Empty Container Repositioning Research Articles

Maritime Empty Container Repositioning

Maritime shipping containers are important to a number of different industries as they facilitate the reduction of transportation costs. To address the needs of shippers, empty containers need to be repositioned globally between seaports. Since the cost of empty container repositioning (ECR) constitutes a significant element of the total cost of running a global container fleet operation, the problem has been receiving increasing attention from scholars. The diversity of this literature necessitates the development an appropriate classification scheme to identify trends, gaps, and directions for future research. This paper reviews publications on maritime ECR over the last two decades and examines such trends and potential research directions.

A multi-scenario model for empty container repositioning with uncertain demand

This paper investigates the maritime repositioning of empty containers when their demand is uncertain. It involves moving empty containers from import-dominant ports to export-dominant ports in anticipation of future demands. In order to consider demand uncertainty, the problem is addressed by a stochastic programming approach, in which different scenarios are included in a multi-scenario optimisation model and explicitly linked by non-anticipativity conditions. Numerical experiments are carried out to show which benefits are obtained by multi-scenario solutions with respect to their deterministic counterparts, which consider only one point forecast for each uncertain parameter.

An optimization model for the inland repositioning of empty containers

The inland repositioning of empty containers is a crucial problem for shipping companies providing door-to-door transport services to customers. This activity consists of the allocation of heterogeneous fleets of empty containers between inland depots and ports, so that they can be properly positioned in anticipation of future customer requests. This paper describes how shipping companies perform this complex activity and its connections with truck routing problems and the repositioning of empty containers on maritime networks.To address the inland repositioning of empty containers, we propose a time-extended optimization model, whose innovative elements are decision variables and constrains on the so-called flexible leased containers, which can be on-hired and off-hired according to a number of clauses, and substitution options between container types. The experimentation shows that the model is an effective instrument to support the current decision-making process on this issue, because realistic size instances can be solved within time limits imposed by planning operations.

Long-haul liner service route design with ship deployment and empty container repositioning

This paper proposes a single liner long-haul service route design problem including route structure design, ship deployment and empty container repositioning. The objective of this problem is to minimise the total cost incurred from a liner long-haul service route, including ship related costs, fuel consumption costs, port related costs, laden containers and empty container inventory-in-transition costs. We propose a three-stage optimisation method to tackle the problem. We introduce the notions of topological structure and ship load factors, which lead to a classification of shipping route structures and the relationships between the container flow pattern and the route structure. This greatly simplifies the route structure design decisions at the first stage and enables us to develop an efficient heuristic algorithm to reposition empty containers at the second stage. The ship deployment problem concerning the number of ships and their capacity and sailing speeds is considered at the third stage. The model takes advantage of the characteristics of the existing route structures and can solve the service route design problems effectively from the practical perspective. In addition, the established relationships between the load factors and the route structure provide useful insights into ship utilisation and route structure choice. Case studies are presented to show efficiency and applicability of the proposed research methodology.

Maritime repositioning of empty containers under uncertain port disruptions

This paper addresses the problem of repositioning empty containers in maritime networks under possible port disruptions. Since drastically different futures may occur, the decision making process for dealing with this problem cannot ignore the uncertain nature of its parameters. In this paper, we consider the uncertainty of relevant problem data by a stochastic programming approach, in which different scenarios are included in a multi-scenario optimization model and linked by non-anticipativity conditions. Numerical experiments show that the multi-scenario solutions provide a hedge against uncertainty when compared to deterministic decisions and exhibit some forms of robustness, which mitigate the risks of not meeting empty container demand.

Incorporating Maritime Stakeholder Perspectives for Implementing an ‘Inland-Depots-for-Empty-Containers’ System Using an Analytic Hierarchy Process

Container movement involves several stakeholders where each group is focused on achieving its own objectives. By actively considering the perspective of different maritime stakeholders, this paper identifies a set of implementation strategies and prioritizes them to successfully implement an ‘Inland-Depots-for-Empty-Containers’ (IDEC) system in a region. It builds on the authors’ earlier work that developed and evaluated an IDEC system to minimize the overall system costs associated with regional repositioning of empty containers. Based on the benefits, costs and risks perceived by the involved maritime stakeholders on IDEC implementation, the authors identify strategies that may facilitate the building process and establish the system sustainably. They judge and prioritize the strategies in an Analytic Hierarchy Process (AHP) framework and present results based on their analysis. The authors believe that this research will benefit authorities considering an IDEC implementation strategy and also AHP practitioners.

Reducing hinterland transportation costs through container sharing

Based on two scenarios which describe the movement of full and empty containers within seaport hinterland transportation, this contribution determines possible benefits of exchanging empty containers between cooperating trucking companies. In the first scenario, trucking companies only have access to their own containers. In the second scenario, empty containers are permitted to be interchanged among several owners. Descriptions of both scenarios are given by comprehensive mathematical formulations considering vehicle routing, simultaneously with empty container repositioning. Realistic-sized instances are solved by applying an efficient tabu search heuristic. The results show that container sharing between trucking companies leads to remarkable cost savings.

