Reduction of travel distances through slotting, location arrangement and optimized order routing

Warehouses are important in a supply chain as they serve several entities of the supply chain: customers, manufacturing facilities, retail stores, etc. This research studies a warehouse to improve its overall performance with an emphasis on reducing the total travel distances during the order picking process. It is well documented that nearly 55% of the operational cost of a warehouse is attributed to order picking. There are several factors which affect the total travel: layout of the warehouse, storage policy, order picking strategy, etc. This research redesigns the layout, assigns items to logical locations, and routes the orders to be picked in order to reduce the total travel distances and in turn reduce the amount of time taken to retrieve items or fulfill customer orders.;The warehouse considered in this research consisted of only a few racks and most of the items were stored on the floor and stacked one over another. The warehouse itself is an old factory building that contains many poles and walls that get in the way of storing and retrieving items. The warehouse uses a random storage policy, zone picking, a class based storage system, and an alphanumeric order routing system. A combination of the physical layout of the warehouse and the random storage policy has caused long picking times. By adopting a dedicated location policy, grouping items into families and redesign of some of the locations in the warehouse shows a possible reduction of 33% in the amount of time it takes to pick an item. Through the application of linear programming along with a column generation approach, capacitive multi-route solutions to pick an order were created. The results, in terms of total distance traveled to pick an order, from the column generation approach was compared to the current practice in the warehouse. Several real life customer orders were chosen to compare the two approaches. An experimental study conducted shows an average decrease in total travel distance of 28% when compared to the methods used by the company.;This research successfully shows how a column generation approach can be used in determining order picking routes in a warehouse. The findings of this research helped the warehouse to fill customer orders in shorter time, use the warehouse space more efficiently, and improve the efficiency of the order pickers.