Study Of Macroscopic Fundamental Diagrams Based On License Plate Recognition Data

With the increasing demand for transportation,urban traffic problems are becoming more and more serious,and traffic congestion is showing a trend of point-lane-surface expansion.In order to solve urban traffic problems,improve the traffic operation environment and rationalize the allocation of traffic resources,it is necessary to grasp the level of urban traffic operation from an overall perspective,and then make corresponding traffic management measures and control strategies.The macroscopic fundamental diagram(MFD)can well describe the overall traffic operation of the road network,this paper focuses on the MFD,studies the spatial-temporal features of the MFD based on a large amount of license plate recognition data(LPRD),and constructs a stable and effective MFD model.The main research in this paper is as follows:(i)In this paper,the method and process of LPRD cleansing and correction is investigated,the problem device is identified,and effective license plate number data and vehicle travel time data that can be used for the study are obtained.The quality of the data is then further analyzed in terms of both the accuracy of the road traffic flow based on the license plate number data and the accuracy of the link travel time estimation based on the vehicle travel time data.(ii)In this paper,the MFD model is constructed using the processed LPRD,the relevant traffic flow characteristic parameters are obtained,and the errors of the MFD are analyzed.(iii)In this paper,the MFD models at different levels in the study area is constructed,and the effect of time varying characteristics in the same traffic parameters between different objects on MFD is studied,and the results show that the MFDs constructed by objects with similar time varying characteristics can only reflect the overall traffic operation.On this basis,this paper gives a method for aggregating similar traffic characteristic sections in the road network,which leads to an effective MFD.(iv)This paper analyzes the distribution characteristics of single-day MFD under longterm observation.On this basis,the convergence characteristics of the multi-day MFD under different selection of LPRD of a variety of different days are compared by statistical methodology.The results show that the MFD at low density have high stability,the stability of the MFD at high density increases with the number of statistical days data,and the used data from multiple consecutive working days can quickly and efficiently obtain stable MFD with small errors.