Impact of Chevron Alignment Sign on Driver Stress on Horizontal Curves: A Simulator Study

The chevron alignment sign is an important element of curve delineation devices, and it mainly allows for better visibility when approaching the curve and provides positive guidance while navigating through a curve. However, few researches in China have been conducted to study its effects on drivers’ stress. This current study, based on a driving simulator experiment, focused on testing the effectiveness of chevron alignment sign on driver stress; meanwhile, researchers also tested if the function of chevron signs on driver nervousness was affected by curve roadway geometry (i.e., curve direction and curve radius). Thirty drivers participated in the experiment and the data of heart rate and their subjective feeling were collected through an AKF2 dynamic multi-parameter physiological recorder and through their verbal reports, respectively. The scenarios used in this experiment consisted of twelve different horizontal curves with combinations of chevrons presence, curve radius and curve direction. The results showed that in sharp-radius curve, drivers’ stress tended to be at a lower level and thus their heart rate was relatively low when chevrons were presented and the drivers’ perceived safe speed was higher. However, with the increased of the curve radius, the result was opposite. Therefore, the effect of chevrons was significant in sharp curve, and decreased with the increased of the curve radius.