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

Simulation and optimization of a multi-agent system on physical internet enabled interconnected urban logistics.

An urban logistics system is composed of multiple agents, e.g., shippers, carriers, and distribution centers, etc., and multi-modal networks. The structure of Physical Internet (PI) transportation network is different from current logistics practices, and simulation can effectively model a series of PI-approach scenarios. In addition to the baseline model, three more scenarios are enacted based on different characteristics: shared trucks, shared hubs, and shared flows with other less-than-truckload shipments passing through the urban area. Five performance measures, i.e., truck distance per container, mean truck time per container, lead time, CO2 emissions, and transport mean fill rate, are included in the proposed procedures using real data in an urban logistics case. The results show that PI enables a significant improvement of urban transportation efficiency and sustainability. Specifically, truck time per container reduces 26 percent from that of the Private Direct scenario. A 42 percent reduction of CO2 emissions is made from the current logistics practice. The fill rate of truckload is increased by almost 33 percent, whereas the relevant longer distance per container and the lead time has been increased by an acceptable range. Next, the dissertation applies an auction mechanism in the PI network. Within the auction-based transportation planning approach, a model is developed to match the requests and the transport services in transport marketplaces and maximize the carriers’ revenue. In such transportation planning under the protocol of PI, it is a critical system design problem for decision makers to understand how various parameters through interactions affect this multi-agent system. This study provides a comprehensive three-layer structure model, i.e. agent-based simulation, auction mechanism, and optimization via simulation. In term of simulation, a multi-agent model simulates a complex PI transportation network in the context of sharing economy. Then, an auction mechanism structure is developed to demonstrate a transport selection scheme. With regard of an optimization via simulation approach and sensitivity analysis, it has been provided with insights on effects of combination of decision variables (i.e. truck number and truck capacity) and parameters settings, where results can be drawn by using a case study in an urban freight transportation network. In the end, conclusions and discussions of the studies have been summarized. Additionally, some relevant areas are required for further elaborate research, e.g., operational research on airport gate assignment problems and the simulation modelling of air cargo transportation networks. Due to the complexity of integration with models, I relegate those for future independent research

OPTIMIZATION MODELS AND METHODOLOGIES TO SUPPORT EMERGENCY PREPAREDNESS AND POST-DISASTER RESPONSE

This dissertation addresses three important optimization problems arising during the phases of pre-disaster emergency preparedness and post-disaster response in time-dependent, stochastic and dynamic environments. The first problem studied is the building evacuation problem with shared information (BEPSI), which seeks a set of evacuation routes and the assignment of evacuees to these routes with the minimum total evacuation time. The BEPSI incorporates the constraints of shared information in providing on-line instructions to evacuees and ensures that evacuees departing from an intermediate or source location at a mutual point in time receive common instructions. A mixed-integer linear program is formulated for the BEPSI and an exact technique based on Benders decomposition is proposed for its solution. Numerical experiments conducted on a mid-sized real-world example demonstrate the effectiveness of the proposed algorithm. The second problem addressed is the network resilience problem (NRP), involving an indicator of network resilience proposed to quantify the ability of a network to recover from randomly arising disruptions resulting from a disaster event. A stochastic, mixed integer program is proposed for quantifying network resilience and identifying the optimal post-event course of action to take. A solution technique based on concepts of Benders decomposition, column generation and Monte Carlo simulation is proposed. Experiments were conducted to illustrate the resilience concept and procedure for its measurement, and to assess the role of network topology in its magnitude. The last problem addressed is the urban search and rescue team deployment problem (USAR-TDP). The USAR-TDP seeks an optimal deployment of USAR teams to disaster sites, including the order of site visits, with the ultimate goal of maximizing the expected number of saved lives over the search and rescue period. A multistage stochastic program is proposed to capture problem uncertainty and dynamics. The solution technique involves the solution of a sequence of interrelated two-stage stochastic programs with recourse. A column generation-based technique is proposed for the solution of each problem instance arising as the start of each decision epoch over a time horizon. Numerical experiments conducted on an example of the 2010 Haiti earthquake are presented to illustrate the effectiveness of the proposed approach

Hybrid modeling of collaborative freight transportation planning using agent-based simulation, auction-based mechanisms, and optimization

