A Review on Quantitative Approaches for Dock Door Assignment in Cross-Docking

Cross docking is a relatively new technique in supply chain operations. It offers limited storage time to maximize the efficiency of goods transshipment. Efficient operation of a cross docking system requires an appropriate coordination of inbound and outbound flows, accurate planning and dynamic scheduling.  The planning strategies at cross docking terminals, which are receiving growing attention today, are the truck-to-door assignment and destination to door assignment problems. This paper provides a comprehensive literature review of quantitative approaches in dock door assignment problems of cross docking planning. The contributions of this paper are to identify the gap of knowledge in operational levels mainly in dock door assignment and to point out the future research direction in cross docking

Dock Assignment and Truck Scheduling Problems at Cross-docking Terminals

In this paper, we consider the integration of dock assignment and truck scheduling problem at cross-docking terminals. The problem is first formulated as a 0-1 integer programming model. Since both dock assignment and truck scheduling problems are NP-hard, its integration is more difficult to solve. Thus we propose reduced variable neighborhood search (RVNS) algorithms to solve the problem. Computational experiments are carried out on four set of instances. The results show that RVNS is capable of finding good solutions in a much shorter computation time when it is compared with optimization solver Gurobi’s solutions

A Review: Mathematical Modles for Cross Docking Planning

This paper provides a comprehensive literature review of mathematical models in cross docking planning. From the reviews, the models are classified in three different levels regarding its decisions level which are operational, tactical, and strategic level. The researches in operational level are mainly related to develop model in scheduling, dock door assignment, transhipment problem, vehicle routing, and product allocation. For tactical and strategic level, the researches are mainly proposing model to design the layout and the network of cross docking respectively. The contribution of this paper is to realize the gaps of knowledge in strategic, tactical and operational levels and point out the future research directions in cross docking

An Ant Colony Optimization for the Multi-Dock Truck Scheduling Problem with Cross-Docking

Cross-docking operation is a new distribution strategy for synchronizing inbound and outbound trucks at the terminal. Products move directly from inbound dock to shipping dock without being stored in the distribution center. In this paper, we consider the truck scheduling problem which simultaneously determines dock assignment and truck scheduling of both inbound and outbound trucks for a multi-door cross-docking operation. The objective is to minimize total holding cost at the cross-docking terminal. A mixed integer programming model is first formulated for the problem. Since both dock assignment and truck scheduling problems are NP-hard, this truck scheduling problem is more difficult to solve. Thus we propose an ant colony optimization (ACO) algorithm for the problem. To evaluate the proposed ACO, 24 instances are generated and tested. The computational results and comparison with Gurobi optimizer solutions show that the ACO is competitive

越库转运问题的自适应遗传算法研究

探讨一种固定运输模式下的越库转运问题——采用运输量不可拆分的单次运送方式以最小费用通过选择固定的运输路径将货物经过越库转运到目的地,其货物将可能在越库中停留甚至无法运到目的地,这将会导致库存成本和惩罚成本.文中证明了此类越库转运问题是强NP难题,因此本文针对该问题的特殊结构,提出一种采用了邻域搜索技术的自适应遗传算法(AGA with NS)来有效的解决该类问题,数值试验结果表明该算法比CPLEX求解更加高效.此外文中还分别比较了在不采用邻域搜索或者自适应策略的情况下的三种遗传算法,其数值实验结果表明邻域搜索策略以及自适应策略对提高算法的效率有显著的影响

Application of Tabu Search to Scheduling Trucks in Multiple Doors Cross-Docking Systems

