Replanning working time under annualised working hours

Abstract

Using annualised hours (i.e., distributing working hours irregularly over a year) grants a company the flexibility needed to meet the seasonal nature of demand. Since annualised hours can lead to a worsening of the staff's working conditions, many laws and collective bargaining agreements contain constraints that affect the distribution of working time. In the past few years, efforts have been made to develop methods for optimally solving planning problems involving annualised working hours. However, to our knowledge, the problem of replanning work time with annualised working hours has not been addressed in the literature. Herein, we explore different ways of achieving said replanning, using mixed-integer linear programming models. Two main objectives are considered: the cost of the new plan and the stability of the scheduling of workers’ working time. Solving the models for various scenarios yields the quantitative information that is needed to replan an annualised hours system.