Análisis de políticas enfocadas a la reducción de costos asociados al flujo de contenedores para carga seca, aplicado a una línea naviera en Colombia

154 páginasLa toma de decisiones frente a la planeación, diseño y operación de actividades para una Línea Naviera especializada en carga en contenedores es una tarea compleja en cuanto a la gestión sobre los flujos de contenedores se refiere. Algunos modelos han sido desarrollados con el fin de mejorar el desempeño en el manejo de los flujos de contenedores, sin embargo es preciso diseñar modelos específicos para trabajar problemáticas puntuales. Este proyecto comprende la descripción del problema asociado al manejo de contenedores por parte de una Línea Naviera en Colombia, la construcción y validación de un modelo empleando dinámica de sistemas, y la evaluación del impacto de políticas frente a distintos escenarios con el fin de analizar el posible desempeño de la gestión de costos y nivel de servicio

Tank container operators’ profit maximization through dynamic operations planning integrated with the quotation-booking process under multiple uncertainties

Tank Container Operators (TCOs) are striving to maximize profit through the integration of their global Tank Container (TC) operations with the job quotation-booking process. However, TCOs face a set of unique challenges not faced by general shipping container operators, including the process uncertainties arising from TC cleaning and the use of Freight Forwarders (FFs). In this paper, a simulation-based two-stage optimization model is developed to address these challenges. The first stage focuses on tactical decisions of setting inventory levels and control policy for empty container repositioning. The second stage integrates the dynamic job acceptance/rejection decisions in the quotation-booking processes with container operations decisions in the planning and execution processes, such as job fulfilment, container leasing terms, choice of FFs considering cost and reliability, and empty tank container repositioning. The solution procedure is based on the simulation model combined with heuristic algorithms including an adjusted Genetic Algorithm, mathematical programming, and heuristic rules. Numerical examples based on a real case study are provided to illustrate the effectiveness of the model.Tank Container Operators (TCOs) are striving to maximize profit through the integration of their global Tank Container (TC) operations with the job quotation-booking process. However, TCOs face a set of unique challenges not faced by general shipping container operators, including the process uncertainties arising from TC cleaning and the use of Freight Forwarders (FFs). In this paper, a simulation-based two-stage optimization model is developed to address these challenges. The first stage focuses on tactical decisions of setting inventory levels and control policy for empty container repositioning. The second stage integrates the dynamic job acceptance/rejection decisions in the quotation-booking processes with container operations decisions in the planning and execution processes, such as job fulfillment, container leasing terms, choice of FFs considering cost and reliability, and empty tank container repositioning. The solution procedure is based on the simulation model combined with heuristic algorithms including an adjusted Genetic Algorithm, mathematical programming, and heuristic rules. Numerical examples based on a real case study are provided to illustrate the effectiveness of the model

