The AV braked in response to the bus pulling out but did so too late. It rear-ended the bus at 10 mph. The apparent cause of the collision was an issue with how the AV interpreted the movement of the articulated bus that was involved in the collision. According to Cruise, the AV made an incorrect prediction about the position of the bus based on the front section of the bus which it could no longer see. Because of this, it couldn’t “see” the rear section of the bus.

In response to this, Cruise worked on a software update that helped to recognize articulated vehicles. Within two days of the collision, the update was validated and pushed out to the Cruise fleet. Now, Cruise filed its voluntary recall to make sure the previous version of its software is replaced with the updated software.