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

Cross-docking: A systematic literature review

This paper identifies the major research concepts, techniques, and models covered in the cross-docking literature. A systematic literature review is conducted using the BibExcel bibliometric analysis and Gephi network analysis tools. A research focus parallelship network (RFPN) analysis and keyword co-occurrence network (KCON) analysis are used to identify the primary research themes. The RFPN results suggest that vehicle routing, inventory control, scheduling, warehousing, and distribution are most studied. Of the optimization and simulation techniques applied in cross-docking, linear and integer programming has received much attention. The paper informs researchers interested in investigating cross-docking through an integrated perspective of the research gaps in this domain. This paper systematically reviews the literature on cross-docking, identifies the major research areas, and provides a survey of the techniques and models adopted by researchers in the areas related to cross-docking

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

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

Scheduling Material Handling in Cross-Docking Terminals

RÉSUMÉ : La manutention au sein des plateformes de distribution est un problème d’ordonnancement. Le transport interne des produits doit en effet être synchronisé avec les arrivées et les départs des camions. Ce problème se retrouve dans toutes les plateformes de distribution où la manipulation des produits est effectuée manuellement par l’opérateur. Dans cette thèse, nous investiguons ce problème d’ordonnancement dans les plateformes de distribution. Nous mettons en relief les différentes facettes de ce problème et proposons une classification de ses différents sous problèmes. De manière générale, l'objectif est d'éviter les doubles manipulations (déplacer un produit d’un camion vers le stock, puis du stock vers un camion) qui doublent les coûts sans valeur ajoutée. Il faut minimiser ces doubles manipulations en orchestrant les transferts internes et la séquence de chargement/ déchargement des camions. Dans une première partie, nous analysons la structure du problème avec un modèle simplifié n’ayant qu’un quai de réception et un quai d’envois. Nous formalisons les décisions de manipulation interne et développons un algorithme optimal pour déterminer le meilleur plan de transfert de produits lorsque la séquence des camions est connue. Cet algorithme est utilisé comme fonction d’évaluation dans une recherche stochastique pour minimiser les doubles manipulations et optimisant les séquences de chargement/déchargement. Nous présentons ensuite un modèle de programmation linéaire en nombres entiers du problème général (ordonnancement des arrivées et départs de camions et transfert interne des produits). Nous proposons un algorithme de séparation et d’évaluation permettant une résolution efficace du problème. Nous proposons des structures de dominance et quelques inégalités valides permettant d’améliorer les performances de l’algorithme. Cette approche nous permet de résoudre à l’optimum en un temps raisonnable de très gros problèmes. Dans une seconde partie, nous étendons ces modèles au problème général avec plusieurs quais. Nous nous intéressons d’abord au terminal de type satellite où l’ordonnancement des camions d’entrée est connu. Ces plateformes opèrent en deux mouvements différents : l’ordonnancement et chargement pour le transport de nuit et celui pour les livraisons matinales. Nous donnons une représentation mathématique qui permet de résoudre les problèmes de petite taille. Pour ceux de plus grandes ampleurs, nous utilisons une heuristique. Les résultats numériques montrent la validité de cette approche. Finalement, nous généralisons le type de plateforme (les séquences d’arrivée et de départ sont à déterminer) et développons un nouveau modèle d’ordonnancement plus compact. Nous utilisons pour les grandes instances une recherche par voisinage. Nous mettons en place des voisinages originaux adaptés à ce type d’ordonnancement. Mots clés: Transfert de produits, ordonnancement, plateforme de transbordement, recherche stochastique, programmation à nombres entiers, heuristiques, recherche du plus proche voisin.----------ABSTRACT : Material handling in cross-dock is a relevant class of scheduling problems in distribution centers in which inner transhipment decisions need to be considered in addition to the processing order of trucks. The problem has applications in distribution centers where operators manually perform internal transhipment. In this dissertation, we investigate the problem of material handling inside cross-docking terminals. The main component of the problem is presented, followed by a classification scheme to express its diversity. Moreover, double handling identifies the main source of deficiencies in transferring operations. The objective is to synchronize the trucks’ loading and unloading sequences with internal transferring decisions to minimize excessive product displacement inside the terminal. First, the problem is studied for a conceptual model of the platform with single receiving and shipping doors. We formalize decisions on internal transhipment and develop an algorithm to determine the best transferring plan with restricted orders on processing trucks. This algorithm is employed as an evaluation function in a stochastic search framework to ameliorate the order of processing trucks and reduce the cost of double handling. Then, a mixed integer linear programming formulation of the general problem is introduced. The proposed model determines the joint schedule between processing order of trucks at inbound and outbound doors with an internal transhipment plan. A path branching algorithm is proposed. We present several structural properties and some valid inequalities to enhance the performance of the algorithm. This method could solve fairly large instances within a reasonable time. Second, we extend the developed models and approaches to schedule material handling process for a real platform with multiple doors. In the first installment, we focus on the satellite cross-docks that have limitations on the processing order of trucks at inbound door. These platforms operate in two separate shifts: consolidating pickup freight for overnight shipments and processing received products for early morning deliveries. A mathematical formulation of the problem is presented that can solve small instances with commercial software. In addition, a sequential priority-based heuristic is introduced to tackle the large problems. Numerical results depict the stability of this approach. Finally, in the second instalment, we study the general model with no restriction on the arrival and departure pattern of trucks and formulate a new mathematical model. This model has considerably fewer variables and constraints than the previous one. Moreover, a variable neighborhood search heuristic is developed to tackle real life problems. This method consists of several operators incorporated in a search subroutine to find local optima and a perturbation operator to alter it. The developed method is adopted for three scenarios concerning limitations imposed by the network schedule. The analyzes demonstrate economical savings in the cost of material handling. Keywords: Material handling; scheduling; cross-dock; stochastic search; Integer programming; heuristic; variable neighborhood search

