Uber self-driving test vehicle fatally strikes pedestrian in Tempe

What happened

At 9:58 p.m. on March 18, 2018, a modified 2017 Volvo XC90 operated by Uber’s Advanced Technologies Group was traveling north on N. Mill Avenue in Tempe, Arizona. The vehicle had been in autonomous mode for about 19 minutes, with one operator in the driver’s seat. A 49-year-old pedestrian was walking a bicycle across the northbound lanes at a location without a crosswalk.

According to the NTSB, the vehicle was traveling 45 mph as it approached. The automated driving system detected the pedestrian 5.6 seconds before impact and continued to track her, but it never accurately classified her as a pedestrian or predicted her path. By the time the system determined a collision was imminent, the situation was beyond the response specifications of its braking system, and the design relied on the human operator to intervene.

Video from the vehicle showed the operator looking toward a cell phone for an extended period. She looked back at the road about one second before impact and began steering left 0.02 seconds before the vehicle struck the pedestrian at 39 mph. The pedestrian died. The operator was not injured.

The system involved

The vehicle was a 2017 Volvo XC90 SUV fitted with Uber’s proprietary developmental automated driving system and operated as a test vehicle on public roads with a single human operator. The NTSB’s preliminary report, as described by the Associated Press, said emergency braking maneuvers were not enabled while the vehicle was under computer control, in order to reduce erratic vehicle behavior, and that the system was not designed to alert the operator. Volvo’s factory automatic emergency braking was also disabled while the vehicle was in autonomous mode.

Investigation and response

The NTSB investigated the crash (HWY18MH010) and issued report HAR-19-03. It determined the probable cause was the vehicle operator’s failure to monitor the driving environment and the operation of the automated driving system because she was visually distracted by her personal cell phone throughout the trip. Contributing factors were Uber ATG’s inadequate safety risk assessment procedures, ineffective oversight of operators and lack of mechanisms to address automation complacency, all tied to an inadequate safety culture; the pedestrian’s impaired crossing outside a crosswalk; and the Arizona Department of Transportation’s insufficient oversight of automated vehicle testing. The board issued six recommendations to NHTSA, the state of Arizona, the American Association of Motor Vehicle Administrators and Uber ATG.

Uber suspended testing in Arizona, Pittsburgh, San Francisco and Toronto after the crash and, by May 2018, had withdrawn its self-driving cars from Arizona, the Associated Press reported. Uber said it was conducting an internal safety review.

The backup driver was charged with negligent homicide. In July 2023 she pleaded guilty to endangerment and was sentenced to three years of probation, KJZZ reported.

What is not established

The Associated Press, describing the NTSB’s preliminary report, said the system detected the pedestrian about six seconds before impact at 43 mph; the NTSB’s final investigation page gives 5.6 seconds and a recorded approach speed of 45 mph. The final figures are used here.