Motorcyclists' Safety on Expressways: Subjective and Objective Evaluations

This study objectively and subjectively investigates the factors influencing motorcyclists' safety on expressways. The relationships between motorcyclist stress while driving on expressways and potential influencing factors including traffic situations, road geometries, and wind conditions are also investigated. Data collected from a historical crash database and through a field experiment were used for the analyses reported in this paper. A special device was used during the experiment to measure the motorcyclists' stress levels and to collect required information such as location, speed, and surrounding traffic. Statistical analyses conducted on motorcyclists' subjective safety perception, obtained through a questionnaire survey, highlighted that the degree of risk from surrounding vehicles was the most significant influencing factor, followed by vibration caused by road surface asperity. Furthermore, the analysis on motorcyclists' stress level indicated that the significant influencing factors are the proportion of traveling time on the climbing lane, the proportion of traveling time in which the adjacent left lane is occupied by a heavy vehicle, and the variations of instantaneous speeds.