해운물류에서의 접이식 컨테이너 효과 분석

학위논문(박사) -- 서울대학교대학원 : 공과대학 산업공학과, 2022.2. 문일경.컨테이너 화 이후로 해상 물류는 폭발적으로 증가하였고 세계화와 산업 발전을 선도하였다. 하지만 무역량의 증가와 비례하여 수출입 불균형으로 인한 컨테이너의 불균형 문제도 심화되었다. 이러한 문제를 해결하기 위해 다양한 연구자들의 노력이 있었고, 그 중 접이식 컨테이너라는 새로운 개념의 컨테이너가 개발되었다. 하지만 아직 접이식 컨테이너는 상용화 초기 단계이며, 이를 활용한 여러 효과에 대한 연구는 부족한 실정이다. 본 논문에서는 접이식 컨테이너가 도입되었을 때 미칠 수 있는 영향과 그 효과에 대해 다루었다. 먼저 접이식 컨테이너가 크레인 활동에 미치는 영향을 분석하고, 전역적 관점으로 크레인 활동을 줄일 수 있는 방법에 대해 분석하였다. 두 번째로 육상에서의 접이식 컨테이너 적용이 해상과는 다르다는 점에 주목하여 그 효과를 분석하였다. 마지막으로 2008 금융위기와 COVID-19 이후에 증가하고 있는 해운물류의 각종 변동하는 상황 하에서의 접이식 컨테이너 효과에 대해 새로운 통찰을 제공하였다. 1장에서는 간단하게 컨테이너화와 접이식 컨테이너에 대해 설명하고 문제를 주목하게 된 이유와 그 성과를 서술하였다. 2장에서는 접이식 컨테이너가 도입됨에 따라 생길 수 있는 ‘상단 적재 규칙’이 적용되었을 때의 크레인 활동의 변화를 살펴보고 전역적 최적화가 지역적 최적화보다 효과적임을 보였다. 더불어 전역적 최적화를 도입하였을 때 직면할 수 있는 비용 분배 문제에 대해서도 조망하여 그 해결책을 제시하였다. 3장에서는 육상에서 접이식 컨테이너가 수송공간을 줄여주는 장점 외에 경로를 바꾸는 효과가 존재함을 보이고, 다양한 시나리오와 정책에 따라 그 효과가 어떻게 변화하는지에 대해 분석하였다. 4장에서는 증가하는 다양한 변동상황 각각에 대해 접이식 컨테이너의 효과에 대해 분석하였다. 이를 토대로 각 상황에 맞는 최적 접이식 컨테이너 개수를 도출하고 임대 정책을 통해 대응할 수 있다는 통찰을 도출하였다. 5장에서는 본 논문의 결론과 향후 연구 방안에 대해 서술하였다. 본 논문에서 제안하는 문제와 그 해결 방법은 학술적 및 산업적으로 의미가 있다. 학계에는 실제 존재하는 현장의 문제들을 제시하고 문제를 효과적으로 해결할 수 있는 방법들을 제안한다. 산업계에는 신기술인 접이식 컨테이너의 도입에 따라 발생할 수 있는 문제에 대해 정량화 및 모형화를 통한 해결방법을 제시한다. 본 논문을 통해 산업의 발전과 학문의 발전이 함께 이루어질 수 있을 것으로 기대한다.After containerization, maritime logistics experienced the substantial growth of trade volumes and led to globalization and industrial development. However, in proportion to the increase in the volume, the degree of container imbalance also intensified due to the disparity between importing and exporting sizes at ports in different continents. A group of researchers is digging into resolving this ongoing challenge, and a new concept of a container, called a foldable container, has been proposed. Nevertheless, foldable containers are still in the early stage of commercialization, and research on the various effects of using foldable containers seems insufficient yet. This dissertation considers the possible effects of the introduction of foldable containers. First, we analyze the effect of foldable containers on crane operation and reduce shifts from a global perspective. Second, the effect of using foldable containers in hinterland areas was analyzed by noting that the application of foldable containers on land was different from that of the sea. Finally, we provided new insights into the foldable container under plausible dynamic situations in the shipping industry during the COVID-19 and logistics that have increased since the 2008 financial crisis. A brief explanation of containerization and foldable containers is introduced in Chapter 1, along with the dissertation's motivations, contributions, and outlines. Chapter 2 examines changes in crane operation when the 'top stowing rule' that can be treated with foldable containers is applied and shows that global optimization is more effective than local optimization. In addition, we suggested the cost-sharing method to deal with fairness issues for additional costs between ports when the global optimization method is fully introduced. Chapter 3 shows that foldable containers in the hinterland have the effect of changing routes in addition to reducing transportation space and analyzes how the results change according to various scenarios and policies. Chapter 4 analyzes the effectiveness of foldable containers for different dynamic situations. Moreover, the managerial insight was derived that the optimal number of foldable containers suitable for each situation can be obtained and responded to leasing policies. Chapter 5 describes the conclusions of this dissertation and discusses future research. The problem definition and solution methods proposed in this dissertation can be seen as meaningful in both academic and industrial aspects. For academia, we presented real-world problems in the field and suggested ways to solve problems effectively. For industry, we offered solutions through quantification and modeling for real problems related to foldable containers. We expect that industrial development and academic achievement can be achieved together through this dissertation.Chapter 1 Introduction 1 1.1 Containerization and foldable container 1 1.2 Research motivations and contributions 3 1.3 Outline of the dissertation 6 Chapter 2 Efficient stowage plan with loading and unloading operations for shipping liners using foldable containers and shift cost-sharing 7 2.1 Introduction 7 2.2 Literature review 10 2.3 Problem definition 15 2.4 Mathematical model 19 2.4.1 Mixed-integer programming model 19 2.4.2 Cost-sharing 24 2.5 Computational experiment and analysis 26 2.6 Conclusions 34 Chapter 3 Effects of using foldable containers in hinterland areas 36 3.1 Introduction 36 3.2 Single depot repositioning problem 39 3.2.1 Problem description 40 3.2.2 Mathematical formulation of the single depot repositioning problem 42 3.2.3 Effects of foldable containers 45 3.3 Multi-depot repositioning problem 51 3.4 Computational experiments 56 3.4.1 Experimental design for the SDRP 57 3.4.2 Experimental results for the SDRP 58 3.4.3 Major and minor effects with the single depot repositioning problem 60 3.5 Conclusions 65 Chapter 4 Effect of foldable containers in dynamic situation 66 4.1 Introduction 66 4.2 Problem description 70 4.3 Mathematical model 73 4.4 Computational experiments 77 4.4.1 Overview 77 4.4.2 Experiment results 79 4.5 Conclusions 88 Chapter 5 Conclusion and future research 90 Bibliography 94 국문초록 99박

