Evaluation Method Of Traffic Congestion For Beijing Suburb Based On Floating Car Data

With the development of Beijing,the population density in the suburbs has increased significantly,resulting in an unbalance between traffic supply and demand,and traffic congestion has become the norm.With the carrying out of easing traffic congestion in Beijing,the municipal government puts forward the principle of "traffic congestion monitoring,analysis and management over the five rings",aimed at using the traffic congestion assessment method,which is successfully applied to the six districts of urban,to test and evaluate the traffic operation status of suburbs.However,due to the differences in the size and layout of the road network,and the sample size of the floating car between urban and suburbs,it is difficult to apply the method of traffic congestion evaluation of urban to suburbs directly.It is an urgent problem that how to establish the traffic congestion evaluation method which is applicable to suburbs.The paper is put forward under such an circumstance.In view of the above problems,this paper unfolds from four aspects of dividing the congestion level thresholds,selecting the congestion evaluation roads,screening the congestion evaluation periods and weighting congestion indexes by VKT weight,respectively.Firstly,the road congestion level thresholds of floating car data are divided according to the traffic flow theory,and following issues are demonstrated respectively in the process(1)The thresholds differences between traditional and new energy taxi are greater than 5km/h,so it is necessary to weight both;(2)The thresholds differences between the far and near suburbs are smaller than 3km/h,so the thresholds can be unified.Secondly,this paper bases on the method of maximum likelihood and interval estimation to verify the uniformity between the congestion intensity perception data of traffic participants and the thresholds of traffic flow theory at 95%confidence level,and the results show that the two are highly consistent.Then by comparing the thresholds of urban and suburban areas,obtains that:(1)Under the same congestion level,suburban thresholds are significantly greater than the urban.(2)There are smaller span between thresholds of urban,however,the suburbs are the opposite.Thirdly,due to the characteristics of' suburban traffic operation and data collection,in order to ensure the accuracy of congestion evaluated,the paper select the key roads of suburbs based on population activity thermodynamic map,furthermore,rhe article defines spatial coverage to screen the congestion evaluation roads.Lastly,the paper checks.the congestion evaluation periods though return times.The section and period should meet the standards of the above indexes before the congestion evaluated.Then,the paper analyses the time granularity of suburban traffic congestion evaluation,and combining with related researches,determine the index is 1 hour.According to the index,to integrate the speed of the selected roads,and transform the integrated speed into the traffic index of[0,10],bases on the congestion thresholds,moreover,weights the congestion index by VKT weights.Finally,though cases analysis,it is proved that the applicability of the established congestion evaluation method.The paper chooses the traffic conditions in Tongzhou District,Changping District and Huairou District for working day,weekend,the day before holiday and holiday to carry out congestion evaluation.The results show that:(1)traffic in the three selected suburbs,Tongzhou District is the best,followed by Huairou District,Changping District is the worst.(2)Although there are serious congestion in the individual sections of suburbs,no serious congestion in the overall traffic.(3)The evening peak traffic of the day before the holiday is affected by holiday travel greatly.