Google's Chris Urmson explains self-driving car crash - Roadshow

Taking the stage at Austin's SXSW festival, Chris Urmson, director of Google's self-driving car project, explained precisely what happened during a recent collision between a self-driving car and a bus. He talked further about the progress of self-driving car technology and how even that incident was a crucial leaing experience for the technology.

The collision occurred on February 14 between a Lexus RX 450h which Google had modified with sensors and controls to enable self-driving, and a city bus in Mountain View, Califoia. The low-speed collision resulted in minor damage to both bus and car, but no injuries. The collision was the first caused by one of Google's self-driving cars after having covered 1.4 million miles of real world testing.

At SXSW, Urmson explained that the company had taught its cars to move next to the curb when planning a right tu, sidling by traffic stopped at a traffic light, much as human drivers do. As the car proceeded along the curb, it sensed a few sandbags on the road ahead of it, so decided to stop and wait for the lane next to it to clear.

After the light tued green, the traffic began moving. The car detected a city bus coming up the lane, and made the assumption the bus driver would slow down. As Urmson told it, the bus driver assumed the car would stay put, and kept on going. The car pulled out, hitting the side of the bus at about 2 mph.

In the wake of that collision, Urmson said his team "implemented 3,500 new tests to make sure this won't happen again."