Safer than the average human driver (who is less safe than me)? Examining a popular safety benchmark for self-driving cars

Although the level of safety required before drivers will accept self-driving cars is not clear, the criterion of being safer than a human driver has become pervasive in the discourse on vehicle automation. This criterion actually means “safer than the average human driver,” because it is necessarily defined with respect to population-level data. At the level of individual risk assessment, a body of research has shown that most drivers perceive themselves to be safer than the average driver (the better-than-average effect). Method: Using an online sample, this study examined U.S. drivers’ ratings of their own ability to drive safely and their desired level of safety for self-driving vehicles. Results: This study replicated the better-than average effect and showed that most drivers stated a desire for self-driving cars that are safer than their own perceived ability to drive safely before they would: (1) feel reasonably safe riding in a self-driving vehicle; (2) buy a self-driving vehicle, all other things (cost, etc.) being equal; and (3) allow self-driving vehicles on public roads. Conclusions: Since most drivers believe they are better than average drivers, the benchmark of achieving automation that is safer than a human driver (on average) may not represent acceptably safe performance of self-driving cars for most drivers. Practical applications: If perceived level of safety is an important contributor to acceptance of self-driving vehicles, the popular “safer than a human driver” benchmark may not be adequate for widespread acceptance.