Employee scheduling in service industries with flexible employee availability and demand

We consider an employee scheduling problem arising in service industries with flexible employee availability and flexible demand. In the system to be planned, there is a given set of service requirements and a set of employees at any time. Each employee belongs to one of various skill levels, each service requirement specifies the requested employee skill level and the timing of the service delivery, and each requirement has a weight that indicates the importance of that requirement. Employees have individual flexible contracts with the organization, which are characterized by weekly/monthly contracted work hours, days the employee is available for work and availability of overtime. Furthermore, there are regulations on maximum work hours and minimum rest requirements of employees enforced by the government and the labor union. The problem that we investigate is to generate an assignment of employees to service requirements which (i) ensures that the maximum weighted number of service requirements is met, (ii) satisfies government and labor union regulations, (iii) honors individual employee contracts with minimum deviation from the contracted work hours, and (iv) ensures a fair balance between employee schedules in terms of work assignments on holidays. We model the problem as a mixed-integer programming problem and discuss a reformulation strategy, which allows us to solve practical problems in a reasonable amount of time. We also report our experience in a large health-care organization in Belgium. (C) 2016 Elsevier Ltd. All rights reserved.