The design principles and success factors for the operation of cross dock facilities in grocery and retail supply chains

[摘要] ENGLISH ABSTRACT:The dissertation reflects the research done on the design principles and success factorsfor the operation of cross dock facilities in grocery and retail supply chains.The cross dock is a particular facility in the supply chain where goods are receivedfrom suppliers, sorted without storage of the goods, and then efficiently moved todownstream customers.Cross docks are not a new operation. However, the use in high volume grocery andretail operational capabilities is poorly understood and is not uniquely defined. Theproblem is that cross docks are often seen as extensions of warehouses. The samepersonnel, systems and processes are applied and the efficiency potential of the crossdock is not achieved.Warehouses are orientated towards storing the full range of product and allowing thepick to be done from this storage buffer to provide any or all of these products to acustomer. Cross docks will only handle products that are used in larger quantities andthat are sent to most, if not all, the customers. The cross dock is therefore distinct andvery different from the traditional warehouse.The published research tends to focus on the technical aspects of the cross docklayout. This research is primarily in the scheduling of the trucks into the yard of thefacility; the allocation of trucks to specific doors of the facility; and the allocation ofdoors to receiving and despatch functions within the facility. Very little information orresearch reflects the design principles and success factors for the cross dock and itssupply chain. The only classification of the cross dock in the literature is whether thebarcode is added to the item before or after receipt at the cross dock.For this research work a literature survey was conducted and five major operationswere reviewed, in South Africa and the USA. The research empirically drew logicalconclusions, which were tested in the operations and found to be correct. This allowedthe design principles and success factors to be determined for a successful cross dock.The research extends the knowledge of the cross dock operation and design: -• A new classification for the feasible types of cross docks in the supply chainwas developed. Three factors are shown to be of primary importance: -o Where in the supply chain the identification of specific items for acustomer is done;o Where the sort is done for the items to be delivered to a customer; ando Whether the supplier is providing one product or multiple products tothe sort.From these three factors, eight potential classifications could be defined.However, only three practical types of cross dock can be determined fromthese eight alternatives. These are named in this research as Cross DockManaged Load (CML); Joint Managed Load (JML); and the SupplierManaged Load (SML).The cross dock is far more effective than the warehouse when the total work(excluding inventory) is considered. The earlier in the supply chain theproduct is identified for the use of the entire downstream supply chain, themore effective will be the total supply chain. Thus the greatest supply chaineffectiveness possible is with the SML, then the JML and finally the CML.• The operation of a cross dock is very similar to a continuous manufacturingprocess. There is no buffer of stock to decouple the inbound and outboundprocesses, and the operation takes place in a restricted area. However, in theretail chain, the workload alters with different orders and different days. Dailyload differences vary by as much as 90%. This results in vastly differentworkloads and variations of throughput. This is similar to a batch operationwith highly variable workloads between batches. The literature recommendsthe use of Just in Time (JIT) practice for cross docks. This is inappropriate asits primary requirements are continuous full volume operation and continuoussmall improvements to achieve a balanced operation. The most appropriatemethod of process improvement is the Theory of Constraints (TO C) and notJlT.• The management must have a detailed, disciplined approach. This impliesstandardised methods of operation, and a high degree of training. Equally thereis the requirement for a special type of personnel to operate the cross dock.These operating personnel must be able to operate with precision (i.e. very lowerror rates) and be able to maintain this capability for continuous periods.• The systems required for a successful operation must include the capabilitiesof Yard Management, WMS for cross docking, Order Management withAdvanced Shipping Notice (ASN) capability and Track and Trace across thesupply chain. The items need to be identified by a barcode. The informationrequired on the barcode will be determined by. the information systemscapability of the least advanced service provider in the supply chain. If thisservice provider can receive and transmit all the data required for the supplychain from and to the other members, then the barcode need only be anidentification number of the specific item. The data pertaining to the items isthen passed from system to system in the supply chain. If data movement isnot possible between all the parties in the entire supply chain, then the barcodemust contain the information that will identify the item, the origin and the finaldelivery destination. If the items are delivered as part of a consignment, afurther quantum of information is required to identify the total number ofitems in the consignment and the specific item within the consignment.• The research shows that the overall capability of the cross dock or itsmaximum capacity is the combination of the capability of the personnel andthe cross dock design. Restrictions on either the personnel capability or thedesign of the cross dock, or both, severely reduces the effectiveness of thecross dock.• The previous research on the sequence of allocation of trucks to specific doorswithin the cross dock can be enhanced with a new sequencing method. Thenew method allocates the transport, in sequence of arrival, to the open doorthat either numrruses the walk distance in the facility; or maximises thecompletion of the consignments in order to minimise the area required to buildthe consignments; or a combination of both. The choice of these will bedetermined by the constraints imposed by the design of the building. This is animportant extension as this ties the supply chain into the cross dock operation,rather than looking at the cross dock in isolation as has been done in thisprevious research.• The factors that influence the design of a cross dock as to its size, shape,number of doors, and the specifically required additional areas, is defined indetail. The principles of these factors and their inter-relationships anddependencies are used in a detailed design for a cross dock. The detaileddesign process is set out from data analysis through to the actual sizecalculations and layouts. Measurements of walk distance and sort movementare used to determine the most effective design. The design is shown to beconsiderably more effective than the older designs.This work has significantly extended the research on the design principles and successfactors for implementation of cross docks in retail supply chains. The research derivesa unique new classification for cross docks. An improvement is made to existingresearch on the allocation of the transport to particular doors in the cross dock. Theoperation, management and personnel are shown to require specific characteristics.The information systems required for effective cross docks is determined and defined.The identification of the individual items by barcode and the information requiredwithin the barcode depending on the information sophistication of the serviceproviders in the supply chain is defined. A detail process to design a cross dock isevolved, with the full knowledge of the factors that must be considered and their interrelationships.Measurements to determine the effectiveness of the design are used tochoose the most appropriate design. All these are then synthesised into a new design,which is far more effective than any of the other designs researched. The designprocess will produce a very effective cross dock as has been demonstrated with a newfacility.

[发布机构] Stellenbosch University