OPTIMIZATION OF RAILWAY TRANSPORTATION HAZMATS AND REGULAR COMMODITIES

Transportation of dangerous goods has been receiving more attention in the realm of academic and scientific research during the last few decades as countries have been increasingly becoming industrialized throughout the world, thereby making Hazmats an integral part of our life style. However, the number of scholarly articles in this field is not as many as those of other areas in SCM. Considering the low-probability-and-high-consequence (LPHC) essence of transportation of Hazmats, on the one hand, and immense volume of shipments accounting for more than hundred tons in North America and Europe, on the other, we can safely state that the number of scholarly articles and dissertations have not been proportional to the significance of the subject of interest. On this ground, we conducted our research to contribute towards further developing the domain of Hazmats transportation, and sustainable supply chain management (SSCM), in general terms. Transportation of Hazmats, from logistical standpoint, may include all modes of transport via air, marine, road and rail, as well as intermodal transportation systems. Although road shipment is predominant in most of the literature, railway transportation of Hazmats has proven to be a potentially significant means of transporting dangerous goods with respect to both economies of scale and risk of transportation; these factors, have not just given rise to more thoroughly investigation of intermodal transportation of Hazmats using road and rail networks, but has encouraged the competition between rail and road companies which may indeed have some inherent advantages compared to the other medium due to their infrastructural and technological backgrounds. Truck shipment has ostensibly proven to be providing more flexibility; trains, per contra, provide more reliability in terms of transport risk for conveying Hazmats in bulks. In this thesis, in consonance with the aforementioned motivation, we provide an introduction into the hazardous commodities shipment through rail network in the first chapter of the thesis. Providing relevant statistics on the volume of Hazmat goods, number of accidents, rate of incidents, and rate of fatalities and injuries due to the incidents involving Hazmats, will shed light onto the significance of the topic under study. As well, we review the most pertinent articles while putting more emphasis on the state-of-the-art papers, in chapter two. Following the discussion in chapter 3 and looking at the problem from carrier company’s perspective, a mixed integer quadratically constraint problem (MIQCP) is developed which seeks for the minimization of transportation cost under a set of constraints including those associating with Hazmats. Due to the complexity of the problem, the risk function has been piecewise linearized using a set of auxiliary variables, thereby resulting in an MIP problem. Further, considering the interests of both carrier companies and regulatory agencies, which are minimization of cost and risk, respectively, a multiobjective MINLP model is developed, which has been reduced to an MILP through piecewise linearization of the risk term in the objective function. For both single-objective and multiobjective formulations, model variants with bifurcated and nonbifurcated flows have been presented. Then, in chapter 4, we carry out experiments considering two main cases where the first case presents smaller instances of the problem and the second case focuses on a larger instance of the problem. Eventually, in chapter five, we conclude the dissertation with a summary of the overall discussion as well as presenting some comments on avenues of future work

The hazardous waste location-routing problem

Cataloged from PDF version of article.As a result of high industrialization and technology hazardous waste management problem has now become an unavoidable problem of the world. Hazardous waste management involves collection, transportation, treatment and disposal of hazardous wastes. In this thesis, the existing models in the literature are analyzed in terms of applicability. A new multiobjective location-routing model is proposed by combining the applicable aspects from different models. Our model also includes the constraints that reflect certain requirements that have been observed in the literature but could not been incorporated into the models correctly together with the additional constraints that we propose. The aim of the model is to decide on the following questions: where to open treatment centers with which technologies, where to open disposal centers, how to route different types of hazardous wastes to which of the compatible treatment technologies, and how to route waste residues to disposal centers. The model has two objectives of minimizing total cost and minimizing transportation risk. A large scale implementation of the model in the Central Anatolian Region of Turkey is presented.Alumur, SibelM.S

Problemas de localização-distribuição de serviços semiobnóxios: aproximações e apoio à decisão

