Study On The Risk Of Commercial Bus Traffic Safety Based On The Fault Tree Analysis

Road transportation of commercial bus is an important way of transport passengers and its safety directly affects people’s life. Once commercial bus traffic accident happened, it would cause significant casualties and property losses because of its particularities such as long transport distance, large capacity, and difficult management etc. It has great theoretical and practical application significance to analyze and identify the commercial bus traffic safety risks and dangerous sources, further to guide potential hazards check and risks assessment within transportation companies, and to decrease traffic accidents effectively.According to four subsystems of commercial bus transportation system: participants, vehicles, environment, and management, drivers’ particularities on traffic signal processing, illegal driving, speeding driving and bad driving habits are studied; the importance of main safety devices and safety technologies of commercial bus is analized; important influencing factors in nature environment, road environment and traffic environment are discussed; management contents and requirements of passenger transportation enterprises are listed. Then, information of the commercial bus fateful traffic accidents happened from 2009 to 2014 in China is collected. The distribution of the accident forms is analyzied, and the relationships between single factor of human-vehicle-environment system and accident number, single factor and accident form, interacting factors and accident form are analyzied deeply. Five main fault tree models such as vehicle falling, overturn, frontal crash, rear-end crash and side crash are built, and fault tree models are analyzied qualitative by solving the minimum cut sets and structure importance, dangerous situations of different accident forms and dangerous degrees of dangerous resources are discovered.. At Last, the dangerous resource identification table of commercial bus fateful traffic accidents is built, which has 30 dangerous resources and 7 attributes, and its application strategy is put forward.The study results show as follows: roads near with water, gutter, valley and cliff, high subgrade, speeding driving, and improper operation are the main influencing factors for vehicle falling. Illegal overtaking, improper operation and ice snow covered pavements are the main influencing factors for vehicle overturn. Speeding, illegal occupying-road, overload driving, and general curve and slope are the main influencing factors for frontal crash. Other vehicle unsafety, fatigue driving, bad visibility, driving without license, braking fault and improper operation are the main influencing factors for rear-end crash. Speeding, other vehicle lengthways unsafety and driving without license are the main influencing factors for side crash. The dangerous resources identification table could instruct practical safe production of passenger transport enterprises effectively, reduce the potential accident possibility, and be the important basis for security evaluation and related security system development.