This diploma focuses on the real use of operations research methods in conjunction with logistics technologies. The aim is to show the way of optimization and simulation methods application and to evaluate if these methods are suitable tools for logistics technology application. Following logistic technologies were analysed: Just in Time, Kanban, Cross-Docking and Hub and Spoke. Used mathematical tools include: mixed linear programming models, distribution models, methods of multi-criteria evaluation and simulation models. On the basis of mathematical models 4 examples of new technologies introduction or analysis of already functioning systems have been solved.

In an era where automation has been transforming the industrial arena, it is important not to lose focus on the health of employees who are still engaged in manual work. Employee health both physical and mental plays a vital role in the overall performance of a company, so it must be taken care of. In the case of cross-docking warehouses where there is a need for manual laborers due to the intricacies in handling products of various sizes and weights, the importance of taking care of the health of its employees becomes more vital. In the modern world of the supply chain, a cross-docking warehouse plays a vital role in providing more efficiency to the system. The type of goods handled by these cross-docking warehouses is vast and this, in turn, brings about the need to implement manual labor onto the production. This study focuses on the main physical and psychosocial problems faced by the workers in a cross-docking warehouse and how it can be improved. Here questionnaires and interviews are used to study and develop better practices and methods to improve everyday work. This thesis focuses on one of the largest cross-docking warehouses situated in Jönköping, Sweden. Here COPSOQ version III is used to find the various main psychosocial problem areas faced by the employees and unstructured interviews are used to pinpoint the main physical problems and their causes. Preventive measures to combat the problems are suggested and are supported by literature reviews.

The less-than-truckload (LTL) industry is highly competitive, with recent average profit margins less than 3%. LTL shipments are routed through a network of service centers and hubs. The performance of the entire LTL distribution network is highly dependent on the speed and accuracy of the hub operations. The focus of this research effort is to improve hub operations in order to reduce costs and increase service performance levels. Specifically, new approaches are investigated for assigning trailers to dock doors and sequencing the unloading of shipments at hubs. This thesis reviews current industry practices and available research literature on hub operations. Solution approaches for the trailer-to-door assignment and freight sequencing problems are presented along with case study results. The main performance measures are bottleneck time, total labor time, and total travel distance. For the trailer-to-door assignment problem, also referred to as the hub layout problem, the three approaches investigated are the original approach, a semi-permanent approach, and a dynamic approach. For the freight sequencing problem, the five approaches evaluated are trailer-at-a-time, trailer-at-a-time with offloading, nearest neighbor within a group, nearest neighbor within a shared group, and nearest neighbor. The approaches are implemented in C++ and analyzed using data from a regional LTL carrier. The case study results indicate that the dynamic layout performs significantly better than the original and semi-permanent layout for total distance, total labor time, and bottleneck time. For total distance and total labor time, the dynamic layout with nearest neighbor sequencing is the preferred approach. For bottleneck time, the dynamic layout with trailer-at-a-time with offloading performs best, while the nearest neighbor sequencing approach performs almost as well. In general, the case study results indicate that a dynamic layout with either a trailer-at-a-time with offloading approach or a nearest neighbor approach offers the largest potential for improvement. The assumptions and results of the hub layout and freight sequencing approaches are further evaluated using a simulation model. The simulation model indicates that a dynamic layout with nearest neighbor sequencing offers the largest potential for improvement in a more realistic environment with probabilistic and dynamic events. The simulation results also indicate that the trailer-at-a-time with offloading approach may need to be modified to account for more realistic dock conditions. In summary, the approaches explored in this research offer significant opportunity to improve hub operations through reducing bottleneck time, total labor time, and total travel distance. / Master of Science

Idag sker många transporter med låg utnyttjandegrad vilket gör att transportkostnaden per produkt blir hög samtidigt som transporter har en negativ påverkan på miljön. Genom att konsolidera transporter kan utnyttjandegraden av transporterna öka. Ökad utnyttjandegrad kan även hjälpa företagen att gå mot cirkulär ekonomi där målet är att utnyttja resurserna maximalt. För små och medelstora företag kan det dock vara svårt att bygga upp samarbeten med andra företag. Dessa företag möter olika möjligheter och hinder vid implementering av transportkonsolidering, därför kommer denna studien identifiera vilka dessa är.Studien har genomförts i samarbete med 16 företag i Orust kommun och har visat att de största hindren vid transportkonsolidering är kundkrav, produktkrav och informationsdelning. Företagen upplevde att kundernas krav på korta ledtider skulle göra det svårt att samordna transporter med andra företag. Många företag upplevde även att produktkraven deras produkter ställer på transporterna skulle försvåra