A Patrol Car Allocation Model: Capabilities and Algorithms

A computer program has been designed for specifying the number of police patrol cars that should be on duty in each geographical command of a city at various times of day on each day of the week. It incorporates, by user option, nearly all the desirable features of earlier allocation programs, together with several improvements. It calculates performance statistics for the current allocation of patrol cars or any allocation proposed by the user. In addition, it has two prescriptive capabilities: (1) determining the minimum number of patrol cars needed during each tour in each command to meet specified constraints on performance measures, and (2) allocating a specified total number of car-hours by time and/or geography so as to optimize one of several available objective functions. The main technical innovation in the model is that it allows one tour in each day to overlay two other tours. A heuristic algorithm allocates car-hours when there is such an overlay tour; it is optimal when the overlay tour has the same duration as the tours it overlays.