Development of a pedestrian evacuation model for urban chemical release emergency

Chemical release emergency occurred in cities easily cause large scale injuries in short time. Evacuation and shelter-in-place are two alternative response activities. In china, emergency manager usually prefer the former because many buildings are not well airtight. Also, the proportion of the residents evacuating by walk and by vehicle is high. Evacuation route has a crucial impact on the effectiveness of the evacuation activities, and health consequences can be used to weigh up its good and bad which has relationships with its traveling distance and time, as well as the concentration of the toxic gases around the route. This paper presents a model that evaluates alternative evacuation routes and find out an optimal one. The model can give a report which contains detailed traveling directions for each node having evacuation demands in a created evacuation network. A hypothetical chemical release contingency is given for demonstrating the application of the model, and the results are shown.