RÉSUMÉ : Cette recherche focus sur l’amélioration des cross-dockings en vue d’augmenter les niveaux de performance du service et de réduire les coûts. l’algorithme de la recherche avec tabous est étudiée pour trouver la séquence optimale d’entrée et sortie des remorques au cross-docking. L’objectif de cette recherche est de maximiser le nombre total de transferts directs entre le fournisseur et une destination finale commune de livraison. Dans les stratégies de distribution actuelles, l’objectif est de synchroniser les chaines du fabricant et du client. Le cross-docking implique de recevoir les produits d’un fournisseur pour plusieurs clients et d’occasionnellement consolider cela avec les produits d’autres fournisseurs pour des destinations finales de livraison communes. En résumé, l’approche examinée dans cette recherche donne une occasion significative pour l’amélioration des opérations au Cross-docking par la réduction du stockage des produits.----------ABSTRACT : Today’s supply chain management performance has been affected by continuously increasing pressure of market forces. The pressure of market includes demands on increased flow of products and throughput with less amount of storage, also customers demand for more products with lower operational costs and more value-added services provided to customers. Supply chain is responsible in cost reduction and service levels increase by providing transshipments across its members. However supply chain has to face fluctuations of demands with the short available lead times. Physical problem of warehouse limitations and also inventory costs and shipping affect the performance of supply chain. In today’s distribution strategies, the main goal is to provide a synchronization of customer chains and the suppliers. The objective is to reduce the inventory buffering between customers and suppliers. The idea of cross-docking is to receive different goods from a manufacturer for several end destinations and possibly consolidate the goods with other manufacturer’s items for common final customers; then ship them in the earliest possible time. The focus of this research effort is to improve cross-dock operations with the goal of increasing the service performance levels and reducing costs. Specifically, metaheuristics algorithm of Tabu search is investigated for finding optimal sequence of incoming and outgoing trailers at cross-docks. This thesis reviews available research literature on cross-dock operations. Tabu search for the truck scheduling problem is presented along with results. Tabu search algorithm is investigated for the truck scheduling problem in the multiple doors cross-docking with unknown incoming and outgoing sequences. The objective of this research is to maximize the total direct transfer of products from a supplier to common final delivery destinations. The algorithm is implemented in C++ and analyzed using different problem instances. The results gained from algorithm of Tabu search are compared with other iterative heuristic descent method. The results indicate that the Tabu search performs significantly better than the descent method for large problem instances. In general, the results present that a metaheuristic algorithm of Tabu search for multiple or single door cross-docking offers thelargest potential for improvement. In summary, the approach explored in this research offers significant opportunity to improve cross-dock operations through reducing storage of products

Ordonnancement de camions dans une plateforme logistique : complexité, méthodes de résolution et incertitudes

La problématique dite de crossdocking a été source de beaucoup d'attention ces dernières années dans la littérature. Un crossdock est une plateforme logistique favorisant, par une synchronisation efficace des camions entrants et sortants, une rotation rapide des produits, le volume de produits stockés devant être le plus faible possible. Le crossdocking soulève de nombreux problèmes logistiques, dont notamment celui de l'ordonnancement des camions entrants et sortants sur les quais de la plateforme. L'objectif classiquement considéré dans la littérature pour ce problème est la minimisation du makespan, critère très répandu en d'ordonnancement. Pour le crossdocking néanmoins, minimiser la date de départ du dernier camion ne garantie pas nécessairement une bonne synchronisation des camions et le makespan ne semble donc pas être l'objectif le plus pertinent. Pour répondre au besoin de synchronisation et favoriser les rotations rapides, notre travail propose alternativement de minimiser la somme des temps de séjour des palettes dans le stock. Nous étudions d'abord la version déterministe de ce problème d'ordonnancement. Sa complexité est détaillée selon différentes hypothèses pour identifier les éléments menant à sa NP-difficulté. Différentes méthodes de résolutions sont proposées. Une méthode classique de programmation linéaire en nombres entiers utilisant des variables de décision indexées par le temps. Une famille d'inégalités valides est également proposée et exploitée dans un algorithme avec ajout itératif de coupes. Des méthodes basées sur la programmation par contraintes sont enfin proposées. Une analyse comparative de ces différentes méthodes est proposée. Dans un deuxième temps, nous étudions une version non-déterministe de notre problème d'ordonnancement dans laquelle des incertitudes sur les dates d'arrivée des camions sont introduites sous la forme d'intervalles de temps équiprobables. Une méthode d'ordonnancement proactive-réactive utilisant le concept de groupes d'opérations permutables est proposée pour faire face aux incertitudes. Des groupes de camions permutables sont séquencés et affectés aux quais puis, durant l'exécution d'ordonnancement, en fonction de la réalisation des dates d'arrivée, un ordre est choisi dans chaque groupe à l'aide d'un algorithme réactif.Crossdocking has received a lot of attention in the literature in recent years. A crossdock is a logistic platform that promotes rapid product turnover through efficient synchronization of incoming and outgoing trucks, with the volume of products stored being kept as low as possible. Crossdocking raises many logistical problems, including the scheduling of incoming and outgoing trucks on the platform's docks. The classical objective considered in the literature for this problem is the minimization of the makespan, a very common criterion in scheduling. However, for crossdocking, minimizing the departure date of the last truck does not necessarily guarantee a good synchronization of the trucks and the makespan does not seem to be the most relevant objective. In order to meet the need for synchronization and to help fast rotations, our work proposes alternatively to minimize the sum of the pallets' sojourn times in the warehouse. We first study the deterministic version of this scheduling problem. Its complexity is detailed under different assumptions to identify the elements leading to its NP-hardness. Different solution methods are proposed. A classical integer linear programming method using time-indexed decision variables. A family of valid inequalities is also proposed and exploited in an algorithm with iterative addition of cuts. Finally, methods based on constraint programming are proposed. A comparative analysis of these different methods is proposed. In a second step, we study a non-deterministic version of our scheduling problem in which uncertainties on truck arrival dates are introduced in the form of equiprobable time intervals. A proactive-reactive scheduling method using the concept of permutable operation groups is proposed to cope with the uncertainties. Groups of permutable trucks are sequenced and assigned to the docks and then, during the scheduling run, based on the realization of arrival dates, an order is chosen in each group using a reactive algorithm

