Study On Traffic Organization And Key Index Of Expressway With Combined Type Cross Section

With the increase of highway traffic volume in China year by year,higher requirements are put forward for the capacity of expressways.The existing four-lane and six-lane expressways are difficult to meet the growing traffic demand,and multilane expressways need to be built by construction or expansion.When the number of lanes is ten and above in both directions,it is not suitable to set up an integral section on the expressway,but a combined type cross section should be set up.However,there is a lack of research on the layout form and key indexes of the combined section expressway in China,and it is also blank in the design standard.Therefore,this paper studies the traffic organization and key indexes of the combined section expressway,which is of great significance to the construction and safety management of multi-lane expressway in China.By collecting and consulting the related research literature and engineering examples of the combined section expressway,the definition and typical section form of the combined section expressway are defined,and the characteristic elements of the combined section expressway are put forward.By analyzing the purpose of the traffic organization of the combined section expressway,this paper puts forward the characteristics and advantages of the main traffic organization mode of the combined section expressway(passenger and freight separation type and long distance and distribution separation type).Combined with vehicle types and vehicle characteristics,the classification method of passenger cars and freight cars on the combined section expressway of passenger and freight separation type is studied and determined.Based on the vehicle characteristic parameters and the physiological characteristics of the driver’s mind,using the theories of vehicle dynamics and traffic engineering,the width values of each component of the cross-section of the composite section expressway were studied and determined.Study the connection mode between inner and outer lane.For the integral section,by analyzing the influence factors of the position of the opening of the same direction divider,the minimum net distance between the same direction separator opening and the interchange is studied by using the lane change theory,and the minimum length of the same direction separator opening is studied by analogy of accelerating and decelerating lane setting.For the separated section,based on the definition and classification of the transfer ramp,the design speed and cross-section layout of the transfer ramp are studied by analogy with the interchange ramp.The net distance between the transfer ramp and the interchange is simulated by using traffic simulation technology and traffic conflict technology.The traffic conflict rate is determined as the evaluation index of traffic conflict severity,and the relationship between traffic conflict rate and net distance is analyzed after weighted processing of traffic conflict data,and the reasonable net distance value is determined within the acceptable range of traffic conflict severity.It is compared and analyzed with the research results of lane change theory,and finally the recommended minimum net distance between the same direction separator opening,the directconnected transfer ramp,the semi-direct-connected transfer ramp with the interchange is obtained.