The sample average approximation method for empty container repositioning with uncertainties

One of the challenges faced by liner operators today is to effectively operate empty containers in order to meet demand and to reduce inefficiency in an uncertain environment. To incorporate uncertainties in the operations model, we formulate a two-stage stochastic programming model with random demand, supply, ship weight capacity, and ship space capacity. The objective of this model is to minimize the expected operational cost for Empty Container Repositioning (ECR). To solve the stochastic programs with a prohibitively large number of scenarios, the Sample Average Approximation (SAA) method is applied to approximate the expected cost function. To solve the SAA problem, we consider applying the scenario aggregation by combining the approximate solution of the individual scenario problem. Two heuristic algorithms based on the progressive hedging strategy are applied to solve the SAA problem. Numerical experiments are provided to show the good performance of the scenario-based method for the ECR problem with uncertainties.

Stochastic Optimization of Empty Container Repositioning of Sea Carriage

To improve the efficiency of empty container repositioning for a shipping company, a stochastic optimization model of empty container repositioning of sea carriage was established by chance-constrained programming. The objective function was to minimize the cost of empty container repositioning including shipping, rening and shortage cost. In the model, shipping cost was decided by the number of ship used for empty container repositioning. The constraints of the model included meeting the need of empty containers, limit to the number of empty containers provided and the capacity of shipping. The numbers of empty containers required are stochastic. The stochastis model was transferred to an integer programming one. Lingo9.0 was used to solve the model and simulation was done under varied parameters to get a good shipping strategy. The results show that the model can provide an effective program of empty container repositioning for a shipping company and it is a good way to raise shipping efficiency.

Forecasting Empty Container Volumes

The accumulation and repositioning of empty containers have become acute problems for container ports and are expected to intensify in the future given the expected growth in trade imbalances among trading nations. These problems are major costs and operational challenges for container ports. More accurate forecasting of volumes of port empty containers will enable container ports to develop more cost efficient plans for the repositioning of empty containers. This paper compares the Tioga Group, United Nations and Winters method (utilizing empty container volumes of three U.S. container ports) in forecasting volumes of port empty containers. The Winters method is found to provide more accurate forecasts of volumes of port empty containers than the Tioga Group and United Nations methods.

글로벌 해운회사의 공컨테이너 재배치 최적화

H maritime company in Korea had a long history of difficulty in obtaining enough empty containers to transport its commodities. Despite efforts to resolve the problem, the repositioning of empty containers between depots was still planned manually, which consumed much worker time. To automate the generation of reposition plans, we developed a planning system to optimize the company's reposition of empty containers between global depots with a linear programming model functioning as a key decision engine in the system. The model determines the route, volume and mode of transportation for repositioning empty containers from depots with surplus containers to those requiring containers, as well as the empty space of ships generated from the unloading or loading of full and empty containers. The system has been in operation in the company's global network since March 2008.

A frequency-based maritime container assignment model

This paper transfers the classic frequency-based transit assignment method of Spiess and Florian to containers demonstrating its promise as the basis for a global maritime container assignment model. In this model, containers are carried by shipping lines operating strings (or port rotations) with given service frequencies. An origin–destination matrix of full containers is assigned to these strings to minimize sailing time plus container dwell time at the origin port and any intermediate transhipment ports. This necessitated two significant model extensions. The first involves the repositioning of empty containers so that a net outflow of full containers from any port is balanced by a net inflow of empty containers, and vice versa. As with full containers, empty containers are repositioned to minimize the sum of sailing and dwell time, with a facility to discount the dwell time of empty containers in recognition of the absence of inventory. The second involves the inclusion of an upper limit to the maximum number of container moves per unit time at any port. The dual variable for this constraint provides a shadow price, or surcharge, for loading or unloading a container at a congested port. Insight into the interpretation of the dual variables is given by proposition and proof. Model behaviour is illustrated by a simple numerical example. The paper concludes by considering the next steps toward realising a container assignment model that can, amongst other things, support the assessment of supply chain vulnerability to maritime disruptions.

Liner Shipping Cargo Allocation with Repositioning of Empty Containers

This paper is concerned with the cargo allocation problem considering empty repositioning of containers for a liner shipping company. The aim is to maximize the profit of transported cargo in a network, subject to the cost and availability of empty containers. The formulation is a multi-commodity flow problem with additional inter-balancing constraints to control repositioning of empty containers. In a study of the cost efficiency of the global container-shipping network, Song et al. (2005) estimate that empty repositioning cost constitutes 27% of the total world fleet running cost. An arc-flow formulation is decomposed using the Dantzig-Wolfe principle to a path-flow formulation. A linear relaxation is solved with a delayed column generation algorithm. A feasible integer solution is found by rounding the fractional solution and adjusting flow balance constraints with leased containers. Computational results are reported for seven instances based on real-life shipping networks. Solving the relaxed linear path-flow model with a column generation algorithm outperforms solving the relaxed linear arc-flow model with the CPLEX barrier solver even for very small instances. The proposed algorithm is able to solve instances with 234 ports, 16,278 demands over 9 time periods in 34 min. The integer solutions found by rounding down are computed in less than 5 s and the gap is within 0.01% from the upper bound of the linear relaxation. The solved instances are quite large compared to those tested in the reviewed literature.