Models and Algorithms for Inbound and Outbound Truck to Door Scheduling

Cross-docking is a logistic strategy that facilitates rapid movement of consolidated products between suppliers and retailers within a supply chain. It is also a warehousing strategy that aims at reducing or eliminating storage and order picking, two of which are known to be major costly operations of any typical warehouse. This strategy has been used in the retailing, manufacturing, and automotive industries. In a cross-dock, goods are unloaded from incoming trucks, consolidated according to their destinations, and then, loaded into outgoing trucks with little or no storage in between. In this thesis, we address an integrated cross-dock door assignment and truck scheduling problem in which the assignment and sequencing of incoming trucks to strip doors and outgoing trucks to stack doors is optimized to minimize the total time to process all trucks. We present a mixed integer programming formulation to model this problem and some valid inequalities to strengthen the formulation. We also present two metaheuristics to obtain high quality solutions in reasonable CPU times. These algorithms use a mix of composite dispatching rules, constructive heuristics, local search heuristics which are embedded into a greedy randomized adaptive search procedure (GRASP) and an iterated local search (ILS). Results of computational experiments are presented to assess the performance of the proposed algorithms, in comparison with a general purpose solver

Design and Analysis of Efficient Freight Transportation Networks in a Collaborative Logistics Environment

The increase in total freight volumes, reducing volume per freight unit, and delivery deadlines have increased the burden on freight transportation systems of today. With the evolution of freight demand trends, there also needs to be an evolution in the freight distribution processes. Today\u27s freight transportation processes have a lot of inefficiencies that could be streamlined, thus preventing concerns like increased operational costs, road congestion, and environmental degradation. Collaborative logistics is one of the approaches where supply chain partners collaborate horizontally or/and vertically to create a centralized network that is more efficient and serves towards a common goal or objective. In this dissertation, we study intermodal transportation, and cross-docking, two major pillars of efficient, cheap, and faster freight transportation in a collaborative environment. We design an intermodal network from a centralized network perspective where all the participants intermodal operators, shippers, carriers, and customers strive towards a synchronized and cost-efficient freight network. Also, a cross-dock scheduling problem is presented for competitive shippers using a centralized cross-dock facility. The problem develops a fast heuristic and meta-heuristic approach to solve large-scale real-world problems and draws key insights from a cross-dock operator and inbound carrier\u27s perspectives