Optimization of maintenance tasks of spatially distributed assets with non-preemptive overtime

Abstract

ABSTRACT A major challenge in maintenance scheduling is how to avoid excessive maintenance costs due to labor and overtime. In maintenance of utilities in commercial buildings, the repair technicians have to travel between the maintenance sites to perform maintenance tasks under non-preemption constraint. In such a maintenance, and due to geographically distributed assets in occupied buildings, travelling will consume a proportion of the available work time. To find a good balance between the number of technicians, the number of selected tasks and the right routing between the tasks along with overtime considerations, a MILP model is presented in this study. Here, joint decisions that will minimize the cost of labor, transportation and overtime in the form of time schedules and daily routes are addressed. Using AMPL and CPLEX to formulate and solve the model, case studies from real industry in Uae have been solved for testing and validation. The results showed a remarkable reduction in costs due to presenting optimal technician routes, low use of overtime and small workforces. The model can be cast into a commercial package, which offers maintenance providers a custom solution for maintenance activities that are characterized by their high frequency, short duration and spatially distributed sites.