Research On The Real-time Routing Strategy For Unexpected Regional Congestion

Along with the rapid development of the modern traffic economics and the swift growth, The traffic congestion often occur in urban traffic networks, increasing the traveler’s travel time and cost. The existing researches about the routing for the traffic congestion in urban traffic networks, mainly focused on the single section or intersections, and researched the routing strategy for section congestion or intersection congestion, and have made many achievements. However, there is not always the single section or intersection congestion, but more serious regional congestion that multiple incident sections and multiple incident intersections are simultaneously blocked at certain times, and which is more difficult to dredge and deal with.Therefore, we research the real-time routing strategy for unexpected regional congestion to maximize reduced the loss by the regional congestion caused; these have important theoretical and practical value. According the limitations of the existing researches, in this paper, the regional congestion is defined, a parameter is presented, regional congestion factor, to measure the influence caused by the regional congestion in urban traffic networks, and analyzing the properties of the parameter, an algorithm be proposed, and then an example be given to verification at last. On this basis, by using online problems and competitive strategy, we study the real-time routing strategy for unexpected regional congestion in the urban traffic networks to maximize reduce the traveler’loss. Aim at providing the routing strategy and traffic induced basis for the traveler and the traffic managers.The major work and innovative achievements of this paper are as follows:Present the parameter that the influence of regional congestion to the urban traffic networks and the algorithm. According to the often appear of the regional congestion in urban traffic networks, we define it as the regional congestion by the possible shapes in practice, and analysis the different cases combined with the network topology characteristics and the cause. And then we present the parameter from the point of view that the minimum passing time will be changed form the node to other nodes in a network when regional congestion happened in a network, to measure the influence of regional congestion to urban traffic networks. And then, we analysis the properties of the parameter from the relationship of the shortest path trees of all nodes and the relationship between regional congestion and the shortest path tree of all nodes. Further, considering the shortest path tree of some nodes haven’t changed, the shortest path tree of some nodes only partly have changed, we design the algorithm, and analysis the time complexity. Lastly, taking the general freestyle city network as an example in china, Chongqing, to verify the parameter and the algorithm.Establish the real-time routing strategy for unexpected regional congestion, and analyze the competitive ratio. On the basis of defining the unexpected regional congestion, analyzing the keys that influence the real-time routing strategy for unexpected regional congestion, using the online problems and competitive strategy, aiming to maximum reduce the time lose of the traveler, we study the real-time routing strategy for unexpected recoverable regional congestion, giving the waiting strategy and greedy strategy, analyzing the competitive ratio of these two strategies, which is 1+h·α and τh, and study the real-time routing strategy for unexpected unrecoverable regional congestion, giving the full round strategy and the detour strategy, analyzing the competitive ratio of these two strategies, which is βh and 1+h·β*. The results indicate that, when the regional congestion is recoverable, the competitive performance of the waiting strategy and the greedy strategy don’t relate to the location of the regional congestion, which relate to the amount of the regional congestion, the former is liner increasing relation, the latter is geometry series increasing relation. When the regional congestion is unrecoverable, the competitive performance of the full round strategy and the detour strategy don’t relate to the location of the regional congestion, which relate to the amount of the regional congestion, the former is geometry series increasing relation, the latter is liner increasing relation.