On March 18, at 9:58 p.m., a self-driving Uber car killed Elaine Herzberg. The vehicle was driving itself down an uncomplicated road in suburban Tempe, Arizona, when it hit her. Herzberg, who was walking across the mostly empty street, was the first pedestrian killed by an autonomous vehicle.
The preliminary National Transportation Safety Board report on the incident, released on Thursday, shows that Herzberg died because of a cascading series of errors, human and machine, which present a damning portrait of Uber’s self-driving testing practices at the time.
Perhaps the worst part of the report is that Uber’s system functioned as designed. There were no software glitches or sensor malfunctions. It just didn’t work very well.
According to the report, the object-detection system misclassified Herzberg when its sensors first detected her “as an unknown object, as a vehicle, and then as a bicycle with varying expectations of future travel path.” That led the planning software to make poor predictions for her speed and direction, as well as its own speed and direction.
1.3 seconds before the impact, the self-driving computer realized that it needed to make an emergency-braking maneuver to avoid a collision. But it did not. Why? Uber’s software prevented its system from hitting the brakes if that action was expected to cause a deceleration of faster than 6.5 meters per second. That is to say, in an emergency, the computer could not brake.