Liner shipping service network design with empty container repositioning

This paper proposes a liner shipping service network design problem with combined hub-and-spoke and multi-port-calling operations and empty container repositioning. It first introduces a novel concept – segment – defined as a pair of ordered ports served by one shipping line and subsequently develops a mixed-integer linear programming model for the proposed problem. Extensive numerical experiments based on realistic Asia–Europe–Oceania shipping operations show that the proposed model can be efficiently solved by CPLEX for real-case problems. They also demonstrate the potential for large cost-savings over pure hub-and-spoke or pure multi-port-calling network, or network without considering empty container repositioning.

A Fluid Flow Model for Empty Container Repositioning Policy with a Single Port and Stochastic Demand

This paper is concerned with an optimal policy for empty container repositions. A single port is considered. The demand is modeled as a two-state Markov chain. The objective is to transport in and out containers so as to minimize the discounted holding, leasing, and repositioning costs. In this paper, the flow of containers is treated as though it is a continuous fluid. Dynamic programming is used to solve the optimal control problem. The associated HJB equations are used to characterize the value functions. The optimal policies are given in terms of threshold levels. Closed-form solutions of these threshold levels are obtained. Sufficient conditions are given in the form of a verification theorem. Numerical examples are reported to demonstrate the results.

Optimal slot allocation with empty container reposition problem for Asia ocean carriers

This paper utilises revenue management modelling to make an optimal slot allocation serving a specific shipping service route for ocean carriers. The model, incorporating the expected cost of empty container reposition, is formulated through mathematical programming to maximise operational profit of ocean carriers, subject to some constraints of vessel capacity, container demand and empty container supply. Computational results not only present port-to-port slot allocation to be a guideline to implement space control but also provide a criterion to review the status of strategic alliance among ocean carriers.

A reactive tabu search algorithm for the multi-depot container truck transportation problem

A container truck transportation problem that involves multiple depots with time windows at both origins and destinations, including the reposition of empty containers, is formulated as a multi-traveling salesman problem with time windows (m-TSPTW) with multiple depots. Since the problem is NP-hard, a cluster method and a reactive tabu search (RTS) algorithm are developed to solve the problem. The two methods are compared with the mixed integer program which can be used to find optimum solutions for small size problems. The computational results show that the developed methods, particularly the RTS algorithm, can be efficiently used to solve the problem.

Multi-port vs. Hub-and-Spoke port calls by containerships

This paper addresses the design of container liner shipping networks taking into consideration container management issues including empty container repositioning. We examine two typical service networks with different ship sizes: multi-port calling by conventional ship size and hub-and-spoke by mega-ship. The entire solution process is performed in two phases: the service network design and container distribution. A wide variety of numerical experiments are conducted for the Asia–Europe and Asia–North America trade lanes. In most scenarios the multi-port calling is superior in terms of total cost, while the hub-and-spoke is more advantageous in the European trade for a costly shipping company.

Empty container reposition planning for intra-Asia liner shipping

This paper addresses empty container reposition planning by plainly considering safety stock management and geographical regions. This plan could avoid drawback in practice which collects mass empty containers at a port then repositions most empty containers at a time. Empty containers occupy slots on vessel and the liner shipping company loses chance to yield freight revenue. The problem is drawn up as a two-stage problem. The upper problem is identified to estimate the empty container stock at each port and the lower problem models the empty container reposition planning with shipping service network as the Transportation Problem by Liner Problem. We looked at case studies of the Taiwan Liner Shipping Company to show the application of the proposed model. The results show the model provides optimization techniques to minimize cost of empty container reposition and to provide an evidence to adjust strategy of restructuring the shipping service network.

Regional Repositioning of Empty Containers

Regional repositioning of empty containers involves empty container movement between regional importers, marine terminals, depots, and export customers. This chain movement generates unproductive empty vehicle miles in the region. The problem of empty vehicle miles becomes more prominent because empty container depots are located close to the port and customers are inland. Considering the double-digit increase in containerized trade volumes and the persistent trade imbalance that strain existing depot capacities in major import areas, this paper focuses on the optimal location of new container depots and the repositioning of empty containers in a region. It proposes a system of inland depots for empty containers (IDEC) in which new depots would be built closer to customer clusters. An IDEC system can minimize the total system costs (cost of opening new depots plus repositioning cost of empties) and provide additional required capacity. The paper presents a mathematical model of such a system and discusses its feasibility and effectiveness. The proposed system is evaluated for a region based on the New York–New Jersey port region. Results show that by building inland depots, empty vehicle miles traveled and total system cost of repositioning empties are reduced significantly. At the same time, capacity is added to the system, preventing a shortfall that would result from the increase in trade and the trade imbalance. The authors believe that an IDEC system has great potential in optimizing regional empty moves.