Distributed service networks encompass various facilities with which we have daily contact. In the public sector they include, for instance, ambulance, fire, and police services; in the business sector they include maintenance and repair services, road services, courier services, and the like. Policy making problems in distributed service networks can be clearly classified into a number of hierarchical levels. The levels are distinguished by the time horizon of the problem, by the amount of cost involved in the implementation of a solution, and by the political implications of the solution. This top-down classification is typical of what is known as the "systems approach," advocating that the direction of the analysis of complex systems should be from the whole to the details. The top-down classification consists of the following categories of policies: 1. Zoning: How should a network be partitioned into subzones? 2. Station location: Where should service stations or service units be located? 3. Resource allocation: What amount of resources should be allocated to the stations? vii viii Preface 4. Dispatching, routing, and repositioning: What is the optimal dis­ patching policy, what are the optimal routes for nonbusy units, and under what circumstances is it worthwhile to reposition a certain idle unit? A top-down approach implies that each of the problems is solved separately; however, the solution of a higher-level problem sets constraints on problems at lower levels.