transportkonsolidering. Studien kunde dock visa att flera företag hade liknande produktkrav vilket möjliggör transportkonsolidering. En del företag ansåg att det saknades stöd och samarbete för den informationsdelning som krävs vid konsolidering.De främsta möjligheterna som identifierades är företagskulturen och viljan att gå mot en mer hållbar distributionskedja. Företagen som deltog i intervjuerna nämnde att de såg positivt på transportkonsolidering om det fanns ett sätt att enkelt samordna transporterna. De är även aktiva i Orust Kretsloppsakademi som arbetar för ett hållbart Orust vilket visar att det finns ett intresse av att bli mer hållbara. / Today, many transports are at a low rate of utilization. This means that shipping costs per product will be high and at the same time transports have a negative impact on the environment. Consolidating transports can increase the utilization rate for transports which minimizes costs and environmental impact. Increased utilization rates can also help companies move towards circular economics where the goal is to maximize their utilization of resources. However, for small and medium size companies it may be difficult to build up partnerships with other companies. These companies face different possibilities and obstacles in implementing transport consolidation, therefore this study will identify these.The study has been carried out in cooperation with 16 companies in Orust and has shown that the main obstacles to transport consolidation are customer requirements, product requirements and information sharing. The companies perceived that customer demand for short lead times would make it difficult to coordinate transport with other companies. Many companies also found that the product requirements of their products on transport would make transport consolidation difficult. However, the study showed that several companies had similar product requirements, which enables transport consolidation. Some companies also felt that there was no support and cooperation for the information sharing required for consolidation.The main opportunities identified were corporate culture and the desire to move towards a more sustainable distribution chain. The companies that participated in the interviews mentioned that they can see possibilities of transport consolidation if there was a way to easily coordinate transport. They are also active in the Orust Kretsloppsakademi that works for a sustainable Orust, which shows that there is an interest in becoming more sustainable.

Background: Many processes play a critical role in making non-manufacturing operations work as optimal as possible. One of these processes that is an important part of these activities is the goods flow process. If this process does not function effectively, this can affect the entire business, which in turn will lead to huge costs and lead times. It is therefore important that the flow of goods in the terminal works well because customers nowadays require that goods that they place an order have to be delivered as soon as possible. Purpose: The aim of the study is to find solutions for streamlining flow of incoming and outgoing goods, which will reduce unnecessary transport distances between goods reception and delivery ports, as well as finding a solution for lack of surface. Methodology: All necessary information has been collected by using qualitative and quantitative data and with the help of various types of interviews: semi-structured and unstructured, as well as participating in observations to initiate process mapping and find new terminal design. Subsequently, cost savings were achieved by comparing the new and old terminal design, after that calculations were performed to see how much surface use was made more efficient with movement of LKM stock. Conclusion: By analyzing incoming goods flow and changing port usage in the terminal, in other words by increasing the number of ports for a department and by distributing goods flow between ports in an optimal manner, goods flow efficiency can be achieved. Non-manufacturing operations work can improve its productivity by optimizing floor space usage and eliminating waste and defects which effect goods handling. / Bakgrund: Många processer spelar kritisk roll för att icke-tillverkande verksamheter ska fungera så optimalt som möjligt. En av dessa processer som utgör en viktig del i sådana verksamheter är godsflödeprocessen. Om denna process inte fungerar på ett effektivt sätt kan det påverka hela verksamheten som i sin tur kommer att leda till stora kostnader och ledtider. Det är därför viktigt att godsflödet i terminalen fungerar väl eftersom kunder nuförtiden ställer höga krav på att gods som de lägger en beställning på skall levereras så snabbt så möjligt. Syfte: Studiens syfte är att hitta lösningar för att effektivisera flödet av in- och utgående gods som i sin tur kommer att minska onödiga truckkörningar mellan godsmottagning och utleverans portar, samt att optimera golvyta användning i terminalen. Metod: All nödvändig information har samlats in genom att använda kvalitativa och kvantitativa data och med hjälp av olika typer intervjuer: semi-strukturerade och ostrukturerade, samt genom deltagande observationer för att initiera processkartläggning och designa ny terminallayout. Därefter räknades kostnadsbesparingen fram som uppnåddes genom att jämföra den nya och gamla terminaldesignen, efter detta utfördes beräkningar för att se hur mycket användning av golvyta effektiviserades med LKM lager förflyttning. Slutsats: Genom att analysera inkommande godsflöde och ändra portanvändning i terminalen, det vill säga utöka antal portar för en avdelning samt genom att fördela godsflöde mellan portar på ett optimalt sätt kan godsflödeeffektivisering åstadkommas. Icke-tillverkande verksamhet kan förbättra sin produktivitet genom att optimera golvyta användning och eliminering av slöserier och brister i godshanteringen.

Dans le contexte économique actuel, les entreprises cherchent à développer de nouvelles stratégies de distribution pour leurs performances logistique. Dans cette quête de performances, les entreprises doivent adapter les stratégies de distribution misent en place avec les typologies de leurs produits. Plusieurs stratégies de distribution existent dans la chaîne logistique de grande distribution. Ces stratégies sont choisies sur la base des caractéristiques des produits, et /ou l'impact sur les performances logistiques. Dans cette thèse, nous étudions l'impact de trois stratégies de distribution, à savoir: stockage traditionnel, cross-docking pick by line et le cross-docking pick by store, sur trois performances de la logistiques, à savoir: le niveau de service, les coûts et le bullwhip effect. En outre, nous analysons l'impact des caractéristiques des produits sur les performances des stratégies de distribution et enfin proposer un cadre pour le choix de la stratégie la plus adaptée pour chaque produit. La chaîne logistique étudiée est composée de trois échelons: Centre de distribution du fournisseur, Centre de distribution du distributeur et les magasins. Basé sur un cas réel, nous effectuons une modélisation des processus, qui nous permet de développer un modèle déterministe de coût Macro et un modèle de simulation. Le modèle de coût macro permet d'évaluer l'impact des stratégies de distribution sur des coûts de la chaîne logistique. Après l'analyse macro des coûts, nous développons un modèle de simulation où nous intégrons les données relatives aux produits (la demande, le volume, etc.). Ce modèle permet une simulation dynamique du système la stratégie la plus adaptée pour chaque produit en fonction de ses caractéristiques et de l'impact sur les performances. A la fin de cette recherche, nous présentons une matrice de choix pour la segmentation des produits et choix de la stratégie de distribution. / Nowadays companies must look to develop new distribution strategies in order to achieve the required performance from their supply chain. In this quest, companies wonder about the consistency of their distribution strategies with the products they are selling. Several types of distribution strategies exist in the retail supply chain. These strategies are chosen based on the products characteristics, and/or the impact on the supply chain performances. In this research, we study the impact of three distribution strategies, namely: traditional warehousing, cross-docking pick by line and cross-docking pick by store, on three supply chain performances, namely: service level, cost and bullwhip effect. In addition, we analyse the impact of the products characteristics on the performances of the distribution strategies and propose a framework for choosing the right strategy for each product. The supply chain studied is composed of three echelons: Supplier Distribution Centre, Retailer Distribution Centre and Stores. Based a real business case, we perform a process modelling, that allows us to develop a deterministic Macro cost model and a simulation model. The macro cost model allows to evaluate the impact of the distribution strategies on the supply chain cost performance. After the macro cost analysis, we develop a simulation model where we integrate the data related to the products (demand, volume, ordering quantities etc.) in the model. This model allows a more dynamic simulation of the system in a large time period and determines the right strategy to select for each product depending on its characteristics and the impact on the performances. At the end of this research, we present a framework for product segmentation and distribution strategy selection.

