This study will help better our understanding of the import-export processes in the U.S. It examines the challenges faced by US exporters and importers, and investigates an innovative solution to tackle these challenges. The dry port concept introduced by transportation geographers is discussed, and an intermodal rail costing model is used in determining whether this concept will prove to be a more sustainable and energy efficient system than what currently exists. / text

Expanderande städer resulterar i ökande behov av godstransporter och för att behålla en fungerande godsdistribution kan åtgärder behöva vidtas. Trafikstockning och försämrad stadsmiljö är negativa effekter som kan förknippas med en dåligt fungerande godsdistribution. Citylogistik handlar om att kontrollera och optimera godstransporter i urbana områden (city) så att negativa effekter minimeras. Olika typer av citylogistiska åtgärder och koncept har identifierats. Till dem hör till exempel samdistribution, reglering av godstransporter och avancerade IT-system. Inom ramen för projektet SAMLIC, som startades i Linköping 2004, genomfördes pilotförsöket PILOT med det övergripande syftet att utvärdera ekonomisk potential med samdistribution i Linköpings city. Under PILOT omsattes ett samdistributionskoncept i praktiken. En databas med information om godsdistributionen under försöket upprättades för senare analys. Syftet med detta examensarbete har varit att formulera matematiska modeller över godsdistributionen i ett medelstort city, som kan ge underlag för utvärdering av citylogistiska koncept och i synnerhet samdistributionskoncept. De matematiska modeller som tagits fram är optimeringsmodeller för ruttplanering och metoder för att lösa optimeringsmodellerna har implementerats. För att utvärdera modellerna och metoderna har en fallstudie av Linköpings city gjorts, med datamaterial från PILOT. Modellerna ger möjlighet till effektiva analyser och jämförelser av citylogistiska koncept. Fallstudien visar dessutom att optimering av godsdistributionen i city innebär god förbättringspotential vilket ger ytterligare motiv till att använda modeller som verktyg. / Urbanization and city expansion result in an increasing need of transportation of goods, and in order to maintain efficiency, measures are needed. The aim of city logistics is to minimize negative impacts associated with city center goods distribution, such as traffic congestion and negative impacts on the living environment. Several city logistic measures have previously been suggested, such as freight consolidation, governance and advanced IT systems. Within the SAMLIC project started in 2004, a demonstration project known as PILOT was carried out in central Linköping, wherein the concept of freight consolidation was applied in reality. The objective was to evaluate the economic potential of freight consolidation. The aim of this thesis was to formulate mathematical models of the distribution of goods in a medium sized Swedish city. The models are to be used in the evaluation of city logistic measures, focusing on freight consolidation. The distribution problem is modelled as a vehicle routing problem, and methods for solving the resulting optimization problems have been implemented. Using data from PILOT, the models have been applied on Linköping with the purpose of evaluating the methods, as well as investigating the potential of using models for planning the distribution of goods. Conclusions involve that analyses of, and comparisons between, city lo-gistic measures can be efficiently made using mathematical models. The case study also indicates that goods distribution can be improved through the use of optimization methods, which further motivates mathematical modelling.

