Evaluate driver response to active warning system in level-2 automated vehicles.

As vehicles with automated functions become more prevalent on U.S. roadways, maintaining driver attention while the vehicle is engaged in automation will be an important consideration for safe operation of these vehicles. The objective of this paper is to evaluate how drivers respond and adapt to active safety warning signals in a Level 2 automatic vehicle. Specifically, statistical analysis was conducted to evaluate whether the amount of inattention prompts that drivers received changed over time, possibly indicating a change in the amount of inattention that drivers exhibited. The driving performance data was collected from sixteen participants who drove a Level 2 vehicle in an experimental setting, as part of the study Human Factors Evaluation of Level 2 and Level 3 Driving Concepts. A proprietary driver inattention warning system was installed on the experiment vehicles. The system would send a warning signal if the driver's attention was not on the primary driving task for a pre-specified duration. This study focuses on driver's response when experiencing prompts after two seconds of inattention while operating a Level 2 vehicle in automated mode. The results show that on average, the frequency of prompts the participants received decreased over the course of the experiment from 29.9 in the first ten minutes to 18.1/10 min after 110 min. The decrease levelled off after about two hours. The fact that participants received fewer prompts over time suggests that they had fewer instances of inattention lasting at least two seconds as the experiment progressed. This suggests that drivers would adapt to the alert and adjust their behavior to avoid triggering the inattention alert. The results of this study provide evidence for a potential benefit of incorporating a prompting system in vehicles with automated functions.