The Volvo XC90 that hit Elaine Herzberg on a darkened Tempe, Arizona street was travelling 43 mph at the time of impact. Guided by a combination of cameras, radar sensors, and lidar designed to cut through the gloom, the two-ton SUV “saw” the victim 6 seconds before impact, according to a preliminary report released by the National Transportation Safety Board.
The Vovo, operated by Uber Technologies, applied the brakes 1.3 seconds after impact. However, it wasn’t autonomous software that ended up sending pressure the front and rear pistons. A human did that.
It isn’t the NTSB’s job to assign blame in its preliminary report. The agency simply wants to nail down the facts of what occurred in the lead-up to, and aftermath of, the fatal March 18th collision. Here’s some key findings:
Herzberg entered the road 360 feet south of a marked crosswalk, dressed in dark clothing, in an area with no direct illumination. She didn’t turn her face towards the vehicle until the last moment, and the bicycle she was walking across the road had no side reflectors. A toxicology test turned up methamphetamine and marijuana use.
The vehicle blended Volvo’s own collision avoidance system (which includes automatic emergency braking) with Uber’s forward and side-facing cameras, radar, lidar, and navigation sensors. However, “The Volvo functions are disabled only when the test vehicle is operated in computer control mode,” the NTSB noted.
From the NTSB:
The report states data obtained from the self-driving system shows the system first registered radar and LIDAR observations of the pedestrian about six seconds before impact, when the vehicle was traveling 43 mph. As the vehicle and pedestrian paths converged, the self-driving system software classified the pedestrian as an unknown object, as a vehicle, and then as a bicycle with varying expectations of future travel path. At 1.3 seconds before impact, the self-driving system determined that emergency braking was needed to mitigate a collision. According to Uber emergency braking maneuvers are not enabled while the vehicle is under computer control to reduce the potential for erratic vehicle behavior. The vehicle operator is relied on to intervene and take action. The system is not designed to alert the operator.
In the report the NTSB said the self-driving system data showed the vehicle operator engaged the steering wheel less than a second before impact and began braking less than a second after impact. The vehicle operator said in an NTSB interview that she had been monitoring the self-driving interface and that while her personal and business phones were in the vehicle neither were in use until after the crash.
Three sentences here stand out: “According to Uber emergency braking maneuvers are not enabled while the vehicle is under computer control to reduce the potential for erratic vehicle behavior. The vehicle operator is relied on to intervene and take action. The system is not designed to alert the operator.”
We’ve heard reports that Uber was concerned about the high number of “false positives” — objects in the vehicle’s path that needn’t require sudden braking, such as a wind-blown plastic bag. If the vehicle was indeed programmed to initially ignore many objects on the roadway, why wouldn’t there at least be an alert sent to the human driver whose foot is hovering over the brake pedal? A simple rapid beep wouldn’t lead to erratic vehicle behavior, but it would increase safety.
Instead, we have a vehicle operator tasked with avoiding sudden emergencies whose eyes are monitoring a bright multimedia screen, not the darkened road. And no warning to alert the driver to impending danger.
An initial warning could have been sent out six seconds before impact. True, it’s possible the driver wouldn’t have been able to see Herzberg given the factors mentioned earlier, but at least the driver would be looking for something. Brake pressure might even have been applied prior to the vehicle’s conclusion that an emergency maneuver was necessary.
A video released by Tempe police shows the driver staring at the screen for four or five seconds immediately prior to the collision, then looking up and reacting to the sight of Herzberg in the car’s path, presumably less than a second before impact.
In the wake of the crash, Uber shut down on-road testing of its autonomous vehicle fleet, and just yesterday decided to pull out of Arizona altogether. The company has hired a safety official to scrutinize its program.
“We have initiated a top-to-bottom safety review of our self-driving vehicles program, and we have brought on former NTSB Chair Christopher Hart to advise us on our overall safety culture,” Uber said earlier this month. “Our review is looking at everything from the safety of our system to our training processes for vehicle operators, and we hope to have more to say soon.”
[Image: Uber Technologies, via Tempe Police Department]