Towards a Practical Methodology for Defining Competent Driving

Automated vehicles (AVs) will play an important role in future mobility systems, which promise a drastic reduction in traffic casualties, better road utilization and personalized mobility. One of the main challenges to realize this future is to ensure that the presence of AVs in mixed traffic has a net positive effect on traffic safety. We posit that this would only be the case if their driving behavior and skills were indistinguishable from those of competent drivers, that is, if they show good roadmanship. This article introduces a novel, practical methodology to operationalize the concept of roadmanship in such a way that it reflects the customs of a local driver population. It is based on mathematical formulas, called assertions, that describe the relationship among traffic participants and/or elements of driving behavior. At any given time, a driver should maintain the value of applicable relationships within “acceptable” ranges for his/her driving to be deemed competent. “Acceptability” is a subjective construct that is defined by expert opinion. To address this, the methodology includes a novel type of driving study that allows expert driver assessors to record their opinions about the quality of driving during driving sessions, link them to vehicle and traffic kinematics, and extract acceptable ranges for the assertions. The resulting set of assertions can then be used to assess whether a driver, human or otherwise, is competent.