A new warehouse design problem and a proposed polynomial-time optimal order picking algorithm

In this study, we propose a new design problem that relates to orientation of cross aisles in warehouses. In this problem, the main orthogonal cross aisle, which is very common to be seen in warehouses to facilitate travel between locations, is planned to be designed as discrete manner such as tunnels along picking aisles. Hence, the problem of locating these tunnels along picking aisles so as to increase efficiency of order picking operations, which is one of the most costly and the most related operations with the order delivery time in warehouses, is propounded. Additionally, we develop a new dynamic programming based polynomial time algorithm to calculate optimal length of order picking tour in this new design problem. Hence, this algorithm provides very quick solutions even for large pick list sizes. The computational performance of this algorithm is compared with Held-Karp branch and bound algorithm, which is a well-known algorithm for travelling salesman problem. Last, we solve an example problem and explain how the algorithm is implemented to generate optimal tour.