Shipment Consolidation (SCL) is a logistics strategy that combines two or more orders or shipments so that a larger quantity can be dispatched on the same vehicle to the same market region. This dissertation aims to emphasize the importance and substantial cost saving opportunities that come with SCL in a logistics supply chain, by offering new models or by improving on the current body of literature. Our research revolves around "three main axes" in SCL: Single-Item Shipment Consolidation (SISCL), Multi-Item Shipment Consolidation (MISCL), and Pricing and Shipment Consolidation. We investigate those topics by employing various Operations Research concepts or techniques such as renewal theory, dynamic optimization, and simulation. In SISCL, we focus on analytical models, when the orders arrive randomly. First, we examine the conditions under which an SCL program enables positive savings. Then, in addition to the current SCL policies used in practice and studied in the literature, i.e. Quantity-Policy (Q-P), Time-Policy (T-P) and Hybrid Policy (H-P), we introduce a new one that we call the Controlled Dispatch Policy (CD-P). Moreover, we provide a cost-based comparison of those policies. We show that the Q-P yields the lowest cost per order amongst the others, yet with the highest randomness in dispatch times. On the other hand, we also show that, between the service-level dependent policies (i.e. the CD-P, H-P and T-P), H-P provides the lowest cost per order, while CD-P turns out to be more flexible and responsive to dispatch times, again with a lower cost than the T-P. In MISCL, we construct dispatch decision rules. We employ a myopic analysis, and show that it is optimal, when costs and the order-arrival processes are dependent on the type of items. In a dynamic setting, we apply the concept of time-varying probability to integrate the dispatching and load planning decisions. For the most common dispatch objectives such as cost per order, cost per unit time or cost per unit weight, we use simulation and observe that the variabilities in both cost and the optimal consolidation cycle are smaller for the objective of cost per unit weight. Finally on our third axis, we study the joint optimization of pricing and time-based SCL policy. We do this for a price- and time-sensitive logistics market, both for common carriage (transport by a public, for-hire trucking company) and private carriage (employing one's own fleet of trucks). The main motivation for introducing pricing in SCL decisions stems from the fact that transportation is a service, and naturally demand is affected by price. Suitable pricing decisions may influence the order-arrival rates, enabling extra savings. Those savings emanate from two sources: Scale economies (in private carriage) or discount economies (in common carriage) that come with SCL, and additional revenue generated by employing an appropriate pricing scheme. Throughout the dissertation, we offer numerical examples and as many managerial insights as possible. Suggestions for future research are offered.

Shipment Consolidation (SCL) is a logistics strategy that combines two or more orders or shipments so that a larger quantity can be dispatched on the same vehicle to the same market region. This dissertation aims to emphasize the importance and substantial cost saving opportunities that come with SCL in a logistics supply chain, by offering new models or by improving on the current body of literature. Our research revolves around "three main axes" in SCL: Single-Item Shipment Consolidation (SISCL), Multi-Item Shipment Consolidation (MISCL), and Pricing and Shipment Consolidation. We investigate those topics by employing various Operations Research concepts or techniques such as renewal theory, dynamic optimization, and simulation. In SISCL, we focus on analytical models, when the orders arrive randomly. First, we examine the conditions under which an SCL program enables positive savings. Then, in addition to the current SCL policies used in practice and studied in the literature, i.e. Quantity-Policy (Q-P), Time-Policy (T-P) and Hybrid Policy (H-P), we introduce a new one that we call the Controlled Dispatch Policy (CD-P). Moreover, we provide a cost-based comparison of those policies. We show that the Q-P yields the lowest cost per order amongst the others, yet with the highest randomness in dispatch times. On the other hand, we also show that, between the service-level dependent policies (i.e. the CD-P, H-P and T-P), H-P provides the lowest cost per order, while CD-P turns out to be more flexible and responsive to dispatch times, again with a lower cost than the T-P. In MISCL, we construct dispatch decision rules. We employ a myopic analysis, and show that it is optimal, when costs and the order-arrival processes are dependent on the type of items. In a dynamic setting, we apply the concept of time-varying probability to integrate the dispatching and load planning decisions. For the most common dispatch objectives such as cost per order, cost per unit time or cost per unit weight, we use simulation and observe that the variabilities in both cost and the optimal consolidation cycle are smaller for the objective of cost per unit weight. Finally on our third axis, we study the joint optimization of pricing and time-based SCL policy. We do this for a price- and time-sensitive logistics market, both for common carriage (transport by a public, for-hire trucking company) and private carriage (employing one's own fleet of trucks). The main motivation for introducing pricing in SCL decisions stems from the fact that transportation is a service, and naturally demand is affected by price. Suitable pricing decisions may influence the order-arrival rates, enabling extra savings. Those savings emanate from two sources: Scale economies (in private carriage) or discount economies (in common carriage) that come with SCL, and additional revenue generated by employing an appropriate pricing scheme. Throughout the dissertation, we offer numerical examples and as many managerial insights as possible. Suggestions for future research are offered.

