Study And Realization Of The Methods For Estimation Of Real-Time Traffic State Based On Floating Car Data

Real- time traffic state is the basis of the Advanced Traffic Information Systems (ATIS).It can help to implement the traffic control and management, dynamic route guidance, improve the travel condition and provide the reference for resident trips, bus dispatching and urban planning.Traditional traffic detector (such as loop detector, microwave detector, radar detector) plays an important role in the detection of traffic flow. But there are many drawbacks in the detection. For example, the traveling time and road speed is not available, the road space to cover by detectors is limited, and the cost of installation and service is too high. In recent years, the floating car technology is widely applied to collect traffic information, especially the vehicle terminal based on GPS is installed on the floating cars, like buses, taxis and logistic vehicles. These floating cars running on the urban road network provide a number of real time traffic data, such as vehicle location, vehicle speed, vehicle condition, etc. The floating car data has many advantages, such as high precision, large amount of data, wide space of coverage, economy and convenience.Based on analyzing the research of present situation of traffic parameters, I propose the improvement method to directly estimate and fusion method, and do data validation.According to the estimation method of travel time model needs, first of all, the collected data should be map matched. This paper adopts the acquisition technology based on 3G. the collected data is screened through speed selection rules, and then combined with the GIS electronic map road information. Then the collected data matches to the road by the projection map matching algorithm.Secondly, analyzed the direct estimation method and indirect estimation method which are commonly used based on floating car data, an improvement of the direct estimation method is proposed. After comparing the difference between estimate values and the true value, a fusion method is proposed. It improves the estimation accuracy of travel time.Finally, on the basis of theoretical research, I completed the analysis, demand function design, database design of the real-time traffic information calculation system based on floating car.