Advancing Vision Zero: Waymo’s Research on Speed and Seatbelt Safety Impact

At Waymo, our goal is to make streets safer for everyone – and our strong safety record reflects that commitment. From 360-degree perception to advanced collision avoidance, many factors contribute to how we help reduce crashes on public roads. But some of the most impactful safety measures are also the simplest – such as consistently obeying speed limits, ensuring seatbelt use, and driving the safest vehicles. Today, we're sharing two new research papers that demonstrate how these fundamental practices can help move us closer to the Vision Zero goal of eliminating traffic fatalities and severe injuries.

"This research offers new evidence of how we can benefit from life-saving safety practices to advance Vision Zero," said Leah Shahum, Founder and Director, Vision Zero Network. "By demonstrating real-world outcomes, Waymo’s work highlights how public and private sectors can collaborate to accelerate meaningful progress towards safe roads for all."

The Safety Impact of Speed Limit Compliance

Speeding is one of the leading causes of traffic deaths and severe injuries. Building on our previous research, our new study analyzes aggregated anonymized data from over one million unique speed observations on surface streets in Phoenix and San Francisco to measure speed compliance and estimate the safety benefits of following posted limits.

Across different roadway types in both cities, 33-49% of human drivers were observed to be speeding. By applying an established exponential model that links vehicle speeds to crash outcomes, our researchers estimated that if everyone followed the speed limit, serious injuries could be reduced by 18-30% and fatalities by 27-42%, depending on the type of the road.

When combined with fatality data from NHTSA's Fatality Analysis Reporting System (FARS), these reductions translate to approximately 82 lives saved annually on surface streets in these two cities alone – 75 in Phoenix and 7 in San Francisco.

Enhancing Safety Through Seatbelt Use and by Using the Safest Vehicle Platforms

Our second paper examines how seatbelt use and vehicle age affect injury risk. While the national average for rear seatbelt use is at an all-time high of 82%, studies show that fewer than 40% of ride-hailing passengers buckle up. At the same time, the average age of passenger vehicles in the U.S. is 14 years, meaning that many lack the latest developments in crashworthiness, designed to protect car occupants during a crash.

Using a state-of-the-art occupant injury risk model and data from nearly 15,000 collided human-driven vehicles, our researchers found that increasing rear seatbelt usage from 40% (typical of human-driven ride-hailing) to 82% (the national average) could reduce serious injuries by 41% and critical injuries by 50%.

The research also shows significant safety benefits from newer vehicles. Compared to 2010 model year vehicles, 2020 models were associated with 34% fewer serious injuries and 57% fewer critical injuries,  including fatalities, with additional safety improvements in subsequent model years.

Most significantly, a fleet with 100% seatbelt compliance and the newest vehicle models could reduce serious and critical injuries, both of which can include fatalities, by 75% and 90% respectively, compared to today’s ride-hailing services.

Applying Research to Real-World Transportation

Waymo is already making streets safer in the areas we operate, advancing the goals of Vision Zero. Recognized by the highest FIA Road Safety Index, the Waymo Driver is always alert, respects speed limits, promotes seat belt use, and drives the safest vehicles among many other safety best practices. The research we're sharing today is part of Waymo’s ongoing work to understand and quantify safety factors that benefit all road users, regardless of transportation mode. 

"This research adds to the growing body of scientific evidence regarding the life-saving potential of the Vision Zero principles and helps guide our approach to building the world's most trusted driver," said Trent Victor, Waymo’s Director of Safety Research and Best Practices. "By sharing these findings, we hope to contribute to evidence-based policies to achieve the goal of eliminating serious injuries and fatalities on our roads."

The seatbelt paper has been peer-reviewed and will appear in the conference proceedings of the International Research Council on Biomechanics of Injury (IRCOBI) later this year. The speed study has been submitted for publication in the journal Traffic Injury Prevention, and is currently under peer review. In the meantime, the full papers are available on our website at waymo.com/safety/research.