Economic Analysis of Marine Transportation using Foldable Container

Today, businesses are faced with problems such as rapidly changing technology, infinite competition and uncertainty of economic growth. To solve these problems, many companies are trying to strengthen their competitiveness by sharing resources and profits, spreading the risk of large-scale investment through collaboration. In particular, logistics companies are sensitive to changes in the economy. The Korean shipping industry has been in a state of crisis since the 2008 global financial crisis, with the ongoing recession and prolonged oversupply and shipping depression. Korea's international freight transport accounts for more than 90% of the import and export volume. These maritime transports are linked to the land and the cargo is transported in the form of multimodal transport. Containers carry these cargoes and are transported to their destination through various logistics bases in the form of composite transportation using transportation means such as ships, automobiles, and railways. Globally, 30 container shipping companies are paying about $ 20 billion a year for repositioning of empty containers. This is due to the imbalance in world trade and mainly to relocate public containers to Asia. The introduction of folding containers in maritime transport can be one of the solutions to this problem. Because Jeju Island is geographically island, Korea must use sea or air transportation in economic activities with the inland, and logistics cost is relatively high. Therefore, in order to improve the competitiveness of the region or to achieve the goal of implementing Jeju as an eco-friendly island, it is necessary to utilize the logistics related resources as much as possible to reduce costs and minimize the environmental pollution. In addition to its environmentally friendly features, folding containers are also recognized as a means of reducing total logistics costs such as marine transportation and land transportation. This study proposes the use of folding containers for marine transportation between Jeju and Mokpo, and analyzes the economics through various scenarios when folding containers are operated. Based on the conclusions, Various suggestions are also presented.표목차 ⅴ 그림목차 ⅶ 영문초록(Abstract) ⅸ 1. 서 론 1 1.1 연구의 배경 및 필요성 1 1.1.1 연구의 배경 1 1.1.2 연구의 필요성 2 1.2 연구의 목적 및 범위 5 1.2.1 연구의 목적 5 1.2.2 연구의 범위 6 1.3 연구의 방법 및 구성 7 1.4 선행연구와의 차별성 9 2. 이론적 고찰 10 2.1 제주-목포 항로에 관한 선행연구 10 2.2 공 컨테이너 재배치에 관한 선행연구 12 2.3 접이식 컨테이너에 관한 선행연구 17 2.4 접이식 컨테이너의 개발현황 20 2.5 Container Pool System에 관한 선행연구 25 2.5.1 Container Pool System의 정의 25 2.5.2 Container Pool System의 특징과 선행연구 25 3. 제주-목포간의 해상운송의 현황과 문제점 28 3.1 제주-목포간의 해상운송 특성 및 현황과 문제점 28 3.1.1 제주도의 지리적 특성 28 3.1.2 제주-목포간의 해상운송의 현황 30 3.1.3 제주-목포간의 해상물류의 문제점 34 3.2 제주-목포간의 해상운송의 형태와 컨테이너 이용실태 36 3.2.1 제주-목포간의 해상운송의 형태 36 3.2.2 제주-목포간의 컨테이너 이용 실태 38 3.2.3 제주-목포간의 컨테이너 운영방식 42 4. 시나리오 적용과 시뮬레이션 43 4.1 시나리오 플래닝 43 4.2 시뮬레이션 46 4.2.1 시뮬레이션 모델 46 4.2.2 제주-목포항로의 시뮬레이션 48 4.3 컨테이너 운영비용 분석 50 4.3.1 One Cycle(Shipper to Consignee)비용 분석 50 4.3.2 One Cycle(Port to Port)비용 분석 52 4.3.3 One-way Empty Container repositioning비용 분석 53 5. 경제성 비교분석 55 5.1 운영구간에 따른 비교분석 55 5.2 제주-목포항로 물동량에 따른 비교분석 56 5.3 제주-목포항로 공 컨테이너 재배치 비용 비교 분석 57 5.4 민감도 분석 60 6. 결론 65 6.1 연구결과의 요약 및 시사점 65 6.2 연구의 한계점 및 향후 연구 방향 67 감사의 글 68 참고문헌 69 부록 2016년도 항만하역요금표 71Maste