Les centres de consolidation urbaine sont une mesure populaire dans la logistique urbaine visant à rationaliser les trajets liés aux livraisons en ville. Cependant, bien que les avantages environnementaux de ce type de dispositifs ont été largement abordés et documentés, un nombre important de cas d’implémentation n’ont pas parvenu à atteindre une participation suffisante et démontrer un modèle de fonctionnement viable. Les principaux obstacles liés à leur mise en œuvre relèvent des préoccupations financières et de l’acceptation de la part des acteurs de la logistique urbaine. Par conséquent, le succès de ces schémas logistiques est souvent conditionné par un fort soutien réglementaire et financier des pouvoirs publics. Récemment, de nouveaux types de modèles d'exploitation des centres de consolidation urbaine, proposant une gamme d'activités à valeur ajoutée, sont apparus, permettant une meilleure intégration de ces plateformes dans la chaîne d'approvisionnement. En outre, un grand nombre d'expériences récentes se concentrent sur la consolidation de fret à petite échelle, ce qui permet un assouplissement des besoins en ressources matérielles et humaines. L'objectif de cette thèse est d'étudier le potentiel des plates-formes de consolidation de fret urbaines de diminuer les coûts et d'améliorer les performances des chaînes logistiques urbaines. En particulier, la thèse traitera des facteurs qui influent sur la viabilité de ces schémas logistiques dans le cadre d'une économie de marché.La thèse est structurée autour de trois questions de recherche qui portent sur (1) la viabilité du modèle traditionnel du centre de consolidation urbain basé sur les activités de transbordement et de consolidation, (2) les impacts des mesures qui visent à soutenir la mise en œuvre des schémas de consolidation et le niveau d’approbation des acteurs de la logistique urbaine qui en découle, (3) l’impact des nouvelles approches dans le domaine de plates-formes de consolidation de marchandises en ville et en particulier des nouveaux modèles d’exploitation de centres de consolidation urbains et des plates-formes de micro-consolidation. En abordant ces aspects, la thèse démontre que le modèle du centre de consolidation urbain traditionnel peut présenter une alternative viable, mais que le succès de ces schémas logistiques est soumis à un grand nombre de conditions qui sont difficiles à satisfaire en pratique. La thèse identifie les mesures d'accompagnement qui peuvent à la fois accroître la participation dans le schéma de consolidation et l'acceptation des acteurs, ainsi que celles qui rencontrent une réponse plus mitigée de la part des acteurs. Enfin, la thèse identifie les avantages potentiels des nouveaux modèles d’exploitation de centres de consolidation ainsi que les avantages de la consolidation à petite échelle. / Urban consolidation centres are a popular measure in city logistics, which aims at rationalizing delivery trips in an urban area. However, although their environmental benefits have been extensively addressed and documented, many of the implementation cases fail to reach sufficient participation and demonstrate a viable business model. Some of the main barriers linked to their implementation are the financial concerns and the stakeholder acceptance. Consequently, the success of these schemes has often been subject to a strong regulatory and financial support from public authorities. Recently, new forms of urban consolidation centre operating models offering a range of value-added activities have appeared, allowing a better integration of these facilities in the overall supply chain. Furthermore, a large number of recent experiments focus on small-scale freight consolidation, relaxing the requirements for material and human resources. The objective of this thesis is to investigate the potential of urban freight consolidation platforms to decrease the costs and improve the performance of urban logistics chains. In particular, the thesis will address factors that influence the viability of these schemes in a framework of market economy.The thesis is structured around three research questions that address (1) the viability of the traditional urban consolidation centre model based on transhipment and consolidation activities (2) the impact of market-based accompanying measures for urban consolidation centre project implementation and the resulting level of stakeholder support and (3) the impact of new approaches in urban freight consolidation platforms and in particular those of new urban consolidation centres operating models and micro-consolidation platforms. By tackling these aspects, the thesis demonstrates that the traditional urban consolidation centre model can present a viable alternative but that the success of the scheme is subject to a large number of requirements that are often difficult to meet in practice. The thesis highlights accompanying measures that can both increase the expected participation in the consolidation scheme as well as the stakeholder acceptance of the scheme, and those that meet a less positive stakeholder response. Finally, the thesis identifies the potential benefits of new operating models of urban consolidation centres and of small-scale consolidation. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished