The Theory And Methodology For Evacuation Traffic Network Aggregation Design

All kinds of emergency events occurred frequently all over the world in recent years. In order to reduce the negative impact of the emergency events and improve the regional evacuation efficiency, the corresponding emergency evacuation plans have been made in various regions. The processing of the emergency evacuation network has an important influence on the effectiveness and rationality of traffic emergency evacuation plan. Network aggregation can enhance the operation efficiency by reducing the calculation time without sacrificing the accuracy of traffic distribution. The aggregated processing of emergency evacuation network focus on qualitative analysis, which lead to the lack of quantitative calculation model and poor applicability under emergency situation at the present stage. Therefore, it has an importantrealistic significance to the effective implementation of the emergency evacuation plan that establishing a urban evacuation network aggregated method applicable to emergency conditions according to the characteristics emergency evacuation traffic conditions.This paper is based on classification theory of the urban road network and divide-devacuation network into emergency evacuation road network and emergency evacuation branch network. It also determines the design framework for the aggregated layered network of emergency evacuation according to their respective network characteristics and combination of the applicable scope of the traditional methods, which means different method was applied for different networks. Emergency evacuati-on roadnetwork plays a maneuverable role during evacuation and the changes of its network structure are hard to implement evacuation traffic organization. Because of the main road extraction, an evacuation main aggregation model which aims at minimizing the oversaturation should be used to carry on processing to the network. Evacuation branch network undertakes the accessibility in its process. Evacuation road network lead the evacutees to the emergency evacuation roadnetwork and reduce the cost of evacuation time. Therefore, network abstraction method is used to evacuation branch network aggregation in this paper.Finally, it takes the evacuation network aggregation in the condition of typhoon in BeiLun District of NingBo City as the research background in this article and compared the aggregated network with origin network. The results show that the model and method proposed in this paper can improve the efficiency of evacuation traffic distribution without sacrificing the oversaturation of the network and evacuation time cost, and supply a reliable network for emergency evacuation plans.