Study On Setting Method Of Interchange Ramp Connection Mode Of Three-leg Interchange On Multi-lane Highway

The vehicle will pass through the interchange bifurcation,confluence connection part and influence area in the process of driving between the main line of the road and the cross road,and the vehicle will change lanes frequently in this area.There is a complex connection form on the left turn ramp of three turnout crossing.When the traffic flow is designed,it will affect the road capacity and reduce the traffic efficiency.The existing specifications stipulate the qualitative setting conditions of the connection mode when the left turn traffic flow is the primary and secondary traffic flow.Therefore,this thesis studies the quantitative criteria for the setting conditions of the ramp connection mode of the three-leg interchange,defines the primary and secondary traffic flow,and provides quantitative reference for designers.Firstly,the thesis introduces the definition and classification of interchange,the definition of main line and crossing road,the connection form of three-leg interchange ramp on the basis of the existing research results of divided and combined influence area,and analyzes the traffic flow characteristics of divided and combined influence area and the influencing factors of three-switch interchange ramp connection mode,including the number of lanes,traffic volume,traffic composition,highway grade and design speed,road plane alignment,etc.Secondly,the separation and confluence mode and lane change behavior are studied.By calculating the construction distance of separation and confluence,the recognition distance of signs,the redistribution distance of traffic flow,and the safety confirmation distance,the length of the influence area of different road forms in separation and confluence areas is obtained.Then,based on the similarity between the traffic flow operation characteristics of the divided and combined influence area and the weaving area,through the theoretical calculation model of the service level of the weaving area,the saturation of the weaving area,the speed difference between the average speed of the weaving area and the free velocity and the service level of the weaving area are calculated,and the definition conditions of the primary and secondary traffic flow under different design speeds and different lane numbers are obtained.Then,VISSIM simulation software is used to establish the road model of one-way two-lane and one-way three-lane in the confluence area,and the simulation parameters are determined.The traffic volume at different design speeds uses the three-level service level to design the traffic capacity,and the relationship diagram between the cross-section traffic capacity of the confluence area and the different steering ratios is established.The mutation point of the cross-section traffic capacity scatter diagram is used to determine the proportion of the left-turn traffic as the main traffic flow,and the rationality of the theoretical calculation conclusion is verified.Finally,VISSIM simulation software is used to define the smaller traffic volume of the intersection road when the right-in-left-out semi-direct connection can be used at the exit of the three-leg interchange and the left-in-right-insemi-direct connection can be used at the entrance.This thesis puts forward the quantitative setting conditions of three-leg interchange ramp connection mode of multi-lane highway,and obtains the definition conditions of primary and secondary traffic flow and the recommended value of less traffic volume of crossed highway.The research results have important theoretical value.The conclusion provides reference for designers and evaluators and has certain practical value.