Emergency Braking Was Disabled Before Fatal Uber AV Crash

The self-driving Uber SUV that killed a pedestrian in Arizona earlier this year had its automatic braking system turned off to prevent erratic driving, the National Transportation Safety Board announced.

In a preliminary report issued May 24, the NTSB drew no conclusions about the cause of the crash but revealed several details that may raise questions about how safe Uber’s testing procedures were. The company has since suspended its self-driving program and is reviewing its safety.

The NTSB’s investigation continues.

The March 18 crash, which claimed the life of Elaine Herzberg, 49, rocked the emerging autonomous vehicle industry and led Uber to suspend all public AV testing in North America. On Wednesday, the company said it is shutting down its Arizona testing operation.

Judging from the NTSB’s preliminary report, the self-driving systems added to the Volvo XC90 may have worked as designed. But because safety features built into the SUV didn’t work when the vehicle was in self-driving mode, it was left up to the safety driver to respond to emergencies.

The Volvo was traveling northbound about 10:00 p.m. local time on Mill Avenue, a multilane road in Tempe, at 43mph, when Herzberg walked her bike into the roadway, the NTSB found. The vehicle’s radar and Lidar sensors detected her about six seconds before impact and identified her as an unknown object, then a vehicle, then a bike and made varying predictions about where she was heading.

Just 1.3 seconds before impact, the self-driving software determined that emergency braking was necessary. But because automatic braking didn’t work when the car was in computer-driven mode, the safety driver had to respond. She engaged the steering wheel right before impact but didn’t brake until just after the crash, the NTSB said.

The way the vehicle was configured, Volvo’s built-in systems for emergency braking — as well as driver alertness detection — would only work when the car was in manual driving mode. And even though the AV system could detect hazards, it had no mechanism for alerting the safety driver. An in-car video released last month shows the driver looking down and away from the road until just before the crash.

The driver later told the NTSB that she was looking at the self-driving interface in the dashboard, which safety drivers used to monitor diagnostic messages and tag events for future review. She said her personal and work phones were in the car but she didn’t use them until she called 911 after the accident.

The NTSB is still reviewing those phones, as well as the vehicle and other information.

Toxicology tests for the pedestrian were positive for methamphetamine and marijuana, the NTSB said. The safety driver, who was not injured, showed no signs of impairment and wasn’t tested.

Uber said Thursday it would let the preliminary report speak for itself.

“Over the course of the last two months, we’ve worked closely with the NTSB. As their investigation continues, we’ve initiated our own safety review of our self-driving vehicles program. We’ve also brought on former NTSB Chair Christopher Hart to advise us on our overall safety culture, and we look forward to sharing more on the changes we’ll make in the coming weeks,” an Uber spokesperson told The Connected Car via email.

The company said Wednesday that it hoped to resume AV testing this summer, starting in Pittsburgh. It plans to do so in a more limited way to test specific use cases and will cooperate with local authorities as well as make safety improvements.

Volvo told The Connected Car on Thursday it has been assisting the NTSB’s investigation and will continue to support it.


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