Driver mistakes play a role in virtually all crashes. That’s why automation has been held up as a potential game changer for safety. But autonomous vehicles (AVs) might prevent only around a third of all crashes if automated systems drive too much like people. 1/8 
According to a national survey of crashes, driver error is the final failure in the chain of events leading to more than 9 out of 10 crashes. A new analysis suggests that only about a third of those crashes were the result of mistakes that AVs would be expected to avoid. 2/8
IIHS researchers examined more than 5,000 police-reported crashes. Collected by the National Highway Traffic Safety Administration, this sample is representative of crashes across the United States. 3/8
Researchers reviewed the case files and separated the driver-related factors that contributed to the crashes into five categories. 4/8
Crashes due to only sensing and perceiving errors accounted for 24% of the total, and incapacitation accounted for 10%. Researchers assumed AVs would prevent those crashes that were caused exclusively by perception errors or involved an incapacitated driver. 5/8
The remaining two-thirds might still occur unless autonomous vehicles are also specifically programmed to avoid other types of predicting, decision-making and performance errors. 6/8
Planning and deciding errors, such as speeding, were contributing factors in about 40% of crashes in the sample. The fact that deliberate decisions made by drivers can lead to crashes indicates that rider preferences might sometimes conflict with the safety priorities of AVs. 7/8
“Our analysis shows that it will be crucial for designers to prioritize safety over rider preferences if autonomous vehicles are to live up to their promise to be safer than human drivers,” says IIHS Research Scientist Alexandra Mueller. Full report: go.iihs.org/news-AV-crashes 8/8
