If autonomous vehicles want to go mainstream, they need to go as far as they can to ensure the safety of everyone on the road. And no one needs more protection than so-called vulnerable road users, such as pedestrians, cyclists and motorcyclists, thousands of whom die every year.
Waymo, the Alphabet-owned robotaxi company, recently published a new study examines hundreds of these types of accidents involving vulnerable road users, what it calls “the largest data set of its kind in the US.”
Approximately 40,000 people in the United States die each year in car accidents. But while automakers have become very good at protecting people inside vehicles, they have essentially neglected the safety of people outside them.
Meanwhile, the academic community has shown little interest in studying vulnerable road user (VRU) injuries, so Waymo set out to rectify that, said John Scanlon, Waymo safety researcher. The goal was to shed light on this under-examined area of traffic research in the hope that the results could help make Waymo's driverless technology safer, and maybe even help some of its rivals as well.
The academic community has shown little interest in studying injuries to vulnerable road users.
The new research comes amid a deadly period for pedestrians and cyclists in the US, where reports of injuries and deaths remain frustratingly high. In 2022, 7,522 pedestrians were killed in car accidents and more than 67,000 pedestrians were injured nationwide, according to the National Highway Traffic Safety Administration.
“An accurate and thorough understanding of the unique safety risks presented to these groups is critical to developing effective strategies to reduce injuries and fatalities,” Scanlon said.
To study these types of injuries, Scanlon and his team first needed footage from hundreds of car accidents, so they partnered with dash cam company Nexar. Examining anonymized Nexar data on 500 million miles of driving, Scanlon's team successfully reconstructed 335 crashes involving VRUs (pedestrians, cyclists, and motorcyclists) in six American cities. However, the data was heavily skewed toward New York City, where 80 percent of the incidents occurred. Anonymous people in the data set suffered moderate to severe injuries, depending on the collision, but none of the accidents Waymo studied were fatal.
The result is the “largest documented naturalistic driving data set in the US,” the company claims. By studying this data, Waymo hopes to gain a better understanding of how, when and why vehicle drivers injure vulnerable road users. And by focusing on the “frequency and severity” of crashes, Waymo was able to draw several relevant conclusions from the data set.
At first glance, the results seem pretty obvious. Pedestrians and cyclists were more likely to be injured when they “surprised” drivers, such as trying to cross the street against a traffic light. Additionally, “geometric occlusions,” such as trees, bushes, buildings, or other vehicles, created a higher risk of injury. And the vehicle's trajectory, the direction in which it travels or turns, played an important role.
“It is essential to have an accurate and deep understanding of the unique security risks presented to these groups”
Waymo partnered with VUFO, a Germany-based traffic research group, to develop models for injury risk assessment. It also leveraged anonymized data from the German Accident In-Depth Study, which includes information on thousands of VRU accidents over more than two decades and represents “the most relevant data available in the world today” to estimate injury risk for VRUs.
Waymo's driverless vehicles operate in San Francisco, Los Angeles and Phoenix, making more than 150,000 paid trips a week. The company also plans to launch its robotaxi service in Austin and Atlanta. And every day, a self-driving Waymo vehicle must navigate an environment full of vulnerable road users. One wrong move could be deadly, and if the past is prologue, AV operators must be prepared to accept full responsibility for what went wrong.
There have been several collisions with driverless vehicles and some injuries. A cyclist was injured by a Waymo vehicle in San Francisco in February 2024 after leaving behind a truck that was blocking his view. And last year, a Cruise vehicle hit a pedestrian and then dragged her to the side of the road. The company is still dealing with the fallout.
Scanlon said that by better understanding these types of collisions, AV operators can recreate them in both simulation and real-world testing, which could lead to safer decisions.
“This analysis can serve as a starting point to identify the baseline driving risk associated with VRU crashes in dense urban areas, which will, in turn, enable testing and performance evaluation of autonomous vehicles,” he said.
