Cross-docking is a practice in logistics of unloading materials from an incoming semi-trailer truck or railroad car and loading these materials directly into outbound trucks, trailers, or rail cars, with little or no storage in between. This may be done to change type of conveyance, to sort material intended for different destinations, or to combine material from different origins into transport vehicles (or containers) with the same, or similar destination.
Cross-Dock operations were first pioneered in the US trucking industry in the 1930s, and have been in continuous use in LTL (less than truckload) operations ever since. The US Military began utilizing cross-dock operations in the 1950s. Wal-Mart began utilizing cross-docking in the retail sector in the late 1980s.
In the LTL trucking industry, cross-docking is done by moving cargo from one transport vehicle directly into another, with minimal or no warehousing. In retail practice, cross-docking operations may utilize staging areas where inbound materials are sorted, consolidated, and stored until the outbound shipment is complete and ready to ship.
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Retail cross-dock example: Using the cross-dock technique, Wal-Mart was able to effectively leverage their logistical volume into a core strategic competency.
Cross-docks in practice are generally designed in an "I" configuration, which is an elongated rectangle. The goal in using this shape is to maximize the number of inbound and outbound doors that can be added to the facility while keeping the amount of floor space inside the facility to a minimum. In 2004, Bartholdi & Gue demonstrated that this shape is indeed ideal for facilities with 150 doors or less. For facilities with 150-200 doors a "T" shape is more cost effective. Finally, for facilities with 200 or more doors the cost minimizing shape will be an "X".[1]
Making the Move to Crossdocking, Maida Napolitano and the staff of Gross & Associates, 2000 copyright, www.werc.org