This is the author accepted manuscript. The final version is available from SAGE Publications via the DOI in this recordThe sharing economy is a peer-to-peer economic model characterized by people and organizations sharing resources. With the emergence of such economies, an increasing number of logistics providers seek to collaborate and derive benefit from the resultant economic efficiencies, sustainable operations, and network resilience. This study investigates the potential for collaborative planning enabled through a Physical Internet-enabled logistics system in an urban area that acts as a freight transport hub with several e-commerce warehouses. Our collaborative freight transportation planning approach is realized through a three-layer structured hybrid model that includes agent-based simulation, auction mechanism, and optimization. A multi-agent model simulates a complex transportation network, an auction mechanism facilitates allocating transport services to freight requests, and a simulation–optimization technique is used to analyze strategic transportation planning under different objectives. Furthermore, sensitivity analyses and Pareto efficiency experiments are conducted to draw insights regarding the effect of parameter settings and multi-objectives. The computational results demonstrate the efficacy of our developed model and solution approach, tested on a real urban freight transportation network in a major US city

Fallas del estado, violencia y comercio: rutas comerciales peligrosas en Colombia

En este documento se investiga el efecto de la violencia armada doméstica provocada por la inestabilidad política sobre las fricciones de la distancia en la movilidad de carga. Además, el efecto de esas fricciones sobre el acceso diferencial de las regiones a los mercados globales. Se concluye que el sistema de transporte colombiano se ve obstaculizado por deficiencias en la infraestructura e instituciones de transporte terrestre y por entornos políticos fragmentados. El análisis a nivel micro de los registros de exportaciones hacia Estados Unidos corrobora que el envío de carga de exportación desde las regiones del interior se redirige para evitar exposiciones a la violencia armada doméstica a pesar de las amplias distancias de envío marítimo y terrestre existentes. Aprovechamos las trayectorias del transporte de carga desde las regiones colombianas y los patrones espaciales de los conflictos armados violentos para ver cómo los entornos geopolíticos inestables son perjudiciales para la movilidad del transporte de carga y la apertura del mercado. A través de un modelo de elección discreta se muestra que el flujo de envío se ve frenado por el desvío debido a la violencia armada doméstica y que las regiones del interior tienen acceso restringido al mercado global. La percepción de riesgo y comportamiento de redireccionamiento se considera heterogénea entre los envíos y está condicionada a las características del envío, como el tipo de mercancía, el tamaño y el valor del flete. Los resultados resaltan que el conseguir la estabilidad política puede ayudar a mejorar la movilidad de carga y el desarrollo económico orientado a la exportación en el Sur globalWe investigate the effect of domestic armed violence brought about by political instability on the geography of distance frictions in freight mobility and the resulting differential access of regions to global markets. The Colombian transportation system has been found to be impeded by deficiencies in landside transport infrastructure and institutions, and by fragmented political environments. The micro-level analysis of U.S.-bounded export shipping records corroborates that export freight shipping from inland regions is re-routed to avoid exposures to domestic armed violence despite greatly extended landside and maritime shipping distances. We exploit the trajectories of freight shipping from Colombian regions and spatial patterns of violent armed conflicts to see how unstable geopolitical environments are detrimental to freight shipping mobility and market openness. The discrete choice model shows that the shipping flow is greatly curbed by the extended re-routing due to domestic armed violence and that inland regions have restricted access to the global market. The perception of risk and re-routing behavior is found heterogeneous across shipments and conditional to shipment characteristics, such as commodity type, freight value and shipper sizes. The results highlight that political stability must be accommodated for improved freight mobility and export-oriented economic development in the global South.Fallas del estado, violencia y comercio: Rutas comerciales peligrosas en Colombia Enfoque En este artículo se investiga cómo el efecto la violencia armada, que surge en medio de entornos geopolíticos inestables, es perjudicial para la movilidad de carga y el acceso de las regiones a las cadenas globales de logística de mercancías. Nuestro análisis se centra en el caso de Colombia en 2006-2007, por ser un periodo que estuvo muy permeado por la violencia y delincuencia, en muchas de las rutas principales de transporte al interior del país. El objetivo es determinar cómo la inseguridad durante este período de tiempo actuó como un impedimento para el movimiento del transporte marítimo de carga en el comercio internacional, actuando como otros de sus determinantes, tales como los factores arancelarios y no arancelarios. De esta manera, se propone la hipótesis de que los encargados de la logística del transporte buscarían reducir su exposición a conflictos armados domésticos a lo largo de las rutas, desplazándose a puertos más lejanos, a los que se pueda acceder de manera más segura, pese a tener que opotar por distancias de envío más extendidas. Para este efecto, este trabajo explota la existencia de registros de embarque proveniente de las bases de datos de Port Import Export Reporting Services y los datos georreferenciados de conflictos armados nacionales de Uppsala Conflict Data Program. Contribución La visión tradicional en la literatura comercial se ha concentrado en cómo el efecto de los aranceles, las cuotas, el acceso al mar, las fronteras internacionales o la calidad de la infraestructura logística limitan las actividades de exportación y el comercio internacional. Nuestra principal contribución a la discusión está relacionada con los efectos que puede tener la inseguridad como otro impedimento importante para el cruce de fronteras de mercancías. Específicamente, calculamos las equivalencias en distancia del riesgo observado de conflictos armados internos para medir el costo del cambio de ruta y evaluamos hasta qué punto estos restringen el acceso a los mercados globales. Conclusiones Encontramos evidencia sobre Colombia, centrados en el período 2006-2007, de que el riesgo de violencia a lo largo de las rutas de transporte marítimo terrestre resulta en una geografía de la movilidad de carga alterada, con rutas de envío más riesgosas a los puertos que se evitan, en favor de otras opciones más seguras. Los transportistas cambiarían una ruta más corta, pero más riesgosa, por una ruta más segura a puertos ubicados más lejos del origen del envío. Además, estarían dispuestos a tomar la ruta de envío terrestre a puertos donde haya mayor seguridad, incluso en el caso en que el segmento marítimo de la distancia de envío, asociada al puerto de entrada de los Estados Unidos, sea más extenso. Nuestro estudio plantea que la falta de control de la violencia armada a lo largo de las rutas comerciales impide extensamente el transporte de carga, aumenta el costo de hacer negocios y limita en gran medida el acceso al mercado global, lo que podría desalentar las actividades económicas orientadas a la exportación. Frase destacada: Nuestro estudio plantea que la falta de control de la violencia armada a lo largo de las rutas comerciales impide extensamente el transporte de carga, aumenta el costo de hacer negocios y limita el acceso al mercado global, lo que podría desalentar las actividades económicas orientadas a la exportación

