Link Travel-time Collection Method Based On GPS Equipped Floating Car

With the sharp increase in the number of cars, the problem of traffic congestion is getting worse. Traffic congestion leads to travel delays, traffic accidents, poor environment, resulting in enormous economic losses. In recent years, with the development of computer and communication technologies, the technologies of traffic conditions identification and vehicle navigation have become new thoughts to solve traffic congestion. Being different with traffic control technology, traffic conditions identification and vehicle navigation technologies are essentially carry out the coordination of non-mandatory to impending trip in order to distribute traffic demands rationally, and to assist other traffic management measures effectively for solving the problem of traffic jams.Travel time is a intuitive parameters for reflecting road congestion, which can provide basis for decision-making to traffic conditions identification and vehicle navigation system. Comparing with other traffic parameters detection technologies, GPS-FC technology is no need to invest in road infrastructure and the scope of data acquisition are unrestricted. Additionally, GPS/GIS/communications technologies used in the vehicle monitoring system provide the basis data and system framework for GPS-FC technology. Thus, the current study on GPS-FC technology has had the objective conditions.Based on the status quo, combined with the author's point of view, this article has explored and improved the GPS-FC technology from the following aspects:1) The directional link dividing method can be used to collect travel time distinguishing different turns of traffic flow and sub-link dividing method can be used to collect travel time distinguishing different places of a link are designed considering user needs. At the same time, in order to overcome the puzzle of turning weight determining for the vehicle navigation technology, the connectivity relations of road network expression method is researched. In addition, in order to give full consideration to all kinds of factors to running situation of vehicles, a method for determining GPS data intervals are studied.2) In order to improve the quality of GPS data, first of all, a GPS data pre-processing method is researched. Among them, the stopping state identifying method is designed for improving the speed and accuracy of map-matching, and provide the basis for assessing and processing the quality of individual link travel time data. In addition, in order to improve the effectiveness of the longitudinal map matching, a map-matching algorithm independent GPS-based positioning is put forward, and verified using GPS/GIS data.3) First of all, the methods of individual link travel time estimation are designed. The direct and indirect algorithm for estimating individual link travel time are verified using GPS/GIS data, and then the comparison is done using travel time data obtained.4) Initially, the method of average travel time of floating cars estimation is designed using individual link travel time data. And a method of average travel time of traffic flow estimation is designed using average travel time of floating cars, the focus is determining the quantitative relationship. In addition, the verifications are done using simulated data.The main innovations of this paper are as follows:1) The directional link dividing method can be used to collect travel time distinguishing different turns of traffic flow and sub-link dividing method can be used to collect travel time distinguishing different places of a link are designed. And the connectivity relations of road network expression method is researched combining the characteristics of directional link;2) Through the analysis of influencing factors, the main indicators needing to be considered for determining GPS data intervals are defined, and then the methods for determining GPS data intervals are designed using individual link travel time data;3) A map-matching algorithm independent GPS-based positioning is designed considering the spatial distribution form of GPS positioning errors;4) The direct algorithm for estimating individual link travel time are improved considering the characteristics of the vehicle running;5) A comparison method between two algorithms of individual link travel time estimation is designed based on data analysis;6) A method of individual link travel time quality evaluation and controlling is designed according to the influence of stopping state;7) A method of quality evaluation and controlling for average travel time of floating cars is designed according to the influence of data fluctuation;8) A method of average travel time of traffic flow estimation is designed congsidering the quantitative relationship between average travel time of traffic flow and average travel time of floating cars.