Warehouse Item Picking: A P-dispersion Approach to Minimise Blocking

Order picking is one of the most time-and cost-intensive warehouse operations, and its efficiency can be significantly reduced by worker blocking, especially when mechanical handling equipment restricts simultaneous access to adjacent locations.This paper presents a case study of a Czech retail distribution centre where blocking frequently occurs despite wide aisles, due to access constraints created by forklifts and electric pallet trucks.To reduce congestion, we propose a storage assignment method based on the p-dispersion problem, aiming to maximise the separation of frequently accessed items and thereby minimise collision probability.A simulation-based evaluation shows that the optimised assignment reduces total order-picking time by 11.5% compared to the original layout.The findings suggest that incorporating blocking considerations into storage assignment policies can significantly improve operational performance without requiring investments in additional equipment or layout modifications.