공컨테이너관리 기법을 활용한 효율적인 컨테이너 공급망

학위논문 (박사) -- 서울대학교 대학원 : 공과대학 산업공학과, 2021. 2. 문일경.Due to a remarkable surge in global trade volumes led by maritime transportation, shipping companies should make a great effort in managing their container flows especially in case of carrier-owned containers. To do so, they comprehensively implement empty container management strategies and accelerate the flows in a cost- and time-efficient manner to minimize total relevant costs while serving the maximal level of customers demands. However, many critical issues in container flows universally exist due to high uncertainty in reality and hinder the establishment of an efficient container supply chain. In this dissertation, we fully discuss such issues and provide mathematical models along with specific solution procedures. Three types of container supply chain are presented in the following: (i) a two-way four-echelon container supply chain; (ii) a laden and empty container supply chain under decentralized and centralized policies; (iii) a reliable container supply chain under disruption. These models explicitly deal with high risks embedded in a container supply chain and their computational experiments offer underlying managerial insights for the management in shipping companies. For (i), we study empty container management strategy in a two-way four-echelon container supply chain for bilateral trade between two countries. The strategy reduces high maritime transportation costs and long delivery times due to transshipment. The impact of direct shipping is investigated to determine the number of empty containers to be repositioned among selected ports, number of leased containers, and route selection to satisfy the demands for empty and laden containers for exporters and importers in two regions. A hybrid solution procedure based on accelerated particle swarm optimization and heuristic is presented, and corresponding results are compared. For (ii), we introduce the laden and empty container supply chain model based on three scenarios that differ with regard to tardiness in the return of empty containers and the decision process for the imposition of fees with the goal of determining optimal devanning times. The effectiveness of each type of policy - centralized versus decentralized - is determined through computational experiments that produce key performance measures including the on-time return ratio. Useful managerial insights on the implementation of these polices are derived from the results of sensitivity analyses and comparative studies. For (iii), we develop a reliability model based on container network flow while also taking into account expected transportation costs, including street-turn and empty container repositioning costs, in case of arc- and node-failures. Sensitivity analyses were conducted to analyze the impact of disruption on container supply chain networks, and a benchmark model was used to determine disruption costs. More importantly, some managerial insights on how to establish and maintain a reliable container network flow are also provided.해상 수송이 주도함으로써 전 세계 무역량이 급증하기 때문에 회사 소유 컨테이너는 컨테이너 흐름을 관리하는 데 많은 노력을 기울여야 한다. 이를 위해 공 컨테이너 관리 전략을 포괄적으로 구현하고 효율적인 수송 비용 및 시간 절감 방식으로 컨테이너 흐름을 원활히 하여 관련 총비용을 최소화하는 동시에 고객의 수요를 최대한 충족하게 된다. 그러나 현실에서는 높은 불확실성 때문에 컨테이너 흐름에 대한 많은 주요한 이슈가 보편적으로 존재하고 효율적인 컨테이너 공급망 구축을 방해한다. 본 논문에서는 이러한 이슈에 대해 전반적으로 논의하고 적절한 해법과 함께 수리 모형을 제공한다. 이를 위해 세 가지 유형의 컨테이너 공급망을 다룬다. 