Waymo driverless cars crash 68% less than human drivers, IIHS study finds
New IIHS research finds Waymo's driverless vehicles crashed 68% less often per mile than human drivers in four cities, while warning the federal safety-data system needs improvement.
- 68%
- 50 million
- 222 billion
- 22%
What Happened
A new IIHS study finds Waymo's driverless vehicles deployed in San Francisco, Phoenix, Los Angeles and Austin were involved in 68% fewer crashes per vehicle mile traveled than human drivers, when restricted to crashes a person would typically report to police. Waymo vehicles traveled about 50 million driverless miles during the 2021–2024 study period, compared with about 222 billion miles by human drivers in the same places. Waymo was involved in 85% fewer single-vehicle crashes and 81% fewer injury crashes per mile than human drivers.
Started as Google's self-driving car project.
Launched its driverless robotaxi service for the public in Phoenix.
Expanded driverless service to San Francisco.
Expanded to Los Angeles.
Began limited operation in Austin.
Waymo's vehicles are classified as Level 4 on the SAE International automation scale, meaning they can drive without human supervision under certain conditions. By contrast, widely available Level 2 systems like General Motors' SuperCruise and Ford's BlueCruise require an alert human ready to take over, and monitoring them can cause attention fatigue or overtrust. Level 3 systems are rare and need a human in the driver seat ready to intervene when asked, and Level 5 vehicles that drive under all conditions do not yet exist.
The federal Standing General Order, which began requiring self-driving companies to report crashes in 2021, is the only national database for such incidents, but companies don't have to report miles driven. California has required crash reporting since 2014, and an SGO amendment in 2025 aligned damage thresholds with state rules, under which people usually report crashes causing injury or more than $1,000 in property damage. However, about half of all crashes and a third of injury crashes go unreported, while companies are more likely to report qualifying crashes because of compliance risks and costly sensors. IIHS researchers cleaned 2021–2024 reports from Waymo, Cruise, Zoox and others, eliminating about a quarter of records that were redundant, off public roads or not real crashes. They judged which remaining incidents a person would report; only 22% of 736 automation-engaged crashes were likely police-reportable — 89 involving Waymo, 50 Cruise, 10 Zoox and 10 other companies, with 64 of Waymo's 89 in driverless operation.
- Phoenix: 76% lower
- San Francisco: 35% lower
- Los Angeles: 71% lower
- Austin: 4% higher (small sample)
“The results show that, on a limited scale, these driverless cars are safer than human drivers — who can be impaired or drowsy or suffer lapses in attention. However, the present data collection system isn't good enough to allow continuous monitoring of a large-scale expansion.”
“Those are encouraging signs for the future of driverless vehicles. Now we need to get the data collection system right, so that we can ensure that level of safety continues as these technologies become more prevalent.”
Why this matters
A rigorous IIHS comparison shows Waymo's driverless vehicles crashed substantially less often than human drivers per mile in four cities, offering evidence the technology can improve safety. But the study also warns federal crash reporting lacks the mileage and reporting-consistency data needed to monitor a large-scale rollout or compare other companies, which matters for regulators, riders and automakers.
Terms in This Story
- Level 4
- A vehicle that can perform all driving tasks without human supervision under certain conditions.
- VMT
- Vehicle miles traveled, a measure of how much vehicles are driven.
- Standing General Order
- A NHTSA rule requiring companies to report crashes involving automated driving systems.
- Robotaxi
- A self-driving taxi that operates without a human driver.
Summarised from the linked release; details can be imperfect — always verify against the original source.