Study On Design Indexes Of The Speed Change Lanes Of Interchange On Expressway With Separation Between Passenger Cars And Trucks

With the continuous improvement of the transport infrastructure and the sustainable development of transportation industry in China,the proportion of road freight transportation continues to increase,and the trend of heavy haul freight truck is obvious,the construction of expressway with separation between passenger cars and trucks will become the future development trend.Interchange as an important part of expressway,is always the accidentprone area of expressway.With the increase of traffic volume,the interferences between passenger cars and trucks are aggravated,and the severity of accidents is also increased.Interchange with separation between passenger cars and trucks is an important form to reduce the interferences between different types of vehicles.At present,there are relatively more studies on the main line of passenger cars and trucks separation expressway at home and abroad,and less studies on the design indexes of the speed change lanes in interchange with separation between passenger cars and trucks.Therefore,this paper takes the speed change lanes as the research object to study its main design indexes of interchange on expressway with separation between passenger cars and trucks.Based on the analysis of the setting methodes of passenger cars and trucks separation expressway,the design control factors of interchange with separation between passenger cars and the trucks were studied,the common forms of passenger cars and trucks separation interchange and the recommended setting forms of speed change lanes were put forward,as well as the typical representative vehicles of the interchange,the design speeds of the main lines and the ramps both were determined for passenger cars and trucks respectively.Secondly,based on the measured datas of UMRR chain radar in the diverging and merging areas of sample interchanges,the driving characteristic parameters were studied by mathematical statistics method of passenger cars and trucks traffic flows in the diverging and merging areas.Based on the driving characteristics of vehicles on acceleration lanes,the passenger cars and trucks separation acceleration lanes were divided into acceleration,waiting and triangular transition sections,and according to kinematics theory and traffic flow theory,the calculation models of acceleration lane length were established.Based on the deceleration behavior of vehicles on deceleration lanes,the running state of the vehicle was demonstrated which basically obey the secondary deceleration theory,on the basis the calculation models of deceleration lane were established in the interchange with separation between passenger cars and the trucks.The key characteristic parameters in the calculation models of acceleration lane and deceleration lane of passenger cars and trucks separation interchange were demonstrated and analyzed by different types of vehicles,and the design indexes of speed change lanes of passenger cars and trucks separation interchange were put forward.Finally,based on the influencing factors of the design index of the operating speed transition section,the calculation model of the design indexes of the operating speed transition section were established in passenger cars and trucks separation interchange,and the curvature radius at any point and lengthes of the operating speed transition section were studied and put forward to meet the requirements of safety driving.The research results of this paper can provide a theory for the future construction of interchange on expressway with separation between passenger cars and trucks in China,and also provide a good reference significance in this field.