Diseño y desarrollo del modelo óptimo de asignación y cronograma de remolques en el sistema de cadena de suministro con consideración de cross dock con planificación estocástica

Todays, transportation, and logistics engineering processes are among the important issues of organizations in the competitive market. Considering the logistical structure of the logistics engineering and the more attention paid to the logistical tools and, in particular, such as the use of these tools, such as containers (pallets, containers, etc.), transportation equipment (trailer, forklift trucks, etc.), and The art of building the supply and distribution network concerning the main warehouses, cross-dock, and temporary storage, is one of the most critical and contemplative cases. In fact, all these tools work together to maximize system efficiency in the field of logistics concerning the leading impact indicators, including the time of shipment (loading, disloading, the allocation of trailers, etc.). This paper's main goal is to present and develop a mathematical model of trailer schedule planning in possible conditions in the cross-dock. In fact, the main function of this mathematical model is to minimize the total time of the logistics process from the stage of emptying the pallets from the materials producers in the cross docks and assigning the trailer to the door, and finally reloading the pallets to be distributed to the production sites. To solve this model and to analyze the outputs, mixed integer programming was used by GAMS software.Hoy en día, los procesos de ingeniería de transporte y logística se encuentran entre los temas importantes de las organizaciones en el mercado competitivo. Teniendo en cuenta la estructura logística de la ingeniería logística y la mayor atención prestada a las herramientas logísticas y, en particular, como el uso de estas herramientas, como contenedores (pallets, contenedores, etc.), equipos de transporte (remolque, carretillas elevadoras, etc.), y El arte de construir la red de suministro y distribución con respecto a los almacenes principales, cross dock y almacenamiento temporal, es uno de los casos más importantes y contemplativos. De hecho, todas estas herramientas trabajan juntas para maximizar la eficiencia del sistema en el campo de la logística con respecto a los principales indicadores de impacto, incluido el tiempo de envío (carga, descarga, asignación de remolques, etc.). El objetivo principal de este artículo es presentar y desarrollar un modelo matemático de planificación de horarios de remolques en las posibles condiciones en el muelle de cruce. De hecho, la función principal de este modelo matemático es minimizar el tiempo total del proceso logístico desde la etapa de vaciado de los pallets de los productores de materiales en los cross docks y la asignación del remolque a la puerta y finalmente la recarga de los pallets a distribuir. a los sitios de producción. Para resolver este modelo y analizar las salidas, el software GAMS utilizó la programación de enteros mixtos

Cross-dock Scheduling with Known Shipment Unloading Order

Cross-docking is a logistics strategy which is widely used these days in different industries. Cross-docking takes place in a distribution docking centre and consists of trucks and dock doors on inbound and outbound sides.Products from suppliers get unloaded at inbound doors from incoming trucks, consolidated, transferred and loaded into outgoing trucks at outbound doors, with little or no storing them in between. We study two scenarios of cross-docking scheduling problem: scheduling inbound side with fixed outbound side scheduling and scheduling both inbound and outbound sides. In the former scenario, we introduce five mixed integer programming models with enhanced pre-processing and extensions to minimize the total number of tardy products. In the later scenario, we proposed new linear mixed integer programming models where transportation time between dock doors are considered. The objective in the second case is to minimize the maximum lateness of outgoing trucks. In both scenarios, we integrate the unloading order of shipments in incoming trucks into our models. Computational results show that taking advantage of that information helps improving the truck scheduling and assessing much more accurately the number of tardy products and lateness