Multi-field coupling analysis on the driving risk of expressways in a rain and fog mixed environment

The winter rain-fog mixed climate is one of calamitous climates that seriously affect driving safety in foggy days. Through distinction between superposition of risk fields in foggy sections and multi-field coupling of risks, based on field theory, an analysis was made on the mathematical and physical characteristics of risk fields in foggy sections in a mixed climate, and a method of evaluating vehicle risks in a rain and fog mixed environment was proposed; in terms of climate and traffic flow coupling, in relation to risk field in foggy sections in a rain and fog mixed environment, a mathematical model was built, and verified through examples; finally, in combination with flow field and the theoretical model of interaction between risks, in a mixed environment, a correction formula for a single vehicle correction at any point was determined. The result showed that risk field superposition was to define the value at risk from macro point of view, and multi-field coupling was to make an analysis from the perspective of the micro physical characteristics of risk, and both field superposition and coupling must be considered in-depth analysis of the risk of driving on expressways in a foggy environment; in a real foggy environment, the factors that impact risk fields in foggy sections interacted with each other, between which there was a non-linear coupling relationship; risk fields in foggy sections were considered as scalar fields; due to the effect of driving speed, traffic flow and wind velocity, risk fields in foggy sections were of the characteristics of flow field; the above relationship of impact was defined, and an accident risk transfer function model that affects the interaction in connection with a single vehicle was built.