Research And Implementation Of Traffic Automatic Incident Detection Algorithm For Freeway

With the rapid development of urban rapid transport, urban road network structure becomes more complex and traffic incidents also become much more. Because there is a lot of high-speed traffic on urban freeway, which is more closed than ordinary urban road and more crowded than inter-city freeway, urban freeway will congest heavily if the incidents can't be cleaned in time. So an accurate, rapid detection of the happening of traffic incidents has a very important practical significance to the unobstructed network. Traffic automatic incident detection (AID) is an important part of freeway emergency management system, and high-performance automatic incident detection algorithm can significantly improve the system's effect. The thesis stems from a research content of Beijing Natural Science Foundation-funded projects named as "Research on Traffic Flow Model and Key Technologies of Traffic Guidance for Beijing Urban Freeways" (8052016) and also is a sub-project of "intelligent traffic management system in Beijing" which is a project from Beijing STONE Intelligent Transportation System Integration CO., LTD.After an extensive literature review of existing AID techniques, the paper introduces the key points of existing algorithms and finds there is not an absolute perfect algorithm. On the basis of the analysis of traffic incidents' impact and according to the temporal and the two-dimensional spatial abnormal variability of traffic flow as a result of traffic incidents, the paper proposes an easily applicative AID algorithm based on 3D integration. The design idea is that when a traffic incident happens, the algorithm integrates the change of volume and speed of adjacent lanes in the horizontal dimension, the change of occupancy of upstream and downstream section in the vertical dimension and the change of occupancy levels of the flow-occupancy model in the temporal dimension to alarm incidents. The paper also describes design ideas and working procedures of integrated judgment module and parameters update module in the details.Then in order to verify the algorithm, the paper analyses the validity and practicability of the algorithm with the detector data from Beijing freeway, and the result shows the integrated algorithm can meet basic needs of practical application. And on the basis of the clear system objective, the paper uses the Visual C++ and Oracle technology to program an applicative software. The research ideas and the algorithm proposed in this paper is a method exploration of traffic automatic incident detection algorithm of fixed detectors and may provide certain theoretical reference.