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PATROL CAR ALLOCATION MODEL - BACKGROUND

NCJ Number
48800
Journal
Management Science Volume: 24 Issue: 12 Dated: (AUGUST 1978) Pages: 1280-1290
Author(s)
J M CHAIKEN; P DORMONT
Date Published
1978
Length
11 pages
Annotation
A REVIEW OF POLICE PATROL CAR ALLOCATION MODELS WAS UNDERTAKEN BEFORE DESIGNING A COMPUTER PROGRAM TO ACCOMPLISH THE ALLOCATION FUNCTION ON THE BASIS OF TIME AND GEOGRAPHY.
Abstract
SEVERAL COMPUTER PROGRAMS EMERGED DURING THE 1970'S THAT EITHER WERE BASED ON OR SIMILAR TO THE RESOURCE ALLOCATION MODEL OF THE ST. LOUIS, MO., POLICE DEPARTMENT OR TO A PROGRAM DESIGNED BY RICHARD LARSON. THE LAW ENFORCEMENT MANPOWER RESOURCE ALLOCATION SYSTEM WAS THE MOST WIDELY KNOWN PROGRAM BASED ON THE ST. LOUIS SYSTEM BUT WAS TERMINATED AT THE END OF 1974. LARSON'S PROGRAM WAS A PRECURSOR TO THE FOLLOWING MODELS: A PROPRIETARY PROGRAM KNOWN AS THE POLICE RESOURCE ALLOCATION PROGRAM, A NEW YORK CITY POLICE DEPARTMENT RADIO MOTORIZED PATROL ALLOCATION SYSTEM, A PROGRAM DESIGNED FOR THE LOS ANGELES, CALIF., POLICE DEPARTMENT, AND A PROGRAM WRITTEN FOR THE ROTTERDAM POLICE DEPARTMENT. THESE PROGRAMS WERE ALL SIMILAR, ALTHOUGH EACH ONE HAD SEVERAL FEATURES THAT WERE ESPECIALLY DESIRABLE OR PARTICULARLY INADEQUATE. THESE VARYING FEATURES CONCERNED THE PROGRAM'S MODE OF OPERATION (BATCH OR INTERACTIVE), INPUT REQUIREMENTS, ASSUMPTIONS UNDERLYING CALCULATIONS, OR CAPABILITY TO TAKE CERTAIN PERFORMANCE MEASURES INTO ACCOUNT. ALL PROGRAMS CONSIDERED IN THE HISTORICAL REVIEW ALLOCATED PATROL CARS TO INDEPENDENT GEOGRAPHIC COMMANDS. EACH PRECINCT WAS MODELED AS A QUEUEING SYSTEM IN WHICH SERVERS WERE PATROL CARS AND CUSTOMERS WERE CALLS FOR SERVICE TO THE POLICE. QUEUEING STATISTICS WERE CALCULATED FOR THE COLLECTION OF PATROL CARS BY ASSUMING A STEADY-STATE SYSTEM WITH CALLS FOR SERVICE ARRIVING WITHIN PRIORITY LEVELS ACCORDING TO A POISSON DISTRIBUTION AND PROVIDING INDEPENDENT, IDENTICAL, AND EXPONENTIALLY DISTRIBUTED SERVICE TIMES. THE UNAVAILABILITY OF PATROL CARS FOR REASONS OTHER THAN CALLS FOR SERVICE WAS HANDLED IN THE PROGRAMS BY ARTIFICIALLY INCREASING THE ARRIVAL RATE OF CALLS OR BY ASSUMING THAT THE NUMBER OF SERVERS WAS SMALLER THAN THE NUMBER OF PATROL CARS. SOME PROGRAMS CALCULATED ADDITIONAL PERFORMANCE MEASURES SUCH AS TRAVEL TIME AND PREVENTIVE PATROL FREQUENCY. A GENERAL-PURPOSE PROGRAM KNOWN AS THE PATROL CAR ALLOCATION MODEL (PCAM) WAS DESIGNED AFTER REVIEWING VARIOUS PATROL CAR ALLOCATION PROGRAMS. PROVISION WAS MADE FOR WIDE USABILITY OF THE PCAM BY WRITING THE PROGRAM IN A STANDARD VERSION OF FORTRAN WITHOUT RECOURSE TO LANGUAGE FEATURES PECULIAR TO ONE COMPUTER SYSTEM. INSTALLATION WAS FACILITATED BY THE DYNAMIC ALLOCATION OF ARRAY STORAGE, ALLOWING THE PCAM TO ADJUST ARRAY DIMENSIONS FOR A PARTICULAR CITY AND TYPE OF ANALYSIS. CAPABILITIES AND FUNCTIONS INCLUDED IN THE PCAM AND EXAMPLES OF MODEL APPLICATIONS ARE DESCRIBED IN A SEPARATE ARTICLE. REFERENCES ARE INCLUDED. (DEP)