Doutoramento em Gestão IndustrialA presente tese resulta de um trabalho de investigação cujo objectivo se centrou no problema de localização-distribuição (PLD) que pretende abordar, de forma integrada, duas actividades logísticas intimamente relacionadas: a localização de equipamentos e a distribuição de produtos. O PLD, nomeadamente a sua modelação matemática, tem sido estudado na literatura, dando origem a diversas aproximações que resultam de diferentes cenários reais. Importa portanto agrupar as diferentes variantes por forma a facilitar e potenciar a sua investigação. Após fazer uma revisão e propor uma taxonomia dos modelos de localização-distribuição, este trabalho foca-se na resolução de alguns modelos considerados como mais representativos. É feita assim a análise de dois dos PLDs mais básicos (os problema capacitados com procura nos nós e nos arcos), sendo apresentadas, para ambos, propostas de resolução. Posteriormente, é abordada a localização-distribuição de serviços semiobnóxios. Este tipo de serviços, ainda que seja necessário e indispensável para o público em geral, dada a sua natureza, exerce um efeito desagradável sobre as comunidades contíguas. Assim, aos critérios tipicamente utilizados na tomada de decisão sobre a localização destes serviços (habitualmente a minimização de custo) é necessário adicionar preocupações que reflectem a manutenção da qualidade de vida das regiões que sofrem o impacto do resultado da referida decisão. A abordagem da localização-distribuição de serviços semiobnóxios requer portanto uma análise multi-objectivo. Esta análise pode ser feita com recurso a dois métodos distintos: não interactivos e interactivos. Ambos são abordados nesta tese, com novas propostas, sendo o método interactivo proposto aplicável a outros problemas de programação inteira mista multi-objectivo. Por último, é desenvolvida uma ferramenta de apoio à decisão para os problemas abordados nesta tese, sendo apresentada a metodologia adoptada e as suas principais funcionalidades. A ferramenta desenvolvida tem grandes preocupações com a interface de utilizador, visto ser direccionada para decisores que tipicamente não têm conhecimentos sobre os modelos matemáticos subjacentes a este tipo de problemas.This thesis main objective is to address the location-routing problem (LRP) which intends to tackle, using an integrated approach, two highly related logistics activities: the location of facilities and the distribution of materials. The LRP, namely its mathematical formulation, has been studied in the literature, and several approaches have emerged, corresponding to different real-world scenarios. Therefore, it is important to identify and group the different LRP variants, in order to segment current research and foster future studies. After presenting a review and a taxonomy of location-routing models, the following research focuses on solving some of its variants. Thus, a study of two of the most basic LRPs (capacitated problems with demand either on the nodes or on the arcs) is performed, and new approaches are presented. Afterwards, the location-routing of semi-obnoxious facilities is addressed. These are facilities that, although providing useful and indispensible services, given their nature, bring about an undesirable effect to adjacent communities. Consequently, to the usual objectives when considering their location (cost minimization), new ones must be added that are able to reflect concerns regarding the quality of life of the communities impacted by the outcome of these decisions. The location-routing of semi-obnoxious facilities therefore requires to be analysed using multi-objective approaches, which can be of two types: noninteractive or interactive. Both are discussed and new methods proposed in this thesis; the proposed interactive method is suitable to other multi-objective mixed integer programming problems. Finally, a newly developed decision-support tool to address the LRP is presented (being the adopted methodology discussed, and its main functionalities shown). This tool has great concerns regarding the user interface, as it is directed at decision makers who typically don’t have specific knowledge of the underlying models of this type of problems

A concise guide to existing and emerging vehicle routing problem variants

Vehicle routing problems have been the focus of extensive research over the past sixty years, driven by their economic importance and their theoretical interest. The diversity of applications has motivated the study of a myriad of problem variants with different attributes. In this article, we provide a concise overview of existing and emerging problem variants. Models are typically refined along three lines: considering more relevant objectives and performance metrics, integrating vehicle routing evaluations with other tactical decisions, and capturing fine-grained yet essential aspects of modern supply chains. We organize the main problem attributes within this structured framework. We discuss recent research directions and pinpoint current shortcomings, recent successes, and emerging challenges

Fairness in hazmat routing-scheduling: a bi-objective Stackelberg game

We investigate a hazmat routing-scheduling problem. To minimize the overall expected risk, various vehicles may take different routes/schedules to avoid multiple accidents on the same link. Therefore, the company envisages two issues: (1) unfairly, a vehicle departing earlier from its origin may arrive earlier at its destination than the others leaving later; (2) focusing only on the minimization of risk may increase travel time/cost incurred by the company. We suggest a bi-objective game-theoretic formulation and solve it by a modified Adaptive Large Neighborhood Search and Simulated Annealing. We test the solution on a real-life case and extract practical insights

