Abstract

This driving simulation study compared differences in driver’s takeover time (TOT) and subjective workload for obstacle avoidance under different conditions of road complexity and attention distraction in in a level-3 automated driving. Participants were divided into two groups: young drivers in their 20s and older drivers aged 65 or older. Attention distraction was induced by performing a non-driving task (NDT) during autonomous driving, and road complexity was manipulated by varying the number of vehicles surrounding the drivers’ vehicle. The main findings and implications of this study are as follows. First, drivers’ TOT was significantly delayed in the NDT condition compared to the non-NDT condition during automated driving, and in the congested traffic condition compared to the clear road condition. Furthermore, the level of mental and physical workload during obstacle avoidance through manual driving after control takeover was significantly higher. Second, this tendency was particularly pronounced in the older driver group compared to the younger driver group. The results of this study suggested that older drivers may experience increased difficulties in safe and effective avoidance regarding obstacles ahead of their vehicle when visually and audibly distracted on congested roads.