Abstract: The particularity of emergency facilities determines that emergency facility location,as a special type of facility location problem,must pay more attention to timeliness.According to the levels of emergency services,different factors are taken into account when modeling emergency facility location.Actually,there are often several levels of emergency facilities in our real life.This article proposes a hierarchical emergency facility location model based on a hybrid model of p-center and p-median model,in which a pcenter model is applied to the lower level services and a p-median model is applied to the higher level services.In accordance with the real situation of emergency services,this model improves the distance measurement by replacing the Euclidean distance with transport network distance.Finally,the hierarchical emergency facility location model is applied to the medical facilities location in Putuo District of Shanghai.

Key words: emergency facility location, hierarchical model, traffic network distance