The difference in physical and mental fatigue development between novice young adult and experienced middle-aged adult drivers during simulated automated driving

Introduction: Novice young adult drivers are at higher risk of being involved in an accident. Many studies have studied young adult drivers’ risk-taking behaviors under manual driving conditions. However, limited studies have examined novice young adult drivers’ fatigue during driving. Such issues could be more prominent in automated driving conditions. Studying novice young adult driver fatigue development under automated driving could provide a better understanding of the young adult driver’s crash factors, and in turn, prevent the accidents. Therefore, this study is designed to understand the novice young adult driver’s fatigue under automated driving. Method: In this study, 16 participants from novice young adult drivers (≤19 years old) and experienced middle-aged adult (≥21 years old) driver groups were recruited for a 1.5-hour automated driving task. The subjectively rated fatigue and discomfort questionnaire and electrocardiogram were used to measure fatigue development. Results: The results showed that novice young adult drivers developed fatigue faster and more severely than experienced middle-aged adult drivers under automated driving. Specifically, novice young adult drivers had a higher heart rate reduction and higher subjective ratings on the factors of over-drained, drowsy, uninterested, stiff joints, tense muscles, and numbness as compared with experienced middle-aged adult drivers. Novice young adult drivers were found to have an earlier onset of mental fatigue than experienced middle-aged adult drivers at 30 min of driving, while their physical fatigue was found to have a later onset at 60 min and 90 min of driving. Conclusions: Novice young adult drivers develop both physical and mental fatigue earlier than experienced middle-aged adult drivers during automated driving. Practical applications: The result suggests that fatigue alarm features should be considered when designing automated vehicles for novice young adult drivers.