One of the company's Lexus vehicles was driving autonomously towards an intersection in Mountain View, Calif., outside Google's corporate headquarters.
The light was green, but traffic was backed up on the far side, so three cars -- including the Google Lexus -- braked and came to a stop so as not to get stuck in the middle of the intersection.
"After we'd stopped, a car slammed into the back of us at 17 mph -- and it hadn't braked at all. The clear theme is human error and inattention," Urmson wrote. "We'll take all this as a signal that we're starting to compare favorably with human drivers."
Urmson noted that none of the accidents in which people hit a self-driving vehicle resulted in a police report , even the July 1 crash, although the police were on-site. What's not that clear is why Google waited more than 15 days to report on the accident, even though most of the evidence shows that the accident was the fault of another driver.
"Our braking was normal and natural, and the vehicle behind us had plenty of stopping distance -- but it never decelerated," Urmson explained. "This certainly seems like the driver was distracted and not watching the road ahead. Thankfully, everyone in both vehicles was okay, except for a bit of minor whiplash, and a few scrapes on our bumper. The other vehicle wasn't so lucky; its entire front bumper fell off."
This is not the first time Urmson has reported on the company's safety record when it comes to self-driving vehicles. In May, he wrote a blog post revealing that Google's self-driving cars had been involved in 11 minor accidents during the past six years.
However, Ursom was careful to point out that none of the accidents were the fault of the self-driving car, but rather of distracted drivers around the vehicle.
Despite the occasional fender-bender, Google shows no signs of slowing down when it comes to developing the program.
Earlier this month the company announced with a blog post that it has chosen Austin, Texas, as a new testing location for its self-driving car project.
One of the company's Lexus SUVs is there now, safety drivers aboard, driving a few square miles north and northeast of downtown Austin.
Google's fleet of more than 20 self-driving vehicles and its team of safety drivers have driven 1.7 million miles -- both manually and autonomously. The cars have self-driven nearly a million of those miles. They now complete an average of around 10,000 self-driven miles a week.
Nathan Eddy is a freelance writer for InformationWeek. He has written for Popular Mechanics, Sales & Marketing Management Magazine, FierceMarkets, and CRN, among others. In 2012 he made his first documentary film, The Absent Column. He currently lives in Berlin. View Full Bio
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