Google self-driving cars have been involved in 11 collisions over the six years and the 1.7 million miles the company has been testing the vehicles.
All of the accidents were minor, caused no injuries and resulted when a human driver was behind the wheel, Chris Urmson, director of Google's self-driving car program wrote in a blog post on Medium. "Not once was the self-driving car the cause of the accident," Urmson said.
Earlier, the Associated Press had reported that Google's autonomous cars had been involved in at least three fender benders in California since last September when a new state law went into effect requiring all organizations testing autonomous vehicles on California public roads to report accidents.
Google is one of several companies testing self-driving vehicles in California. Others include Delphi, Tesla, Audi, Daimler Benz and Nissan. The companies are working on developing cars that will one day be capable of operating on public roads in an autonomous fashion with very little to no human involvement.
The goal is to improve vehicle safety with technologies that help remove blind spots, detect objects at greater distances and respond to dangerous situations much faster than human drivers. Google has claimed that its autonomous vehicles are capable of detecting objects two football fields away in all directions.
Google's testing has mostly involved Lexus SUVs equipped with autonomous vehicle technology and basic controls for a human driver in situations where the technology is unable to complete an operation safely for any reason, AP said in its report.
According to Urmson, Google currently has a fleet of 20+ self-driving cars and a team of drivers testing the vehicles. The cars have self-driven over 1 million miles of the 1.7 million miles in testing that Google has performed so far.
Google last September also released a prototype of a fully functional all-electric, self-driving car that is slated for public tests in California later this year. Google plans to build about 100 of the two-seat vehicles, none of which will has a steering wheel, accelerator or brake pedal. During the test phase at least, Google's prototype vehicle will have a maximum speed of 25 miles per hour. The company hopes to be able to get permits to test these cars in California this year.
In his blog post, Urmson wrote that one of the keys to understanding the safety capabilities of autonomous vehicles is to have a "baseline" of accident activity on typical suburban streets. Because many accidents do not make it to official statistics, it is important to get a sense for how often collisions happen as the result of other drivers,
"Even when our software and sensors can detect a sticky situation and take action earlier and faster than an alert human driver, sometimes we won't be able to overcome the realities of speed and distance," Urmson noted. "Sometimes, we'll get hit just waiting for a light to change."
In fact, seven of Google's 11 collisions resulted from people hitting its autonomous cars from behind, mainly at traffic lights. Google's vehicles have also been side-swiped a couple of times and hit once by a car rolling through a stop sign, Urmson wrote. Not surprisingly, most of the minor collisions that Google reported happened on city streets.
Prior to its tests in California, Google conducted similar tests in Nevada as well. In May 2012, it became the first company in the United States to be issued a license for autonomous vehicle testing by a state department of motor vehicles.