Research On Characteristics And Index Of Urban Road Traffic Demand

Traffic operation is the result of traffic demand and traffic supply(urban road network).On the premise of relatively stable urban road supply,traffic demand is the real internal factor determining traffic operation.How to accurately describe traffic demand,including total demand and space distribution characteristics,is one of the keys to analyze and solve traffic congestion.Based on the data-driven research method,this study analyzes and grasps the temporal and spatial characteristics of traffic demand in urban road network,and puts forward a model that can dynamically reflect the characteristics of road network traffic demand,which provides a basis for the management of traffic demand and the planning,construction and improvement of road network.Firstly,this study combs the existing research on traffic demand and determines the traffic demand analysis framework based on the characteristics of road network flow;Secondly,aiming at missing data of traffic flow detector,the sample expansion technology and geographic weighted regression model are used to repair the missing traffic flow data,which overcomes the problems of unbalanced traffic flow samples and spatial correlation,and the influencing factors of lane traffic volume are discussed and analyzed;Thirdly,based on the definition of urban road traffic demand in this study,a section traffic demand index model is proposed,The relationship between demand index and traffic operation is studied(vehicle speed and traffic operation index),and on this basis,the division of traffic demand level is completed;based on the road section traffic demand index model,taking Yangpu District of Shanghai as an example,the spatial equilibrium and spatio-temporal correlation characteristics of regional traffic demand are analyzed by using variation coefficient,spatial correlation theory and temporal correlation analysis method;finally,the traffic demand is analyzed Based on the influence mechanism of traffic demand spatial imbalance on traffic operation efficiency of road network,a regional traffic demand index model of "entropy weight method" is proposed and verified by the zoning data of Yangpu District.The main research results are as follows:(1)The spatial correlation of traffic samples is analyzed by using the spatial correlation theory,and verified by the measured data of Yangpu District,Shanghai.The results show that there is a spatial positive correlation between high traffic and high traffic and between low traffic and low traffic in each period.This conclusion also further verifies the spatial statistical model for missing traffic the necessity of modeling.On this basis,a comprehensive method combining sample expansion technology and spatial statistical model is proposed to repair the missing traffic in the region,that is,a new sample expansion method based on spatial similarity is proposed to improve the problems of unbalanced spatial distribution and too small sample size of traffic samples,Based on the measured data of Yangpu District,Shanghai,the repair accuracy of the comprehensive method is verified by 10 times cross validation.The results show that this method can not only improve the prediction accuracy of the model,but also improve the interpretation ability of the independent variables of the model,and has good generalization ability;(2)The flow saturation of the road section is selected as the traffic demand index of the road section.Taking the measured data of Yangpu District of Shanghai as an example,the monotonic decreasing nonlinear relationship between the road section demand index of different grades of roads and the road section speed is analyzed by using the curve fitting method.Further,the straight line subsection fitting method is used to find out the mutation point of the speed fitting curve to complete the level division of the traffic demand index;(3)Taking Yangpu District of Shanghai as an example,the spatial balance and spatio-temporal correlation characteristics of regional traffic demand are analyzed by using the theoretical methods of coefficient of variation,spatial correlation theory and time series correlation analysis.The results show that the spatial distribution of regional traffic demand has great imbalance in each period(the variation coefficient values are more than 35%),and the imbalance degree in non peak hours is more serious than that in peak hours;in each period,the regional traffic demand has global and local spatial correlation;the time series of traffic demand in upstream and downstream sections have high correlation in value and change trend,and the traffic demand in upstream and downstream sections has high correlation in value and change trend There is no delay in potential;(4)The numerical simulation method is used to quantitatively analyze the impact mechanism of the unbalanced spatial distribution of traffic demand on the traffic operation of the road network in different road network modes,so as to lay a solid foundation for the definition of regional traffic demand index.The results show that when the road network layout and road hierarchical structure remain unchanged,the vehicle delay per kilometer of the road network increases with the increase of the imbalance of traffic demand When the layout remains unchanged,the negative impact of the imbalance of traffic demand on the operation efficiency of the road network decreases with the rationalization of the road hierarchical structure;When the road hierarchical structure remains unchanged,there is no significant difference in the negative impact of traffic demand imbalance on road network operation efficiency under different road network densities;(5)Based on the principle of "delay equivalence",fully considering the impact of traffic demand spatial imbalance and overestimating the actual traffic operation of the road network,the regional traffic demand index model is established by using the "entropy weight method".It is verified by the measured data of Yangpu District,Shanghai,and the results show that the "entropy weight method" While reflecting the regional traffic demand,the regional traffic demand index can accurately reflect the negative impact of the imbalance of traffic demand on the traffic efficiency of the regional road network.This paper focuses on the nonlinear characteristics and unbalanced distribution characteristics of traffic demand in urban road network.On this basis,a traffic demand index model is proposed to describe the characteristics of road network traffic demand.Through the verification of the case data of Yangpu District,Shanghai,the traffic demand index model has a high level of accuracy and applicability,and can provide a basis for the planning,construction and improvement of road network.