먼저 (i) 양방향 네 단계 컨테이너 공급망, (ii) 분권화 및 중앙 집중화 정책에 따른 적∙공 컨테이너 공급망; 그리고 (iii) disruption 상황 속에서 신뢰성을 고려하는 컨테이너 공급망이다. 본 논문에서 제시한 세 가지 모형은 컨테이너 공급망에 내재 된 높은 위험을 직접 다루며 계산 실험은 해운 회사의 경영진이나 관계자를 위해 주요한 관리 인사이트를 제공한다. (i)의 경우, 두 지역 간 양자 무역을 위한 양방향 네 단계 컨테이너 공급망에서 공 컨테이너 관리 전략을 연구한다. 이 전략은 환적으로 인한 높은 해상 운송 비용과 긴 배송 시간을 줄일 수 있다. 또한, 직항 수송의 영향을 조사하여 선택된 항구 중 재배치 할 공 컨테이너 수, 임대 컨테이너 수, 두 지역의 수출업자와 수입업자의 적∙공 컨테이너 대한 수요를 만족하기 위한 경로 선택을 결정하게 된다. APSO 및 휴리스틱을 기반으로 하는 하이브리드 해법을 제시하며 비교 실험을 하였다. (ii)의 경우 최적 devanning time 결정을 목표로 공 컨테이너의 반환 지연과 해당 수수료 부과 결정 프로세스와 관련하여 서로 다른 세 가지 시나리오를 기반으로 적∙공 컨테이너 공급망 모형을 제시한다. 각 유형의 정책적(분권화 및 중앙 집중화) 효과는 정시 반환율을 포함한 주요 성능 측정을 고려하는 계산 실험을 통해 결정된다. 이러한 정책 실행에 대한 유용한 관리 인사이트는 민감도 분석 및 비교 연구의 결과에서 도출한다. (iii)의 경우, 본 논문은 컨테이너 네트워크 흐름을 기반으로 하는 신뢰성 모형을 개발하는 동시에 아크 및 노드 failure가 있을 때 street-turn 및 공 컨테이너 재배치 비용을 포함한 기대 총 비용을 구한다. 중단이 컨테이너 공급망 네트워크에 미치는 영향을 분석하기 위해 민감도 분석을 수행했으며 disruption 비용을 결정하기 위해 벤치마크 모형을 활용한다. 더불어 신뢰성을 고려한 컨테이너 네트워크 흐름을 구축하고 신뢰성을 유지하는 방법에 대한 관리적 인사이트도 제공한다.Abstract i Contents ii List of Tables vi List of Figures viii 1. Introduction 1 1.1 Empty Container Repositioning Problem 1 1.2 Reliability Problem 3 1.3 Research Motivation and Contributions 4 1.4 Outline of the Dissertation 7 2. Two-Way Four-Echelon Container Supply Chain 8 2.1 Problem Description and Literature Review 8 2.2 Mathematical Model for the TFESC 15 2.2.1 Overview and Assumptions 15 2.2.2 Notation and Formulation 19 2.3 Solution Procedure for the TFESC 25 2.3.1 Pseudo-Function-based Optimization Problem 25 2.3.2 Objective Function Evaluation 28 2.3.3 Heuristics for Reducing the Number of Leased Containers 32 2.3.4 Accelerated Particle Swarm Optimization 34 2.4 Computational Experiments 37 2.4.1 Heuristic Performances 39 2.4.2 Senstivity Analysis of Varying Periods 42 2.4.3 Senstivity Analysis of Varying Number of Echelons 45 2.5 Summary 48 3. Laden and Empty Container Supply Chain under Decentralized and Centralized Policies 50 3.1 Problem Description and Literature Review 50 3.2 Scenario-based Model for the LESC-DC 57 3.3 Model Development for the LESC-DC 61 3.3.1 Centralized Policy 65 3.3.2 Decentralized Policies (Policies I and II) 67 3.4 Computational Experiments 70 3.4.1 Numerical Exmpale 70 3.4.2 Sensitivity Analysis of Varying Degree of Risk in Container Return 72 3.4.3 Sensitivity Analysis of Increasing L_0 74 3.4.4 Sensitivity Analysis of Increasing t_r 76 3.4.5 Sensitivity Analysis of Decreasing es and Increasing e_f 77 3.4.6 Sensitivity Analysis of Discounting 〖pn〗_{f1} and 〖pn〗_{f2} 78 3.4.7 Sensitivity Analysis of Different Container Fleet Sizes 79 3.5 Managerial Insights 81 3.6 Summary 83 4. Reliable Container Supply Chain under Disruption 84 4.1 Problem Description and Literature Review 84 4.2 Mathematical Model for the RCNF 90 4.3 Reliability Model under Disruption 95 4.3.1 Designing the Patterns of q and s 95 4.3.2 Objective Function for the RCNF Model 98 4.4 Computational Experiments 103 4.4.1 Sensitivity Analysis of Expected Failure Costs 106 4.4.2 Sensitivity Analysis of Different Network Structures 109 4.4.3 Sensitivity Analysis of Demand-Supply Variation 112 4.4.4 Managerial Insights 115 4.5 Summary 116 5. Conclusions and Future Research 117 Appendices 120 A Proof of Proposition 3.1 121 B Proof of Proposition 3.2 124 C Proof of Proposition 3.3 126 D Sensitivity Analyses for Results 129 E Data for Sensitivity Analyses 142 Bibliography 146 국문초록 157 감사의 글 160Docto