Energy and Carbon Dioxide Impacts from Lean Logistics and Retailing Systems: A Discrete-event Simulation Approach for the Consumer Goods Industry

abstract: Consumer goods supply chains have gradually incorporated lean manufacturing principles to identify and reduce non-value-added activities. Companies implementing lean practices have experienced improvements in cost, quality, and demand responsiveness. However certain elements of these practices, especially those related to transportation and distribution may have detrimental impact on the environment. This study asks: What impact do current best practices in lean logistics and retailing have on environmental performance? The research hypothesis of this dissertation establishes that lean distribution of durable and consumable goods can result in an increased amount of carbon dioxide emissions, leading to climate change and natural resource depletion impacts, while lean retailing operations can reduce carbon emissions. Distribution and retailing phases of the life cycle are characterized in a two-echelon supply chain discrete-event simulation modeled after current operations from leading organizations based in the U.S. Southwest. By conducting an overview of critical sustainability issues and their relationship with consumer products, it is possible to address the environmental implications of lean logistics and retailing operations. Provided the waste reduction nature from lean manufacturing, four lean best practices are examined in detail in order to formulate specific research propositions. These propositions are integrated into an experimental design linking annual carbon dioxide equivalent emissions to: (1) shipment frequency between supply chain partners, (2) proximity between decoupling point of products and final customers, (3) inventory turns at the warehousing level, and (4) degree of supplier integration. All propositions are tested through the use of the simulation model. Results confirmed the four research propositions. Furthermore, they suggest synergy between product shipment frequency among supply chain partners and product management due to lean retailing practices. In addition, the study confirms prior research speculations about the potential carbon intensity from transportation operations subject to lean principles.Dissertation/ThesisPh.D. Sustainability 201