Idag sker många transporter med låg utnyttjandegrad vilket gör att transportkostnaden per produkt blir hög samtidigt som transporter har en negativ påverkan på miljön. Genom att konsolidera transporter kan utnyttjandegraden av transporterna öka. Ökad utnyttjandegrad kan även hjälpa företagen att gå mot cirkulär ekonomi där målet är att utnyttja resurserna maximalt. För små och medelstora företag kan det dock vara svårt att bygga upp samarbeten med andra företag. Dessa företag möter olika möjligheter och hinder vid implementering av transportkonsolidering, därför kommer denna studien identifiera vilka dessa är. Studien har genomförts i samarbete med 16 företag i Orust kommun och har visat att de största hindren vid transportkonsolidering är kundkrav, produktkrav och informationsdelning. Företagen upplevde att kundernas krav på korta ledtider skulle göra det svårt att samordna transporter med andra företag. Många företag upplevde även att produktkraven deras produkter ställer på transporterna skulle försvåra transportkonsolidering. Studien kunde dock visa att flera företag hade liknande produktkrav vilket möjliggör transportkonsolidering. En del företag ansåg att det saknades stöd och samarbete för den informationsdelning som krävs vid konsolidering. De främsta möjligheterna som identifierades är företagskulturen och viljan att gå mot en mer hållbar distributionskedja. Företagen som deltog i intervjuerna nämnde att de såg positivt på transportkonsolidering om det fanns ett sätt att enkelt samordna transporterna. De är även aktiva i Orust Kretsloppsakademi som arbetar för ett hållbart Orust vilket visar att det finns ett intresse av att bli mer hållbara. / Today, many transports are at a low rate of utilization. This means that shipping costs per product will be high and at the same time transports have a negative impact on the environment. Consolidating transports can increase the utilization rate for transports which minimizes costs and environmental impact. Increased utilization rates can also help companies move towards circular economics where the goal is to maximize their utilization of resources. However, for small and medium size companies it may be difficult to build up partnerships with other companies. These companies face different possibilities and obstacles in implementing transport consolidation, therefore this study will identify these. The study has been carried out in cooperation with 16 companies in Orust and has shown that the main obstacles to transport consolidation are customer requirements, product requirements and information sharing. The companies perceived that customer demand for short lead times would make it difficult to coordinate transport with other companies. Many companies also found that the productrequirements of their products on transport would make transport consolidation difficult. However, the study showed that several companies had similar product requirements, which enables transport consolidation. Some companies also felt that there was no support and cooperation for the information sharing required for consolidation. The main opportunities identified were corporate culture and the desire to move towards a more sustainable distribution chain. The companies that participated in the interviews mentioned that they can see possibilities of transport consolidation if there was a way to easily coordinate transport. They are also active in the Orust Kretsloppsakademi that works for a sustainable Orust, which shows that there is an interest in becoming more sustainable.

På en alltmer global handelsplats med allt tuffare kundkrav handskas många företag med utmaningar kopplade till flexibilitet. Kunderna vill ha korta ledtider, stora anpassningsmöjligheter och utmärkt service, naturligtvis till ett lågt pris. Ytterligare en dimension av komplexitet adderas när stora koncerner gör förvärv av mindre bolag, vilket gör att koncernen måste säkerställa att även dessa nya förvärv kan möta kundens krav i samma utsträckning.  En lösning på denna problematik återfinns i litteraturen i konceptet logistikplattform. Konceptet innebär att ett företag arbetar med en centralt framtagen resursbas som sedan servar alla delar av företaget på en mer decentraliserad nivå för att kunna möta kundens krav. Fem viktiga byggstenar i en logistikplattform är central styrning, logistiska koncept, fysisk struktur, logistiska processer och aktiviteter samt informationssystem (Abrahamsson, et al., 2003).  I denna studie beskrivs koncernen Kesko, som i Sverige framför allt är aktiv inom byggbranschen och den tekniska handeln, med varumärkena K-Bygg, K-Rauta, Onninen samt Mark & Infra. Där återfinns denna problematik, speciellt kopplat till förvärv och kapaciteten på centrallagret som servar hela koncernen. Baserat på detta har denna studie syftet att utreda hur Kesko kan använda sig av en logistikplattform för att serva de olika varumärkena samt vad användandet får för konsekvens för centrallagret i Pilängen.  Studien fokuserar framförallt på de logistiska koncepten och den fysiska strukturen inom Kesko. De logistiska koncepten har avgränsats till att handla om försörjningskoncepten lagerhållning, kontinuerlig försörjning, leverantörsstyrt lager, cross-docking samt direktleverans och den fysiska strukturen har avgränsats till att hantera lokaliseringsstrategi, lagerstrategi samt transportstrategi.  