- just in case -- to grab the wheel.