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

Vehicle routing problem with cross-docking as part of industry 4.0 logistics

The work presented in this paper has been supported by West Bohemia University in Pilsen (project No.SGS SGS-2021-022 - Financial (stock) markets, modeling and prediction of behavior).The trends associated with the onset of Industry 4.0 are obvious and require a prompt response from the company. An indisputable advantage is the use of the cross-docking strategy, which makes it possible to coordinate all logistics processes and achieve optimization of transport costs while maintaining minimal handling and storage. The goods are directly redistributed within the distribution system to specific customers according to their requirements without the need for storage. This logistic method is very often associated with various types of vehicle routing problem. It enables the introduction and use of Industry 4.0 principles. The aim of this contribution is to find out the possibilities of using Cross-docking within the vehicle routing problem. The output is a classification of five vehicle routing problems and their further breakdown, which are successfully connected with the idea of Cross-docking technology. This is a Capacitated vehicle routing problem with cross-docking, Open vehicle routing problem with cross-docking, Vehicle routing problem with cross-docking for multi-products, Multi-echelon distribution networks and Rich vehicle routing problem with cross-docking. Literature analysis shows that it is not an isolated technology but a tool offering a comprehensive logistics service connecting several processes. Offer various combinations of technologies in conjunction with vehicle routing problems to provide economic benefit and reduce the environmental impact of logistics chains

The multi-vehicle dial-a-ride problem with interchange and perceived passenger travel times

The Dial-a-Ride Problem (DARP) introduced in the early 1980s is the NP-Hard optimization problem of developing the most cost-efficient vehicle schedules for a number of available vehicles that have to start from a depot, pick up and deliver a set of passengers, and return back to the same depot. DARP has been used in many modern applications, including the scheduling of demand-responsive transit and car pooling. This study departs from the original definition of DARP and it extends it by considering an interchange point where vehicles can exchange their picked-up passengers with other vehicles in order to shorten their delivery routes and reduce their running times. In addition to that, this study introduces the concept of generalized passenger travel times in the DARP formulation which translates the increased in-vehicle crowdedness to increased perceived passenger travel times. This addresses a key issue because the perceived in-vehicle travel times of passengers might increase when the vehicle becomes more crowded (i.e., passengers might feel that their travel time is higher when they are not able to find a seat or they are too close to each other increasing the risk of virus transmission or accidents). Given these considerations, this study introduces the Dial-a-Ride Problem with interchange and perceived travel times (DARPi) and models it as a nonlinear programming problem. DARPi is then reformulated to a MILP with the use of linearizations and its search space is tightened with the addition of valid inequalities that are employed when solving the problem to global optimality with Branch-and-Cut. For large problem instances, this study introduces a tabu search-based metaheuristic and performs experiments in benchmark instances used in past literature demonstrating the computation times and solution stability of our approach. The effect of the perceived passenger travel times to the vehicle running costs is also explored in extensive numerical experiments.</p

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

Horizontale en verticale samenwerking in distributieketens met cross-docks

Logistiek dienstverleners staan voor grote uitdagingen op het gebied van duurzaamheid, in het bijzonder vanwege de steeds kleiner wordende zendingen die just-in-time bij de klant moeten worden afgeleverd. Samenwerking tussen partners in de distributieketen en met concurrenten daarbuiten biedt kansen om deze uitdagingen het hoofd te bieden. Dit proefschrift richt zich op samenwerkingsvormen in distributieketens met cross-docks. Cross-docks zijn logistieke centra die bedrijven in staat stellen om kleine zendingen gegroepeerd te transporteren zonder dat daarvoor tussentijdse opslag nodig is. In een cross-dock worden goederen direct van inkomende naar uitgaande vrachtwagens verplaatst. Het succesvol toepassen van cross-docking vereist verticale samenwerking tussen partners in opeenvolgende stadia van de distributieketen. Horizontale samenwerking ontstaat tussen mogelijk concurrerende bedrijven die vergelijkbare activiteiten in verschillende distributieketens uitvoeren. Dit proefschrift presenteert theoretische modellen voor horizontale en verticale samenwerking in distributieketens met cross-docks en bestudeert oplossingsmethodieken waarmee de duurzaamheid van deze ketens kan worden verbeterd. Daarvoor worden concepten uit de vakgebieden informatiesystemen, Operations Research en Supply Chain Management gecombineerd. De in dit proefschrift beschreven classificatie van wiskundige cross-docking modellen onthult nieuwe onderzoeksvragen gericht op een betere afstemming tussen interne cross-dock processen en ketenlogistiek. Een simulatiestudie illustreert hoe geringe aanpassingen in de ketenlogistiek tot grote prestatieverbeteringen in het cross-dock leiden. Op het gebied van horizontale samenwerking is een methode ontwikkeld die de uitwisseling van ladingen tussen transporteurs systematiseerd. Een reeks casussen toont aan dat doorbraken in ICT ontwikkeling nodig zijn om samenwerkende transporteurs in staat te stellen gezamenlijk planningsbeslissingen te nemen