Baserat på Keskos kunders, leverantörers samt produkters karaktäristik utformas vilka krav detta ställer på en logistikplattformen. Baserat på denna karaktäristik och krav utreds en ideal bild av Keskos logistikplattform i form av försörjningskoncept och den fysiska strukturen. Sedan utreds hur Kesko i nuläget verkligen arbetar med försörjningskoncepten och den fysiska strukturen. Dessa två versioner, den ideala bilden och nuläget, jämförs sedan i en så kallad gap-analys där skillnader utreds för att upptäcka var förbättringspotential finns och vilka förändringar Kesko kan genomföra för att kunna sägas jobba mot konceptet logistikplattform.  Analysen visar att Kesko är på god väg till det som anses viktigt inom konceptet, men att framtiden ställer stora krav på centrallagret och dess kapacitet. De sex gap som identifierades mellan den ideala och nuvarande utformningen och som ansågs påverka kapaciteten på centrallagret var 1) Användandet av cross-docking, 2) E-handelslagrets lokalisering och transportupplägg, 3) Förädlingsstrukturen, 4) Varumärket K-Byggs sortiment på centrallagret, 5) Varumärket Onninens sortiment på centrallagret och 6) Användandet av extern part för säsongslagring. Utifrån dessa gap formulerades åtta stycken förändringsförslag för hur Kesko kan minimera dessa gap och i och med detta gå mot den mer ideala utformningen. Förslagen visade att centrallagret, för att kunna fungera som en resursbas för Kesko i framtiden, troligen behöver en utökning av antalet pallplatser och plockautomatsplatser, en utökning av antalet in- och utlastningsportar samt utlastningsyta. Genom dessa förändringar förväntas centrallagret bli bättre anpassat för att serva de nuvarande varumärkena inom koncernen men även vara bättre förberett för att serva framtida nyförvärv. / In a business environment which is becoming more and more globalized and with continually increasing customer requirements, companies are dealing with flexibility challenges. Customers want short lead times, a lot of customization and excellent service, everything while keeping prices low. Another dimension of complexity is added when large company groups make acquisitions of smaller companies, which means that the company group must ensure that these new acquisitions also can meet the customer's requirements to the same extent.  A solution to this problem can be found in the literature as the concept of a logistics platform. The concept describes a company working with a centralized resource base that serves all parts of the company at a decentralized level in order to meet the customer's requirements. Five building blocks of a logistics platform are central control, logistics concepts, physical structure, logistics processes and activities, and information systems (Abrahamsson, et al., 2003)  This study describes Kesko Sverige, which is a company primarily active in the construction and technical trade, with the brands K-Bygg, K-Rauta, Onninen and Mark & Infra. The problems described above are also found within Kesko, especially regarding acquisitions and the capacity of the central warehouse, which is a warehouse that serves all brands in Kesko Sverige. Therefore, the purpose of this study is to investigate how Kesko can use a logistics platform to serve the various brands and what the use is for the central warehouse in Pilängen.  The study primarily focuses on the logistical concepts and the physical structures within Kesko. The logistics concepts have been restricted to deal with the distribution concepts warehousing, continuous replenishment, vendor managed inventory, cross-docking and direct deliveries, and the physical structure has been restricted to handle location strategy, inventory strategy and transport strategy.  Based on Kesko's customer, supplier and product characteristics, the requirements for the logistics platform are discovered. Based on these characteristics and requirements, an ideal picture of Kesko's logistics platform in the form of distribution concepts and the physical structure is investigated. It is then investigated how Kesko currently is applying the distribution concepts and the physical structure. These two versions, the ideal state and the current state, are then compared in a so-called gap analysis where differences are investigated to discover where there are areas for improvement for Kesko to be considered working towards the concept of a logistics platform.  The analysis shows that Kesko is well on its way to what is considered important in the concept, but that the future places great demand on the central warehouse and its capacity. The 6 gaps that were identified between the ideal and current state and which were considered to affect the capacity of the central warehouse were 1) The use of cross-docking, 2) The e-commerce location and transport arrangements, 3) The physical structure for value-adding services, 4) K-Bygg's assortment at the central warehouse, 5) Onninen's assortment at the central warehouse and 6) The use of external part for seasonal storage. Based on these gaps, eight proposals were formulated regarding how Kesko can minimize these gaps and hence move towards the ideal state. The proposals showed that the central warehouse, in order to work as a resource base for Kesko in the future, probably needs an increase in the number of pallets and places in the automated picking machine, as well as an increased number of loading and unloading ports and an expansion of the unloading area. By making these changes the central warehouse will be better at serving the current brands and the warehouse will also be better prepared to serve future acquisitions.

