Performance evaluation of service territories

Field service support is important for certain products, such as computer systems and copiers, for which service performance has a significant impact on market share. In this paper, the problem of field service operations and its important characteristics are described. Models are developed to assist the field service manager in the evaluation of performance of a given service territory with heterogeneous machines scattered (typically, nonuniformly) over a region repaired by a traveling serviceman. Given the probability distributions of machine uptimes and repair times, and travel times between machine locations, models are developed to approximate the overall-travel time distribution. This is used in existing queueing models to determine the performance measures, such as mean downtime per machine and server utilization. The results of the models are tested by simulation and observed to provide good estimates for the measures of interest. These models are eventually intended to help in making decisions on territory design and staffing levels.