Maritime Empty Container Repositioning with Inventory-based Control

Ph.DDOCTOR OF PHILOSOPH

Operational model for empty container repositioning

Ph.DDOCTOR OF PHILOSOPH

Models and algorithms for the empty container repositioning and its integration with routing problems

The introduction of containers has fostered intermodal freight transportation. A definition of intermodality was provided by the European Commission as “a characteristic of a transport system whereby at least two different modes are used in an integrated manner in order to complete a door-to-door transport sequence”. The intermodal container transportation leads to several benefits, such as higher productivity during handling phases and advantages in terms of security, losses and damages. However, the distribution of containers comes with a drawback: due to directional imbalances in freight flows, some areas tend to accumulate unnecessary empty containers, while others face container shortages. Several planning models were developed for carriers in order to manage both loaded and empty containers profitably. However, they were built to operate under normal circumstances, neglecting the fact that networks are increasingly affected by both uncertainty and vulnerability, which may result in disruptions. The thesis aims to survey whether the impact of uncertainty can be mitigated by a stochastic programming approach, in which disruptions and normal operations are both foreseen as possible futures or scenarios. This approach is carried out by a multi-scenario optimization model in which scenarios are linked by non-anticipativity conditions. The empty container repositioning becomes even more challenging and difficult when integrated with routing problems. In fact, carriers often face problems in which they must determine simultaneously how many empty containers are carried by a fleet of vehicles and which routes must be followed by these vehicles. These problems typically arise in inland networks, in which one must plan the distribution by trucks of loaded and empty containers to customers. The thesis addresses this type of vehicle routing problems, which are motivated by a real case study occurred during the collaboration with a carrier that operates in the Mediterranean Sea in door-to-door modality. The carrier manages a fleet of trucks based at the port. Trucks and containers are used to service two types of transportation requests, the delivery of container loads from the port to import customers, and the shipment of container loads from export customers to the port. The thesis addresses two problems which differ in the composition of the fleet of trucks. The first problem involves a heterogeneous fleet of trucks that can carry one or two containers. We present a Vehicle Routing Problem with backhauls, load splits into multiple visits, and the impossibility to separate trucks and containers during customer service. Then, we formalize the problem by an Integer Linear Programming formulation and propose an efficient meta-heuristic algorithm able to solve it. The meta-heuristic determines the initial solution by a variant of the Clarkeand-Wright algorithm, and improves it by several local search phases, in which both node movements and truck swaps are implemented. The second problem involves a homogeneous fleet of trucks that can carry more than a container. As a consequence, the identification of routes can be more difficult. We present and formalize the associated Vehicle Routing Problem by an Integer Linear Programming formulation. Then we propose an efficient adaptive guidance meta-heuristic algorithm able to solve it. The meta-heuristic determines an initial feasible solution by a Tabu Search step, and next improves this solution by appropriate adaptive guidance mechanisms

Models and algorithms for the empty container repositioning and its integration with routing problems

