Study On Separation Technology Between Passenger Vehicles And Trucks On Multi-lane Expressway

With the increasing proportion of highway freight transportation in China,the influence of mixed traffic on road capacity and traffic accidents is becoming more and more significant.Based on the differences of the dimensions and dynamic performance of buses and trucks,the construction of separating trucks from passenger vehicles will become the future development trend.The research on separation of passenger cars and trucks started earlier in foreign countries.Domestic research on separating trucks from passenger vehicles mostly draws lessons from foreign achievements.Due to the difference of road traffic characteristics between China and foreign countries,it is necessary to study the passenger vehicles and trucks separation technology according to the road conditions in China.In this paper,the multi-lane expressway is taken as the research object,and a series of problems about the separation of passenger vehicles from trucks are studied systematically.In this paper,the capacity calculation model of passenger vehicle lane,the mixed traffic lane and truck lane is established,and based on this model,the separation setting conditions of passenger vehicles and trucks are proposed.Based on the analysis of the measured data,a speed density model suitable for the characteristics of road traffic composition in China is established,and then the traffic capacity calculation formulas for the passenger vehicle lane,the mixed traffic lane and the truck lane are established;This paper puts forward the passenger vehicles and trucks separation setting mode suitable for China's expressways;Based on the capacity of different lanes,combined with the separation setting mode of passenger vehicles and trucks,the calculation model of the total capacity of the road is established,and the setting conditions are put forward.Through the establishment of the cellular automata model of different passenger vehicles and trucks separation modes,the specific operation law of traffic flow is discussed,and the rationality of the proposed separation conditions is verified.The setting technology of connecting transition section of different passenger vehicles and trucks separation modes is put forward.According to the different traffic characteristics of the transition section,this paper analyzes that the main factors affecting the traffic flow stability are weaving operation and lane changing operation.For the weaving operation of traffic flow,the capacity calculation formula of the weaving section is constructed,which includes the length of transition section,the ratio of weaving flow,the number of one-way lanes and the number of truck lanes.Taking the three level of service(LOS)traffic volume which reaches the maximum capacity of the transition section as the boundary condition,the minimum value of the connecting transition section is determined;For lane changing operation,the lane change model is established on the premise that the vehicle is in the most unfavorable lane,and the minimum value of the transition section is proposed.This paper puts forward the exit setting technology of passenger vehicles and trucks separation section.Combined with the operation characteristics of passenger vehicles and trucks,it is analyzed that the main factor affecting the operation of export traffic is the barrier effect produced by trucks.The two-dimensional parameters for identifying the barrier effect are determined,and the condition of barrier effect is defined by off-line clustering.According to the barrier effect of trucks,a calculation model of the critical insertable gap value is established.Then,the calculation model of the maximum diversion traffic volume of passenger vehicles and the average waiting time model of waiting insertable gap are established.Finally,the maximum split traffic volume of passenger vehicles,the recommended length of separation opening section in the same direction,and the recommended length of the end position of the split opening from the split point in the same direction are obtained.The paper puts forward the entrance setting technology of passenger vehicles and trucks separation section.Based on the barrier effect of trucks and the theory of critical insertable gap,the calculation models of the maximum confluence traffic volume in the primary and secondary merging areas are established,and the interaction among bus,truck and ramp traffic systems is discussed.Taking the average section speed and average delay as the evaluation indexes,the relationship between the three systems is further quantified,and coordinated control method of three systems is proposed.The entrance setting forms of different passenger vehicles and trucks separation modes are put forward,and the suggested length of the acceleration segment?the codirectional isolation opening segment,and the end of the acceleration segment to the beginning of the codirectional isolation opening segment are obtained.This paper provide a theoretical basis for the construction of separating trucks from passenger vehicles,and can systematically guide the setting of passenger vehicles and truck separation.