Research On Traffic Safety And Control Technology Of Long Downhill Tunnel

In recent years,China's transportation network has developed rapidly.Due to the geographical environment of mountainous area,tunnel connection is often adopted,which not only saves resource consumption but also is convenient and fast.With the development of highway tunnel construction,long downhill tunnel safety accidents occur frequently.The existing static speed control method can not meet the safety requirements of long downhill tunnel.Therefore,this paper studies the dynamic speed limit control technology of traffic safety in long downhill tunnel,and provides theoretical basis and technical support for improving the traffic safety status of long downhill tunnel.First of all,this paper makes statistics on the accident data of expressway tunnels over the years,classifies and analyzes the statistical results according to the accident characteristics,and obtains the main influencing factors of safe driving in long downhill tunnels.Through the research,it is found that the number of accidents and the risk of accidents will be reduced if the driving speed is properly reduced.According to the safety and comfort of highway driving,the reference value of speed limit in long downhill tunnel of expressway is determined.Secondly,the influence of visibility,road friction,tunnel length and tunnel slope on vehicle speed is analyzed,and the correction coefficient of each factor to the reference value of speed limit is calculated.In order to avoid the low speed limit caused by repeated correction of the reference value,the analytic hierarchy process(AHP)is used to distribute the weight of the influencing factors to obtain the correction coefficient of the comprehensive environment.Based on the cellular transmission model,the traffic flow model of long downhill tunnel is established by modifying the comprehensive environmental factors.In order to reduce the dispersion of vehicle speed in the tunnel and effectively improve the traffic safety of vehicles in the tunnel,the variable speed limit control is added to the established model,and the variable speed limit traffic flow model of long downhill tunnel under comprehensive environmental conditions is established.Thirdly,the composition and control process of the variable speed limit control system for long downhill tunnel are designed.Considering the safety and traffic efficiency,the objective function is constructed,and the optimal speed limit value is solved by particle swarm optimization algorithm under the coordination constraints of variable speed limit.Finally,taking the actual environment of Tanyugou tunnel in Beijing as an example,the traffic flow of typical highway long downhill tunnel is simulated by VISSIM software,and the traffic safety control experiment is completed by programming with visual basic language,and the control effect of variable speed limit of long downhill tunnel under the influence of comprehensive environmental conditions is evaluated.The results show that through the implementation of variable speed limit control on Highway Long Downhill tunnel,vehicle delay time,queue length and speed difference of adjacent sections are greatly reduced.Under the premise of ensuring traffic efficiency,the driving safety in long downhill tunnel is effectively improved,which provides theoretical and technical help for traffic safety and control technology of long downhill tunnel of high-speed highway in the future.