The main problem with air freight handling at Arlanda is the transportation of freight on airside, that is from the freight terminal to loading process at the aircraft. To approach this problem, a mapping of the physical flow as well as information flow has been made to identify underlying reasons to this problem. This has been the purpose of the study.The mapping has also facilitated the possibilities to identify improvements in the air freight handling process. To give a recommendation of what these improvements could be was the objective of the study.The underlying reasons for the main problem were identified. These causes were space restrictions on the apron, traffic congestion, and lack of freight storage areas by the gates. This aggravates the possibility to prepare freight for each flight departure. The recommendations to Swedavia are long-term measures that should be further explored. These recommendations regard total cost analysis of using fridge containers, co-owned ground handling equipment, IT possibilities,and comparison to other airports.

Freight distribution systems are under stress. With the world population growing, the migration of people to urban areas and technologies that allow purchases from virtually anywhere, efficient freight distribution can be challenging. An inefficient movement of goods may lead to business not being economically viable and also has social and environmental negative effects. An important strategy to be incorporated in freight distribution systems is the consolidation of goods, i.e., group goods by their destination. This strategy increases vehicles utilisation, reducing the number of vehicles and the number of trips required for the distribution and, consequently, costs, traffic, noise and air pollution. In this thesis, we explore consolidation in three different contexts (or cases) from an optimisation point of view. Each context is related to optimisation problems for which we developed mathematical programming models and solution methods. The first case in which we explore consolidation is in container loading problems (CLPs). CLPs are a class of packing problems which aims at positioning three-dimensional boxes inside a container efficiently. The literature has incorporated many practical aspects into container loading solution method (e.g. restricting orientation of boxes, stability and weight distribution). However, to the best of our knowledge, the case considering more dynamic systems (e.g. cross-docking) in which goods might have a schedule of arrival were yet to be contemplated by the literature. We define an extension of CLP which we call Container Loading Problem with Time Availability Constraints (CLPTAC), which considers boxes are not always available for loading. We propose an extension of a CLP model that is suitable for CLPTAC and solution methods which can also handle cases with uncertainty in the schedule of the arrival of the boxes. The second case is a more broad view of the network, considering an open vehicle routing problem with cross-dock selection. The traditional vehicle routing problem has been fairly studied. Its open version (i.e. with routes that start and end at different points) has not received the same attention. We propose a version of the open vehicle routing problem in which some nodes of the network are consolidation centres. Instead of shippers sending goods directly to their consumers, they must send to one of the available consolidation centres, then, goods are resorted and forwarded to their destination. For this problem, we propose a mixed integer linear programming model for cost minimisation and a solution method based on the Benders decomposition framework. A third case in which we explored consolidation is in collaborative logistics. Particularly, we focus on the shared use of the currently available infrastructure. We defined a hub selection problem in which one of the suppliers is selected as a hub. In a hub facility, other suppliers might meet to exchange their goods allowing one supplier to satisfy the demand from others. For this problem, we propose a mixed integer linear programming model and a heuristic based on the model. Moreover, we compared a traditional distribution strategy, with each supplier handling its demand, against the collaborative one. In this thesis, we explore these three cases which are related to consolidation for improving