So far, the "Google car" has enjoyed a seemingly impossible safety record. The company was long able to boast that its self-driving cars had never caused an accident while the software was in control. The only accidents caused by Google's vehicles occurred when humans had taken over.
Unfortunately, that no longer seems to be the case. According to Google, one of its autonomous vehicles recently caused a minor accident during road testing in Mountain View. The car reportedly tried to change lanes, and in doing so, sideswiped a public bus in a very-low-speed collision (just 2 mph). Although the accident was minor, it nonetheless raises concerns about the future of self-driving vehicles.
The accident seems to have been an issue of competing safety priorities. Google said that the vehicle sensed sand bags that had been placed around a storm drain, and changed lanes in response. It is unclear why the vehicle did not detect the bus as it moved over.
Although human drivers have a horrendous safety record, most would have no difficultly interpreting and responding to situations like this. It is unclear if computers can be programmed to make these higher-level judgments (even though they may be more reliable than human drivers most of the time). Google has taken the minor accident as a learning opportunity, saying that it was "a tricky set of circumstances that’s helped us improve an important skill for navigating similar roads."
No one yet knows how self-driving or partially self-driving vehicles will impact road safety overall. In the meantime, incidents like this car accident will provide researchers with valuable information.