# Mental Health and Safety Assessment Methods of Bus Drivers
## 1 Introduction  
In China, road traffic accidents are a serious social problem, and personal factors, vehicles, road conditions, and environmental conditions may lead to traffic accidents. Previous research results confirm that about 86% of traffic accidents in China are caused by human factors [1]. As of 2021, there are 589,961 public-transport vehicles in operation in China [2], with a large number of bus drivers. As special practitioners integrating the characteristics of technical post and service post, bus drivers require proficient driving skills, good personalities, and healthy psychological levels to ensure the safety of people's lives and properties. However, in recent years, major traffic accidents of commercial vehicles have occurred frequently in China due to the poor mental state and personality characteristics of drivers. Therefore, the mental health and safety of drivers have become hot, difficult issues in road traffic safety. Human mental health includes two closely related and distinguishable parts: mental state and mental adjustment ability, and the premise of mental health is the harmony and unity of personality characteristics. The SCL-90 scale is an internationally recognized psychological measurement scale with high reliability and validity for distinguishing healthy people from patients with physical and mental illnesses. It contains a wide range of psychological symptoms and can accurately describe the psychological symptoms of subjects in different degrees [3]. Recently, this scale has been used in mental health at home and abroad to investigate the mental health of different occupational groups, especially in assessing the mental health of drivers, and the effect is ideal [4]. However, the SCL-90 scale mainly measures a person's mental state in a certain period, ignoring its ability to regulate. At the same time, personality tests widely popular in the world are compiled according to trait theory. The Y-G personality scale breaks through their respective limitations becauseit takes into account the advantages of type theory and trait theory. The reliability and validity of the scale are relatively high, and the number of questions is relatively moderate. Therefore, it has been widely used in evaluating human personality. However, the Y-G personality scale mainly reflects a person's stable psychological adjustment ability, and relatively ignores the psychological state. Therefore, the Y-G personality scale and SCL-90 scale were combined to evaluate the personality and psychology of bus drivers in the work. Besides reflecting the degree of symptom pain in a certain aspect of drivers and the breadth of the personality characteristics of the assessed object, it can screen the factors affecting the drivers' psychology. On the other hand, most use statistical methods and logistic regression models in analyzing traffic accidents based on the psychological factors of drivers [5; 6; 7]. Although revealing some drivers' psychological influencing factors in traffic accidents, these methods ignore the relationship between accidents and influencing factors and the degree of influence of each factor on the occurrence of accidents. Moreover, they cannot reflect the complicated logical relationship among traffic accident causes, the occurrence of traffic accidents, and consequences of traffic accidents, in lack of analyzing the impact and sensitivity of traffic accidents from different demographic characteristics, psychology, and personalities. Therefore, the work applied the Bayesian network model to the analysis of drivers' mental health and established a Bayesian network model for evaluating bus drivers' mental health and traffic safety. The model visually displayed the correlation between various influencing factors in a complex system, and the model's accident prediction results were accurate. Key factors of a traffic accident were quickly identified to find the most likely combination of factors.