the efficiency in freight distribution systems. We extend some problems (e.g. versions of CLP) to apply them to a more dynamic setting and we also define optimisation problems for networks with consolidation centres. Furthermore, we propose solution methods for each of the defined problems and evaluate them using randomly generated instances, benchmarks from the literature and some cases based on real-world characteristics. / Sistemas de distribuição de carga possuem uma demanda muito alta. Com a população mundial crescendo, a migração em direção às áreas urbanas e as tecnologias que permitem compras de virtualmente qualquer lugar, a distribuição eficiente de mercadorias pode ser um desafio. Uma movimentação ineficiente de mercadorias pode tornar negócios economicamente inviáveis além de ter um impacto social e ambiental negativos. Uma estratégia importante para se incorporar em sistemas de distribuição é a consolidação de cargas, isto é, agrupar cargas de acordo com seus destinos. Essa estratégia aumenta a utilização dos veículos, reduzindo o número de veículos e viagens necessários para a distribuição e, consequentemente, custos, tráfego, poluição sonora e do ar. Nesta tese, é explorada a técnica de consolidação em três casos diferentes de um ponto de vista de otimização. Cada caso é relacionado a problemas de otimização para os quais são propostos modelos de programação matemática e métodos de solução. O primeiro caso em que é explorada a consolidação é em Problemas de Carregamento de Contêineres (PCCs). PCCs pertencem a uma classe de problemas de empacotamento que visa posicionar caixas tridimensionais dentro de contêineres eficientemente. A literatura tem incorporado diversos aspectos práticos em procedimentos de solução dos PCCs (por exemplo, restringir a orientação das caixas, estabilidade e distribuição de peso). No entanto, o caso que considera sistemas logísticos mais dinâmicos (como cross-docking), nos quais mercadorias podem ter uma agenda de chegada ainda não havia sido contemplados. É definida uma extensão de PCC chamada de Problema de Carregamento de Contêieneres com Restrições de Disponibilidade Temporal (PCCRDT). Também, propõem-se modelos e métodos de solução para o PCCRDT que são capazes de lidar com incerteza na chegada das mercadorias. O segundo caso utiliza uma visão mais abrangente da rede de distribuição, considerando um problema de roteamento de veículos em rede aberta com seleção de cross-dock. O problema tradicional de roteamento de veículos é bastante estudado. A sua versão aberta (com rotas que começam e terminam em pontos diferentes) não tem recebido tanta atenção. É proposta uma versão do roteamento de veículos em rede aberta em que alguns nós da rede são centros de consolidação. Os fornecedores, ao invés de enviar as mercadorias diretamente para os consumidores, enviam-nas para um dos centros de consolidação disponíveis, então, as mercadorias são reorganizadas (em diferentes veículos) e encaminhadas para o seus destinos. Para esse problema, é proposto um modelo de programação linear inteira mista para a minimização de custo e um método de solução baseado no arcabouço de decomposição de Benders. Um terceiro caso em que foi explorada a consolidação de mercadorias é o de logística colaborativa. Particularmente, se concentrou no uso compartilhado de infra-estrutura já disponível na rede de distribuição. É definido um problema de seleção de seleção de um dos fornecedores como hub. No hub, outros fornecedores podem se encontrar para trocar suas mercadorias, permitindo que um fornecedor satisfaça a demanda de outro. Para esse problema, é proposto um modelo de programação linear inteira mista e uma heurística baseada no modelo. Ainda, é comparada uma estratégia de distribuição convencional (com cada fornecedor responsável pela sua própria demanda) com uma estratégia colaborativa. Nesta tese, são explorados esses três casos que se relacionam com consolidação para melhorar a eficiência de sistemas de distribuição de carga. São estendidos alguns problemas (como o PCC) para que se possa aplicá-los em cenários mais dinâmicos e também são definidos problemas de otimização em redes com centros de consolidação. Além disso, são propostos métodos de solução para cada um dos casos. Os métodos são avaliados em instâncias geradas aleatoriamente, instâncias da literatura e, em alguns casos, instâncias baseadas em cenários reais.