WASHINGTON • Software detected the woman almost six seconds before Uber's self-driving car hit her, investigators say, in the crash that would lead to her death and prompt the ride-share giant to slam the brakes on its autonomous vehicle testing.
But the sport utility vehicle did not try to stop until about a second before impact. One big reason: It was not designed to recognise a pedestrian outside a crosswalk, according to documents released this week by the National Transportation Safety Board (NTSB) after a 20-month investigation.
Revelations that Uber failed to account for jaywalkers - with deadly results in Tempe, Arizona, in March last year - fuel longstanding objections from critics who accuse companies like Uber of rushing to deploy vehicles not ready for public streets.
They are sceptical that automakers eager to lead on industry-transforming technology are doing enough to avoid another tragedy as they continue to test cars out in the real world.
"Even the most junior human driver knows to expect that people sometimes walk outside of crosswalks," said Mr Jason Levine, executive director of the Center for Auto Safety, a District of Columbia-based nonprofit.
"When we have public road testing that has programming that essentially chooses to ignore the realities of how people interact with public infrastructure, it's really dangerous."
The bigger question for Mr Levine: Could similar serious oversights plague other models across the self-driving industry? "The answer is, we don't know, because there's no requirements around how you programme this technology before you put it on the road," he said. He wants to see federal regulation.
Uber has made "critical programme improvements" in the wake of Ms Elaine Herzberg's death, spokesman Sarah Abboud said in a statement. The company's system is now able to handle scenarios like jaywalking in which people or cyclists are not following road rules, she added, though human drivers may still need to intervene at times.
She declined to say how long Uber had been aware of the failure to recognise a pedestrian not in a crosswalk and said the company is not commenting on specifics of the investigation because it is ongoing.
The crash that spurred the inquiry is thought to be the first death related to the testing of autonomous vehicles. A human was in the driver's seat but did not manage to stop the car from ploughing into 49-year-old Herzberg near a busy intersection, according to the authorities.
Hit as she was crossing the street, Ms Herzberg died in hospital. Multiple issues contributed to the crash, the NTSB's documents indicate. She would likely be alive if Uber had not blocked its car from using a built-in automatic emergency brake, the board found, though it will not issue its decision on what caused the death until its meeting later this month.
But another major problem was the software's inability to identify a person in the car's sights and its resulting failure to predict how that person would move into the vehicle's path.
Uber's system perceived Ms Herzberg as a vehicle, a bicycle and an "other" object in the seconds before collision - but not a human being.
The death halted Uber's testing as scores of companies, from Google to General Motors, explored self-driving technology. It drew strong reactions from many experts who warned of a need to hold vehicles deployed in public to stricter standards.
But others argued that cars cannot be fine-tuned without real-world driving experience. Nine months later, Uber resumed its test drives in Pittsburgh. The company hopes to bring its self-driving cars back to other cities such as San Francisco, Ms Abboud said on Wednesday, but is focusing right now on using human drivers to collect data on those particular locations that it can incorporate into its testing in controlled environments.
Arizona was particularly hospitable to companies looking to test their young autonomous tech in the years leading up to Ms Herzberg's death.
Before that crash, Governor Doug Ducey, a Republican, said he welcomed Uber's self-driving cars "with open arms and wide open roads" while criticising California for stifling such testing with "more bureaucracy and more regulation".
Difficulties recognising pedestrians are not unique to Uber's self-driving cars, said Mr Jamie Court, who as president of the group Consumer Watchdog has been critical of companies' willingness to deploy the technology.
Across the board, he said, many autonomous vehicles struggle to successfully navigate more than 16 or 32km without human intervention, though some standouts like Google's car can make it much farther.
But the NTSB's findings on Uber's tech is especially alarming, he said. "Robot cars would do well driving in a world of robots, but not on roads and crosswalks where human beings have the right of way," Mr Court said.