The Real-time Traffic Status Acquirement And System Assessment Based On Taxis GPS Trajectory Data

With the development of economy and the progress of science and technology, motor vehicles become the leading transport vehicles. However, the rapid growth of the road facilities in urban fall behind the growth of motor vehicles because of the limited space resource, which make traffic congestion become a worldwide phenomenon and social problem. Intelligent Transportation System (ITS) is the most effective way to solve the problem of traffic congestion. Taxis are typical vehicles in the road traffic flow. Since the improvement of GPS positioning precision and the popularity of equipment, real-time traffic information acquired through huge, density and wide covered taxi GPS trajectory is an important and effective way in the research of ITS. Based on this background, this paper mainly studied on the real-time traffic status system which obtains the road conditions information based on taxis GPS trajectory data.Firstly, the paper introduces the research background and the currently available GPS floating vehicles system, as well as the traffic parameter estimation algorithm of domestic and foreign which focus on studying taxis GPS trajectory data. Then it introduces the research area and the data structure of data sources, including map data and taxis GPS trajectory data. Data preprocessing clears the interference data by analyzing characteristics of redundant data, invalid data and noise data. After that the paper focuses on the types and methods of the existing map matching, and proposes a simplified map matching method to improve the matching efficiency. It unified the coordinate of map data to the GPS data, then determines the road which GPS data belongs to by calculate the shortest distance between point and line by vector method, finally confirm the direction the vehicle is traveling on the road according to the orientation of the road and the orientation of the instantaneous velocity of the vehicle. Besides, the paper describes the common traffic flow parameters, and selects the mean travel speed as the parameter of traffic congestion, if there is data missing or unavailable, determine the status of traffic using historical data and real-time data integrated. Finally, it designs and develops a real-time traffic status system according to above. To verify the accuracy difference of the system of this paper, Baidu map, and Gaode map, it selects a study area, obtains the reality traffic status by capturing videos of several days and periods, and introduces the level deviation parameter. The results show that there is little difference between the system and Baidu map and Gaode map. Therefore, it well reflects the real-time road condition.