Driver stress as influenced by driving maneuvers and roadway conditions

Excess stress can influence driving performance and increase crash likelihood. The level of stress can also vary based on different driving conditions. Past research has not differentiated among these conditions, but rather has focused on individual driver differences. The goal of this study is to understand how different driving tasks and roadway conditions may influence the stress perceived by drivers. This was accomplished using data from a survey that assessed drivers' stress under various road, traffic and weather-related scenarios. Factor analytic techniques were used to find groups of driving scenarios that generate similar stress levels in drivers. The results revealed four scenarios that were categorized in terms of (1) weather, (2) visibility, (3) interactions with other drivers, and (4) driving tasks. Ordered logistic regression models were then used to determine the effect of socioeconomic characteristics, trip behavior, and crash history for different stressful driving scenarios. Increases in stress with these four factors were influenced by age and gender, with females being more likely to report higher levels of stress than males. The effect of age varied in that older drivers generally reported higher stress levels, except when interacting with other drivers. Drivers with a history of crashes reported significantly higher stress levels when there was limited visibility, in adverse weather, and while performing common driving tasks. The results revealed that stress depends not only on driver characteristics, but also on the specific driving environment.