An Investigation into Picking Norm Times and Well-Being: Fatigue-Aware Order Picking Planning

High turnover and shortage of order pickers are great concerns in the logistics industry. Manual order picking is physically demanding and impacts workers' well-being. Recently, employers have agreed to adjust picking norm times to improve pickers′ well-being. However, the literature lacks understanding about the impact of picking times on pickers' well-being. We propose a novel approach to order picker planning that considers physical fatigue of workers as a measure of concern for well-being. The model we develop generates batches of orders, assigns and sequences them while considering the impact of picking time on physical fatigue. Crucially, we consider the behaviour of pickers and assume that workers are empowered to take spontaneous breaks when they reach critical fatigue levels. An adaptive large neighbourhood search algorithm is proposed to address the problem and conduct extensive experiments to generate managerial insights. The results of traditional retail scenarios show that imposing strict time targets can harm well-being and hurt picking efficiency. Increasing picking norm times by only 1% can reduce picker fatigue by 10% on average. Furthermore, warehouse design decisions can have an impact on physical fatigue of workers. This research demonstrates the critical need to reevaluate operational strategies and prioritise worker empowerment to achieve sustainable order picking.