Warehousing with a human touch: Exploring and leveraging the role of human factors in order picking

Abstract

Warehouses are under enormous pressure to process customer orders in an efficient manner. On the one hand, the demand for logistics services continues to rise due to economic growth, while on the other hand, several societal trends complicate its ability to capitalise on these growth opportunities. Globalisation, increasing customer expectations, and disruptive market events are just a few examples of factors that pose significant challenges for the warehousing sector in fulfilling customer demand. The combination of rising customer demand and a business environment with many challenges forces warehouses to operate as efficiently as possible in pursuit of sustained competitiveness. Many of today’s warehouses still heavily rely on human order pickers for processing orders, although the order picker job is one that faces a significant shortage. High-performing order pickers are difficult to retain, yet they are crucial for the execution of warehouse tasks. Previous research has predominantly focused on optimising warehouse processes, with very limited (or even no) attention to their implications on order pickers. This doctoral thesis changes this paradigm and places human order pickers at the core of the planning and execution of warehouse processes; the aim of this dissertation is, therefore, to develop system interventions that not only enhance operational efficiency but also improve worker well-being to ensure that warehouses remain both economically and socially sustainable. The main contributions of this doctoral thesis are as follows. First, an overview is provided of how the current academic literature integrates human factors into order picking planning decisions. Subsequently, the findings of this state-of-the-art literature review are compared with insights derived from semi-structured interviews with both order pickers and their supervisors from various warehouses. This cross-comparison offers empirically validated research opportunities for future studies and highlights that mainly the psychosocial aspects of warehouse work remain underexplored in current scientific literature. The second contribution taps into the gap between practical needs and academic literature. Specifically, a system intervention is developed with the goal of involving employees in operational warehouse decisions, aimed at enhancing their perceived job satisfaction. The developed participatory system is tested in multiple warehouse environments -both in a real-world company setting and in a laboratory environment- and is shown to yield both psychosocial (e.g., job satisfaction) and physical (e.g., perceived fatigue) well-being benefits, without compromising productivity. A third contribution delves deeper into the effects of the developed system; in particular by examining whether these effects are sustained over a longer period of time. In many experimental warehouse studies, participants are typically exposed to an intervention only for a limited duration. This short exposure period could potentially lead to an incomplete and biased view of the true impact of the intervention. The developed system was implemented for a sustained period of time (6 months) in a real-world warehouse and the results indicate that the positive effects indeed persist over time. A final contribution of this doctoral thesis is substantiating the potential of participatory work systems to have an impact that exceeds the one reported in current academic literature. Through the use of analytical and simulation models, it is shown that managers can somewhat steer the impact of a participatory system, without reducing the degree of employee participation. By designing the participatory system more intelligently, its effectiveness in improving productivity and well-being could be further improved. Ultimately, this thesis concludes with a large set of recommendations for future research aimed at holistically improving order picking systems, in order to enhance both productivity and the well-being of order pickers.