Analysis On Urban Traffic State Based On Big Date

Accurate traffic state analysis is the prerequisite and foundation of traffic management,traffic guidance and traffic control.Analysis of urban traffic state must rely on the development of traffic information collection and data processing technologies.Comprehensive traffic data collection based on video detection technology and microwave detection technology can obtained the number of running vehicles on urban road network and travel speed.Based on above data,the analysis method of urban traffic state is studied,and the main research contents as follows.(1)Based on checkpoints data,the OD(origin-destination)of urban motor vehicle was studied.Anomalous data was eliminated by detection times of license plate.Distance(DIS)of adjacent records of the same car,minimum travel speed(Vmin),maximum travel speed(Vmax)and minimum time interval of two trips(τ)were used to separate the travel path.And Hangzhou was taken as an example to illustrate the evaluation of each parameter method.(2)A method was proposed to calculate number of vehicles running on urban road network based on checkpoints data.Concept of accumulative production and cumulative attraction was introduced.Formula for calculating the number of vehicles was deduced based on trip OD.Dynamic description model of the number of vehicles running on urban road network was established,and it’s forecasting function was proved.(3)Based on MFD,The traffic state analysis method was studied.Number of vehicles running on urban road network,average density of the road network and average travel speed of the road network were taken as the parameters of macro traffic flow.Relationship between the parameters were fitted,analyzing and calculating the optimal travel speed(Vm)of the road network and the optimal number of vehicles running on urban road network(Nm).According to Vm and Nm,the traffic flow status of the urban network was divided into general state and congested state respectively.(4)Traffic characteristics of expressway was analyzed,including the main service area,the average travel distance and the time-space distribution characteristics of expressway.(5)The fuzzy C-Means algorithm(FCM)was used to divide traffic state of the bottleneck.According to the fundamental diagram(FD),the traffic flow state of expressway was divided into free flow,stable flow,congested flow and blocked flow.