Ambulance service facility location problem

In this paper an ambulance service facility problem is considered in an urban area with a polygonal shape. The objective of this research is to locate the facility under bi-criteria. One criterion is to minimize the maximum weighted sum of distances measured by A-distance in the route which passes from the facility to the hospital by way of the scene of accident. The other is to maximize the preference function of the facility site. Usually an optimal site that optimizes both criteria does not exist and so we seek some non-dominated sites for the facility after defining notion of non-dominated site.