Facility location: a review of context-free and EMS models.

EMS location models are those formulated to address specific problems of emergency medical services systems; context-free location models are those developed without reference to particular applications. The literature on these two types of public facility location models is reviewed, and the development of the maximal covering model from several earlier context-free models is described, with emphasis on problem statements and articulation of service objectives. An application of the maximal covering model to fire truck location points up the ability of this model to handle multiple objectives; its ability to compare alternative solutions gives it great utility for planning and evaluating EMS systems of a wide range of complexity. Potential applications of the maximal covering model are discussed regarding EMS problems involving multiple time standards and service objectives, location of special equipment, and siting of fixed facilities.