Vehicle routing for hazardous material transportation

The main objective of this thesis is to study the hazardous materials (HazMat) transportation problem considered as a heterogeneous fleet vehicle routing problem. HazMat transportation decisions comprise different and sometimes conflicting objectives. Two are considered in this work, the total routing cost and the total routing risk. The first task undertaken was the formulation of a mathematical model for the routing risk minimization, which depends on the type of vehicle, the material being transported, and the load change when the vehicle goes from one customer to another. A piecewise linear approximation is employed to keep a mixed integer linear programing formulation. Hybrid solution methods based on neighborhood search are explored for solving the routing risk minimization. This includes the study of neighborhood structures and the development of a Variable Neighborhood Descent (VND) algorithm for local search, and a perturbation mechanism (shaking neighborhoods). A postoptimization procedure is applied to improve the solution quality. Finally, two different solution approaches, a multi-objective dominance-based algorithm and a meta-heuristic ϵ-constraint method are employed for addressing the multi-objective version of the problem. Two performance metrics are used: the hypervolume and the ∆-metric. The front approximations show that a small increment in the total routing cost can produce a high reduction in percentage of the expected consequences given the probability of a HazMat transportation incident.Résumé: L’objectif de cette thèse est d’étudier le problème du transport de matiêres dan- ` gereuses (HazMat) vu comme un probleme de tournées de véhicules à flotte hétèrogène. Les dècisions pour ce type de transport comportent des objectifs différents, parfois antagonistes. Deux sont pris en compte dans ce travail, le coût et le risque. La première tâche entreprise a été la formulation d’un modèle mathématique pour la minimisation du risque, qui depend du type de véhicule, du matériel transporté et du changement de charge lorsque le véhicule passe d’un client à un autre. Une approximation linéaire par morceaux est utilisée pour conserver une formulation de programmation linéaire en nombres entiers mixtes. Des méthodes hybrides basées sur des explorations de voisinages sont proposées pour traiter la minimisation du risque. Cela comprend l’étude des structures de voisinages et le développement d’un algorithme de descente à voisinages variables (VND) pour la recherche locale, ainsi qu’un mécanisme de perturbation des solutions. Une post-optimisation est appliquée pour améliorer la qualité des solutions obtenues. Enfin, deux approches, un algorithme base sur la dominance multi-objectif et une méta-heuristique de type ϵ- contrainte, sont développes pour traiter la version multi-objectif. Deux mesures de performance sont utilisées : l’hypervolume et la ∆-metrique. Les approximations de fronts montrent qu’une légère augmentation du coût total des tournées peut entraîner une forte réduction en pourcentage des risques.Resumen: El objetivo principal de esta tesis es estudiar el problema del transporte de materiales peligrosos (HazMat hazardous materials) modelado como un problema de ruteo de vehículos con flota heterogénea (HVRP ´ heterogeneous fleet vehicle routing problem). Las decisiones en el transporte de HazMat comprenden considerar objetivos diferentes y a veces contradictorios. Dos son los objetivos considerados en este trabajo, el costo y el riesgo total de ruteo. La primera tarea realizada fue la formulación de un modelo matemático para la minimización del riesgo de ruteo, que depende del tipo de vehículo, el material que se transporta y el cambio en el tamaño de la carga cuando el vehículo pasa de un cliente a otro. Se emplea una aproximación lineal por partes de la función objetivo para mantener una formulación de programación lineal entera mixta. Se exploran métodos híbridos de solución basados en búsqueda por vecindarios para resolver el problema de minimización del riesgo total de ruteo. Esto incluye el estudio de las estructuras del vecindario y el desarrollo de un algoritmo de descenso de vecindario variable (VND variable neighborhood descent) para realizar la búsqueda local, y de mecanismos de perturbación (estructuras de vecindario para perturbar las soluciones). Se aplica un procedimiento post-optimización (SP set partitioning) para mejorar la calidad de las soluciones. Finalmente, se emplean dos enfoques de solución diferentes para abordar la versión multi-objetivo del problema, un algoritmo basado en la dominancia Pareto y un método ϵ-constraint heurísticos. Se utilizan dos indicadores de rendimiento para algoritmos multiobjetivo: el hypervolumen y la métrica ∆. Las aproximaciones del frente Pareto obtenidas muestran que un pequeño incremento en el costo total de ruteo puede producir una gran reducción en el porcentaje de las consecuencias esperadas dada la probabilidad de un incidente de transporte de materiales peligrosos.Doctorad