Forming, scheduling and routing field service teams for multi-skill tasks with priority levels

In this research, we study the multi-skill workforce scheduling and routing problem that exists in all service operations that provide services in customer premises. The problem originates from a real-life operational problem, faced by the electricity distribution companies on a daily basis, requiring efficient assignment of field service personnel to tasks. The problem aims to assign the tasks at different geographical locations with different priorities and skill level requirements to teams of technicians who have different skills. For the solution of the problem, firstly, a matematical model that have two priority objective function is developed. At the first priority level, the objective function is minimize the makespan of the weighted jobs by priorities. At the second priority level, the objective is to minimize total daily operational costs, including travel costs, overtime costs, and penalty costs of late tasks. It has been observed that as the size of the problem grows, the optimization model can not provide a solution to the acceptable optimal range at acceptable time. Therefore, a multi-phased heuristic is proposed that produces quality solutions in a short time for large-scale realistic problems. In the first phase of the heuristic, the teams are formed through a team building procedure. In the second phase, a greedy-based approach is applied to assign tasks to the teams in accordance with their skills. In the last phase, the daily routes of teams are identified. The effectiveness of the heuristic is assessed using both randomly created and realistic problem instances.