Study of Alternative Approaches to Motor Vehicle Maintenance

摘要

As part of a productivity improvement effort, Wilmington, Del., experimented with various approaches to maintaining police patrol vehicles. Wilmington operated a demand driven system for its 81 police vehicles; i.e., with the exception of routine maintenance such as oil changes, the vehicles were driven until they broke down. Officials believed that maintenance could be improved by employing the following methods: (1) using planned preventive maintenance, (2) contracting with the private sector for maintenance work, or (3) holding individual officers responsible for maintaining their vehicles. Corresponding groups and a control group involving a total of 29 vehicles (mostly Belairs and Chevelles) were formed to test these hypotheses. A number of methodological problems, however, limited the usefulness of data obtained in the experiment: the sample was too small, there were no Belairs in the control group, the cars in the sample were not homogeneous, assignment to groups was probably not random, preventive maintenance schedules were not always followed, gas stations rather than garages performed preventive maintenance, mileages varied, and recordkeeping was probably inaccurate. Notwithstanding these limitations, the analytic approach used by Wilmington should be useful for performing similar analyses in other cities, and suggestions for eliminating data limitations are included. The data suggest that in - house preventive maintenance is superior in terms of cost per mile, total cost, cost per incident, and minimizing time out of service. Tables and forms accompany the text.