The introduction of containers has fostered intermodal freight transportation. A definition of intermodality was provided by the European Commission as “a characteristic of a transport system whereby at least two different modes are used in an integrated manner in order to complete a door-to-door transport sequence”. The intermodal container transportation leads to several benefits, such as higher productivity during handling phases and advantages in terms of security, losses and damages. However, the distribution of containers comes with a drawback: due to directional imbalances in freight flows, some areas tend to accumulate unnecessary empty containers, while others face container shortages. Several planning models were developed for carriers in order to manage both loaded and empty containers profitably. However, they were built to operate under normal circumstances, neglecting the fact that networks are increasingly affected by both uncertainty and vulnerability, which may result in disruptions. The thesis aims to survey whether the impact of uncertainty can be mitigated by a stochastic programming approach, in which disruptions and normal operations are both foreseen as possible futures or scenarios. This approach is carried out by a multi-scenario optimization model in which scenarios are linked by non-anticipativity conditions. The empty container repositioning becomes even more challenging and difficult when integrated with routing problems. In fact, carriers often face problems in which they must determine simultaneously how many empty containers are carried by a fleet of vehicles and which routes must be followed by these vehicles. These problems typically arise in inland networks, in which one must plan the distribution by trucks of loaded and empty containers to customers. The thesis addresses this type of vehicle routing problems, which are motivated by a real case study occurred during the collaboration with a carrier that operates in the Mediterranean Sea in door-to-door modality. The carrier manages a fleet of trucks based at the port. Trucks and containers are used to service two types of transportation requests, the delivery of container loads from the port to import customers, and the shipment of container loads from export customers to the port. The thesis addresses two problems which differ in the composition of the fleet of trucks. The first problem involves a heterogeneous fleet of trucks that can carry one or two containers. We present a Vehicle Routing Problem with backhauls, load splits into multiple visits, and the impossibility to separate trucks and containers during customer service. Then, we formalize the problem by an Integer Linear Programming formulation and propose an efficient meta-heuristic algorithm able to solve it. The meta-heuristic determines the initial solution by a variant of the Clarkeand-Wright algorithm, and improves it by several local search phases, in which both node movements and truck swaps are implemented. The second problem involves a homogeneous fleet of trucks that can carry more than a container. As a consequence, the identification of routes can be more difficult. We present and formalize the associated Vehicle Routing Problem by an Integer Linear Programming formulation. Then we propose an efficient adaptive guidance meta-heuristic algorithm able to solve it. The meta-heuristic determines an initial feasible solution by a Tabu Search step, and next improves this solution by appropriate adaptive guidance mechanisms

Port choice: A frequency-based container assignment model

The process of containerization has connected the world with a cost-effective freight service, successfully forming a competitive global market. Mixed freight shipping has changed dramatically due to containerization and globalization. The port system has experienced a tough time keeping pace with globalisation in terms of its roles and functions in liner shipping. Consequently, port choice has become a challenging problem to analyse with many stakeholders and complex circumstances. The literature formulating the basis of this maritime container assignment model can be identified as a combination of port choice modelling, a freight flow model and empty container repositioning. It is observed that the maritime container assignment problem shares a greater affinity with transit assignment than with traffic assignment conventionally applied freight in the four step approach, because containers are generally carried by shipping lines which operate services on fixed routes or port rotations. A model capable of representing full and empty container flows at a global level would be useful to almost every stakeholder in the container liner shipping industry, such as shippers, shipping lines, port authorities, terminal operating companies, regional and national planning authorities, marine insurance companies, and others. The classic frequency-based transit assignment approach of Spiess and Florian is transferred and applied to maritime containers as the foundation for a global maritime container assignment model. The first version of this model assigned full and empty containers to routes to minimise expected travel time, which consists of sailing time between ports and dwell time at intermediate transhipment ports. Service frequency and port capacity influence the pattern of full and empty container flows and therefore port choice. In this thesis, the model is further developed to fit the reality of container liner shipping by minimising expected cost rather than expected travel time. The objective is now to assign container flows to routes to minimize the sailing costs and expected dwell costs at the origin port and intermediate transhipment ports. The constraints included are extended to include the maximum number of containers each route can carry. Finally, the capabilities of the cost-based container assignment model are explored through a case study of the Europe-Far East trade lane. A range of strategy and policy options, such as a shipping line planning a new route or modifying an existing route and a port authority considering expansion, are simulated. A possible approach to model validation through independent data is proposed. Recommendations for future research are provided at the end of the thesis. Many aspects are covered in the thesis; an origin-destination matrix estimation, automated virtual (task) network construction from routes and schedules, improvements to the probability distribution used for ship arrivals, a validation procedure, and model extension from port-to-port movements to door-to-door container movements