Handling disruptions in a network with cross-docking

Cross-docking (CD) is a commonly used technique to consolidate freight for more efficient delivery to customers; CD is continuing to see increased use by companies. Synchronization of inbound and outbound freight is clearly critical to operations and so is having the cross-dock able to support the freight flow with available doors and material handling equipment. The latter is particularly important when there is a disruption in the inbound freight. One delayed truck can impact several outbound trucks. A methodology is proposed to address explicitly both the scheduling of trucks and material handling within the CD. Two models are proposed – one for routing inbound and outbound trucks and the other to schedule the cross-dock. Results from each model when run separately are presented as well as results from when the two models are run iteratively

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

The parcel hub scheduling problem with limited conveyor capacity and controllable unloading speeds

We investigate a specific truck scheduling problem at cross-docks in the postal service industry on an operational level aiming to maximise the number of duly parcels assuming fixed departure times of the outbound trucks. The inbound gates and the conveyors as means of transportation inside the hub constitute the bottleneck resources. As a novel extension, we propose flexible unloading speeds to efficiently utilise the scarce resources. We formalise the problem with a mixed integer program and explicitly incorporate controllable unloading speeds of the inbound trucks. We determine the computational complexity and develop a genetic algorithm to efficiently solve the problem. Our investigation focuses on both the performance of the genetic algorithm and the applicability of the results in a real-world environment by implementing scheduling policies in a simulation model that considers individual parcel interactions. Based on our experimental results, we can state that especially in problem settings with scarce conveyor capacities, our approach to incorporate controllable unloading speeds has the potential of significantly increasing the number of duly parcels

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

Cross-Docking: A Proven LTL Technique to Help Suppliers Minimize Products\u27 Unit Costs Delivered to the Final Customers

This study aims at proposing a decision-support tool to reduce the total supply chain costs (TSCC) consisting of two separate and independent objective functions including total transportation costs (TTC) and total cross-docking operating cost (TCDC). The full-truckload (FT) transportation mode is assumed to handle supplier→customer product transportation; otherwise, a cross-docking terminal as an intermediate transshipment node is hired to handle the less-than-truckload (LTL) product transportation between the suppliers and customers. TTC model helps minimize the total transportation costs by maximization of the number of FT transportation and reduction of the total number of LTL. TCDC model tries to minimize total operating costs within a cross-docking terminal. Both sub-objective functions are formulated as binary mathematical programming models. The first objective function is a binary-linear programming model, and the second one is a binary-quadratic assignment problem (QAP) model. QAP is an NP-hard problem, and therefore, besides a complement enumeration method using ILOG CPLEX software, the Tabu search (TS) algorithm with four diversification methods is employed to solve larger size problems. The efficiency of the model is examined from two perspectives by comparing the output of two scenarios including; i.e., 1) when cross-docking is included in the supply chain and 2) when it is excluded. The first perspective is to compare the two scenarios’ outcomes from the total supply chain costs standpoint, and the second perspective is the comparison of the scenarios’ outcomes from the total supply chain costs standpoint. By addressing a numerical example, the results confirm that the present of cross-docking within a supply chain can significantly reduce total supply chain costs and total transportation costs

Cross-docking with vehicle routing problem. A state of art review 1

Este artículo presenta una revisión al estado del arte durante los últimos diez años, de la literatura relacionada con las plataformas de intercambio logísticas, denominadas Cross-Docking. Este tipo de sistemas surgen como alternativa para reducir el costo logístico y el tiempo de respuesta al cliente. El objetivo consiste en simplificar algunos procesos tales como almacenamiento y manejo de materiales, a partir de la reducción de períodos de bodegaje y realización de surtida de materiales en los muelles de ingreso y salida de mercancía. En la primera parte, se desarrolla el concepto, su funcionamiento operativo y clasificación. En la segunda parte, se realiza un reporte de los trabajos más relevantes acerca de esta técnica. Posteriormente, se profundiza en este tema y el ruteo de vehículos simultáneos, haciendo énfasis en los métodos de solución, puesto que se trata de un problema de optimización combinatoria, clasificado como de alta complejidad computacional. Al final, se presentan conclusiones y la discusión.This article reviews the state of the art for the last ten years about the literature related to Cross-Docking. The Cross-Docking systems emerge as an alternative to reduce logistics costs and customer response time in some processes such as warehousing and material handling, times by reducing storage and picking, on the docks of inbound and outbound of vehicles. In the first part, the concept of Cross-Docking is developed, also its operating performance and classification. In the second part, a report on the most relevant works is done. Subsequently, it delves into the issue of vehicle routing and Cross-Docking with emphasis on methods of solution, since it is a combinatorial optimization problem classified as NP-hard. The document ends with the conclusions and discussion

