Research On Expressway Warning Method And Speed Limit Strategy In Foggy Days

With the continuous development of social economy,China has made great efforts to build expressways and other transportation infrastructure.With the increasing mileage of expressways,the incidence of traffic accidents on expressways also rises.Among them,the highway traffic accident rate caused by severe weather conditions such as fog accounts for a large proportion,and the traffic accident rate is often more serious in foggy days.In order to reduce the accident rate of expressway in foggy days,this paper studies the expressway traffic safety warning and speed management in foggy days.First of all,the literature and theories related to the research status at home and abroad,the characteristics and influencing factors of highway traffic accidents,and the formation mechanism of fog,etc.are sorted out by the literature and data method,and the space-time characteristics of highway traffic accidents under fog conditions are analyzed.Secondly,based on traffic flow theory and traffic flow data of foggy expressway,a real-time traffic conflict model is constructed by regression analysis method.In addition,the k-means clustering method is used to divide the number of traffic conflicts into safe state,medium risk state and high risk state,and the highway early warning system is constructed in foggy environment,and the model method is verified.Then,according to the warning level,the speed limit standard of expressway under foggy conditions is proposed under the premise of comprehensively considering the factors such as drivers’ reaction time,weather visibility,sliding friction coefficient and longitudinal slope of the road,and the speed limit model based on safe distance is established.Finally,the speed limit standard is simulated and verified by Car Sim software.The results show that the constructed warning method of display status classification can effectively identify the dangerous traffic conditions on the expressway in foggy conditions,and can timely release the set warning status.The proposed speed limit value can ensure the driving safety of vehicles in low visibility conditions.It provides a theoretical reference for relevant departments in highway safety management in foggy environment.