Research On Strategy And Adaptability Of Lane Restriction Of Eight-lane Freeway

China's freeway mileage and traffic demand have been increasing year by year,and many freeways are reconstructed to eight lanes.As traffic characteristics of eight-lane freeway are more complicated,certain lane restriction strategies are usually adopted to separate vehicles of different types.It is of great practical significance to study the method and adaptability of eightlane freeway to improve traffic safety and efficiency.The features of eight-lane freeways are analyzed.Roadway features are analyzed,including road facility and traffic management.Traffic characteristics are analyzed,such as volume,speed and headway distribution.Crash patterns are analyzed,including crash type and causes.A vehicle classification method oriented to lane restrictions is proposed.Based on the existing vehicle classification criteria,detailed classification criteria are proposed to preliminarily divide vehicle types.Speed,headway distance,and rear-end spacing are selected to reflect the driving behaviors of vehicles.Kolmogorov-Smirnov Z tests are conducted to analyze the difference between different types.For the convenience of traffic management,vehicles are sorted into four types.Lane restriction strategies are studied.After analyzing the purpose,influencing factors,principles and types of lane restrictions,a variety of representative lane restriction strategies are proposed for eight-lane freeways,such as exclusive lanes.An eight-lane freeway microscopic traffic simulation model based on vehicle classification is established.Simulations are performed using VISSIM software,and model parameters are set according to observed data.The parameter calibration experiment is designed by using the Latin orthogonal experiment method,the simulation model is corrected,and the validity of the model verified.The adaptability of lane restriction strategies of eight-lane basic freeway segments is analyzed.Indicators are chosen considering safety and efficiency.Weightings of indicators are determined based on entropy method,and different lane restriction strategies are evaluated comprehensively.Simulation experiments are conducted under different traffic compositions,and effects of different strategies are compared,determining the best strategy for each level of truck ratios.