Multi-criteria Analysis of Internal Cross-docking Operations

RÉSUMÉ : Cette étude vise à améliorer la performance environnementale et logistique des opérations de manutention dans un centre de transbordement (soit cross-dock). L’évaluation des opérations internes considère ainsi plusieurs mesures de performance, d’où s’explique la désignation multicritère. L’installation étudiée appartient à une organisation qui fournit des services de transport en charge partielle (LTL), desservant un vaste réseau d’approvisionnement. À l’intérieur du centre de transbordement, toute la manutention est accomplie par des caristes en utilisant des chariots élévateurs à gaz naturel comprimé (GNC). Premièrement, une revue de littérature a été complétée dans l’intention de déterminer une façon systématique de caractériser et d’étudier des centres de transbordement. En conséquence, une grille de caractérisation fondée sur six critères a été développée pour décrire qualitativement une installation de transbordement. Quoi que la plupart des études en transbordement optent pour des modèles de recherche opérationnelle, la recherche scientifique propose que les modèles de simulation à évènements discrets soient aussi des outils appropriés et propices pour l’analyse de ce type d’installation - malgré leur faible popularité dans le domaine. À la suite de ces repères, un modèle de simulation par agents a été développé pour cette étude, inspiré par des modèles existants d’entreposage, ainsi que par des techniques de modélisation traditionnelles adaptées au milieu industriel. Également, une analyse de l’état initial des opérations de transbordement fut complétée avec l’intention de définir les limites du modèle, ses entrants et les interactions entre ses agents. Finalement, une validation statistique du modèle de simulation fut effectuée afin de déterminer le nombre approprié de réplications. Ensuite, le modèle final fut utilisé pour l’expérimentation des différentes stratégies d’affectation des portes du centre de transbordement. Ces expériences avaient deux variables de réponse : la consommation de GNC (en mètres cubiques) et la distance couverte par la flotte de chariots élévateurs (en pieds). De plus, les émissions équivalentes de CO2 furent aussi calculées (en kilogrammes équivalents de CO2). Quant aux facteurs expérimentaux, les expériences se basent sur des variations dans l’affectation des portes de l’installation aux activités de manutention (chargement, déchargement) et aux zones de distribution. Dans d’autres termes, chaque expérience est axée sur une combinaison unique d’affectation des portes, désignée comme solution d’affectation. Puisqu’une quantité incommensurable de solutions sont possibles, une heuristique fut créée dans le but de générer des solutions d’affection d’après la distance minimale entre les portes et les flots de palettes par zones d’origine et de destination. En outre, des affectations aléatoires et un scénario sans aucune affectation furent aussi considérés. Les résultats expérimentaux confirment que des changements dans l’affectation de portes peuvent réduire la consommation totale de combustible et les déplacements des appareils de manutention, ainsi que les émissions de CO2. En outre, cette étude met en évidence que l’empreinte environnementale des installations de distribution n’est point négligeable. L’approche multicritère et notamment la perspective environnementale deviennent ainsi pertinentes aux études en logistique interne. Or, une recherche plus approfondie serait nécessaire afin d’évaluer l’impact de l’affectation de portes dans tout le système de transbordement, au-delà des murs de l’installation. Sommaire des résultats Distance (ft) GNC (m3) CO2 (kg éq.) Scénario sans aucune affectation 531 663 745 1 432 Performance initiale 514 656 702 1 349 Meilleure solution d’affectation 489 673 626 1 203 ----------ABSTRACT : The performance of internal material handling operations in an existing cross-docking facility is sought to be improved from both a logistic and environmental perspective. The facility studied consists of a transportation terminal serving a vast less-than-truckload (LTL) chain. Inside the cross-dock, all material handling is performed by forklifts fuelled by compressed natural gas (CNG). A review of the state of the art is conducted, from which a cross-dock characterization approach is outlined. Similarly, the literature reveals that discrete-event simulation, while generally under-looked, is an appropriate tool for the study of such transportation facilities. Accordingly, an agent-based simulation (ABM) model is developed in order to study the cross-dock. The model is influenced by existing warehousing models, as well as by traditional discrete-event modelling in an industrial setting. Moreover, a comprehensive analysis of the current state of operations was completed in order to define model boundaries, inputs and agent interactions. Then, the model was used to conduct experiments based on distinct door-assignment strategies, having CNG consumption and forklift distance as response variables. The generation of door assignments, conversely, was achieved by a heuristic based on the minimum distance between dock doors and pallet flow. The experimental results indicate that such door assignments do lead to a reduction in both response variables. Further study is, howbeit, required to assess the full impact of door assignments in the system, beyond internal boundaries

Smart Industry - Better Management

The ebook edition of this title is Open Access and freely available to read online. Smart industry requires better management. As industrial and production systems are future-proofed, becoming smart and interconnected through use of new manufacturing and product technologies, work is advancing on improving product needs, volume, timing, resource efficiency, and cost, optimally using supply chains. Presenting innovative, evidence-based, and cutting-edge case studies, with new conceptualizations and viewpoints on management, Smart Industry, Better Management explores concepts in product systems, use of cyber physical systems, digitization, interconnectivity, and new manufacturing and product technologies. Contributions to this volume highlight the high degree of flexibility in people management, production, including product needs, volume, timing, resource efficiency and cost in being able to finely adjust to customer needs and make full use of supply chains for value creation. Smart Industry, Better Management illustrates how industry can enabled by a more network-centric approach, making use of the value of information and the latest available proven manufacturing techniques

Cargo Logistics Airlift Systems Study (CLASS). Volume 1: Analysis of current air cargo system

The material presented in this volume is classified into the following sections; (1) analysis of current routes; (2) air eligibility criteria; (3) current direct support infrastructure; (4) comparative mode analysis; (5) political and economic factors; and (6) future potential market areas. An effort was made to keep the observations and findings relating to the current systems as objective as possible in order not to bias the analysis of future air cargo operations reported in Volume 3 of the CLASS final report