Study On The Influence Of Urban Expressway Truck Mixing Rate On Traffic Operation Status

With the rapid development of city scale and urban transportation,urban expressways,as the aorta of urban road transportation system,bear a lot of transportation needs.At present,traffic congestion is severe during expressway peaks,and the increase in truck mix-in ratios has further adversely affected traffic operation status and reduced road capacity.Therefore,based on the typical urban expressway traffic flow data,this thesis explores the impact of the truck mixing rate on the traffic operation status,so as to provide theoretical support for improving the urban expressway traffic operation status and improving the road service level.The thesis selects Nanping Expressway in Shenzhen as the research object,follows the ideas of data investigation,model construction,cluster analysis,and simulation verification,and adopts a mathematical method combining qualitative and quantitative research.The specific research contents are as follows:(1)Through the field traffic survey,we obtain traffic flow data such as urban expressway traffic flow,truck mixing rate,speed,density,etc.,and analyze the urban expressway traffic flow time,spatial distribution characteristics,vehicle speed distribution characteristics and truck mixing traffic characteristics.(2)Use SPSS statistical software to take speed as the dependent variable,density and truck mixing rate as independent variables,and use regression analysis to establish the urban expressway traffic flow regression model.(3)The fuzzy c-means clustering algorithm is programmed by Matlab,and the traffic operation status is quantitatively divided into free flow,stable flow and congested flow using the two traffic operation status evaluation parameters of speed and density as the clustering index to obtain the speed and density of each traffic operation status range value.(4)Combined with the urban expressway traffic flow regression model,the speed and density range of the clustering results are used as intermediate variables to determine the impact of the range of different truck mixing rates on the traffic operation status.The results show that:: ? When the truck mixing rate range is(0.16,0.32),and the density range is(0pcu/km,7.17pcu/km),the truck mixing rate has little effect on the traffic operation status,and the urban expressway traffic operation status is free flow;? When the truck mixing rate range is(0.32,0.38),and the density range is(7.17pcu/km,9.49pcu/km),the truck mixing rate has a certain interference with the traffic operation status,and the urban expressway traffic operation status is stable flow;? When the truck mixing rate range is(0.38,0.56),and the density range is(9.49pcu/km,17.25pcu/km),the truck mixing rate has a greater impact on the traffic operation status,and the urban expressway traffic operation status is congested flow.(5)Based on the actual traffic flow data,the Vissim simulation software is used to calibrate the traffic flow parameters,by setting different traffic flows and truck mixing rates,and selecting the speed as the evaluation index,the impact of different truck mixing rates on the traffic operation status is verified.Through theoretical research and simulation analysis,the thesis reveals the influence of urban expressway truck mixing rate on traffic operation status,and determines the influence range of truck mixing rate under different traffic operating status.The results of the thesis provide a theoretical basis for the in-depth study of the impact of urban expressway trucks on the operation status of traffic flow,and have practical significance for the construction of urban expressway management mechanism and improvement of operating efficiency.