Research And Implementation Of Variable Speed Limit Control System For Mountain Highway In Rain And Fog

The complex road conditions,such as bends and ramps,of mountain highway are more likely to cause traffic accidents in rainy and foggy weather.Speed limit is an important way to guarantee the driving safety of mountain roads in rainy and foggy weather.However,the commonly used static speed limit methods are prone to reduce road capacity and cause traffic jams,which restricts the enhancement of traffic efficiency.In this paper,considering the impact of rainy and foggy weather and road characteristics on mountain roads,a variable speed limit control system for mountain roads under rainy and foggy weather is designed.The system can realize the data collection of rainy and foggy weather and traffic flow,the mountain road traffic flow simulation,speed limit calculation and speed limit release.Our research is of great significance to improve the driving safety of mountain highway in rainy and foggy weather.(1)According to the functional structure of the variable speed limit control system for mountain highway in rainy and foggy weather,the main requirements of the system are analyzed.In consideration of the problems in engineering design and on-site implementation,a four-tier system architecture,including perception layer,network layer,application layer and public layer,is designed to address the above problems.Moreover,the service-oriented software platform is given by the Dubbo distributed service framework.(2)Considering the influence of rainy and foggy weather and road conditions on traffic speed and capacity,the correction coefficients of traffic speed and capacity are proposed by introducing the traditional Cell Transmission Model,and the improved highway dynamic traffic flow model considering the factors of rainy and foggy weather and road conditions is established.Furthermore,the affect of variable speed limit on traffic flow is considered,the dynamic traffic flow model of mountain road is given under the control of variable speed limit.(3)By analyzing the principle of variable speed limit control,the working flow and overall structure of variable speed limit control strategy for mountain highway in rainy and foggy weather are determined.Considering the factors of rain and fog,mountain road conditions and drivers’ dynamic vision,the constraint condition of maximum speed limit value is established by modifying the traditional stopping sight distance model.Meanwhile,the calculation method of speed limit value is proposed based on the adaptive genetic algorithm.(4)Using Dubbo distributed framework,the software platform of variable speed limit control system for mountain road in rainy and foggy weather is designed.The functions,including the data monitoring of weather and traffic flow,the estimation of highway traffic flow of rainy and foggy condition,and the release of variable speed limit information are achieved.The results of test and application show that the system can realize the intelligent speed limit of the mountain highway in rainy and foggy weather,and it is of great significance to improve the driving safety.