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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Toward an Understanding of the Built Environment Influences on the Carpool Formation and Use Process: A Case Study of Employer-based Users within the Service Sector of Smart Commute’s Carpool Zone

Bui, Randy 05 December 2011 (has links)
The recent availability of geo-enabled web-based tools creates new possibilities for facilitating carpool formation. Carpool Zone is a web-based carpool formation service offered by Metrolinx, the transportation planning authority for the Greater Toronto and Hamilton Area (GTHA), Canada. The carpooling literature has yet to uncover how different built environments may facilitate or act as barriers to carpool propensity. This research explores the relationship between the built environment and carpool formation. With respect to the built environment, industrial and business parks (homogeneous land-use mix) are associated with high odds of forming carpools. The results suggest that employer transport policies are also among the more salient factors influencing carpool formation and use. Importantly, the findings indicate that firms interested in promoting carpooling will require contingencies to reduce the uncertainty of ride provision that may hamper long-term carpool adoption by employees.
32

Toward an Understanding of the Built Environment Influences on the Carpool Formation and Use Process: A Case Study of Employer-based Users within the Service Sector of Smart Commute’s Carpool Zone

Bui, Randy 05 December 2011 (has links)
The recent availability of geo-enabled web-based tools creates new possibilities for facilitating carpool formation. Carpool Zone is a web-based carpool formation service offered by Metrolinx, the transportation planning authority for the Greater Toronto and Hamilton Area (GTHA), Canada. The carpooling literature has yet to uncover how different built environments may facilitate or act as barriers to carpool propensity. This research explores the relationship between the built environment and carpool formation. With respect to the built environment, industrial and business parks (homogeneous land-use mix) are associated with high odds of forming carpools. The results suggest that employer transport policies are also among the more salient factors influencing carpool formation and use. Importantly, the findings indicate that firms interested in promoting carpooling will require contingencies to reduce the uncertainty of ride provision that may hamper long-term carpool adoption by employees.
33

Extracting airline and passenger behavior from online distribution channels: applications using online pricing and seat map data

Mumbower, Stacey M. 20 September 2013 (has links)
Although the airline industry has drastically changed since its deregulation in 1978, publically available sources of data have remained nearly the same. In the U.S., most researchers and decision-makers rely on government data that contains highly aggregated price information (e.g., average quarterly prices). However, aggregate data can hide important market behavior. With the emergence of online distribution channels, there is a new opportunity to model air travel demand using detailed price information. This dissertation uses online prices and seat maps to build a dataset of daily prices and bookings at the flight-level. Several research contributions are made, all related to leveraging online data to better understand airline pricing and product strategies, and how these strategies impact customers, as well as the industry in general. One major contribution is the finding that the recent product debundling trend in the U.S. airline industry has diluted revenues to the U.S. Airport and Airways Trust Fund by at least five percent. Additionally, several new behavioral insights are found for one debundling trend that has been widely adopted by U.S. airlines: seat reservation fees. Customers are found to be between 2 and 3.3 times more likely to purchase premium coach seats (with extra legroom and early boarding privileges) when there are no regular coach window or aisle seats that can be reserved for free, suggesting that the ability of airlines to charge seat fees is strongly tied to load factors. Model results are used to explore optimal seat fees and find that an optimal static fee could increase revenues by 8 percent, whereas optimal dynamic fees could increase revenues by 10.2 percent. Another major contribution is in modeling daily bookings and estimating price elasticities using ordinary least squares (OLS) regression without correcting for price endogeneity and two-stage least squares (2SLS) regression, which corrects for endogeneity. Results highlight the importance of correcting for price endogeneity (which is not often done in air travel applications). In particular, models that do not correct for endogeneity find inelastic demand estimates whereas models that do correct for endogeneity find elastic demand estimates. This is important, as pricing recommendations differ for inelastic and elastic models. A set of instrumental variables are found to pass validity tests and can be used to correct for price endogeneity in future models of daily flight-level demand.
34

A system-of-systems modeling methodology for strategic general aviation design decision-making

Won, Henry Thome 17 November 2008 (has links)
A methodology for modeling general aviation transportation systems from a system of systems perspective is presented. The completed framework aids the conceptual design process by providing capability-based metrics to the design engineer, as opposed to the traditional performance and cost, system-level metrics. The methodology is applied to two example problems representing promising future general aviation aircraft: the general aviation piston (GAP) and jet (GAJ). Results are presented in an array of formats, and the decision-making strategies that are now apparent in light of the capability-based metrics are described. The findings suggest that the system of systems framework might act as an analytical surrogate to the conventional problem definition process, providing indications of market preferences when that information is not immediately available through the conventional means. Implementation of this methodology can afford engineers a more autonomous perspective in the concept exploration process, providing dynamic feedback about a design's potential success in specific market segments. The method also has potential to strengthen the connection between design and business departments, as well as between manufacturers, service providers, and infrastructure planners - bringing information about how the respective systems interact, and what might be done to improve synergism of systems.
35

An integrative assessment of the commercial air transportation system via adaptive agents

Lim, Choon Giap 17 November 2008 (has links)
The overarching research objective is to address the tightly-coupled interactions between the demand-side and supply-side components of the United States Commercial Air Transportation System (CATS) in a time-variant environment. A system-of-system perspective is adopted, where the scope is extended beyond the National Airspace System (NAS) level to the National Transportation System (NTS) level to capture the intermodal and multimodal relationships between NTS stakeholders. The Agent-Based Modeling and Simulation technique is employed where the NTS/NAS is treated as an integrated Multi-Agent System comprising of consumer and service provider agents representing the demand-side and supply-side components respectively. Successful calibration and validation of both model components against the observable real world data provided a CATS simulation tool where the aviation demand is estimated from socioeconomic and demographic properties of the population instead of merely based on enplanement growth multipliers. This valuable achievement enabled a 20-year outlook simulation study to investigate the implications of a global fuel price hike on the airline industry and the U.S. CATS at large. Simulation outcomes revealed insights into the airline competitive behaviors and the subsequent responses from transportation consumers.
36

A design methodology for evolutionary air transportation networks

Yang, Eunsuk 18 May 2009 (has links)
The air transportation demand at large hubs in the U.S. is anticipated to double in the near future. Current runway construction plans at selected airports can relieve some capacity and delay problems, but many are doubtful that this solution is sufficient to accommodate the anticipated demand growth in the National Airspace System (NAS). With the worsening congestion problem, it is imperative to seek alternative solutions other than costly runway constructions. In this respect, many researchers and organizations have been building models and performing analyses of the NAS. However, the complexity and size of the problem results in an overwhelming task for transportation system modelers. This research seeks to compose an active design algorithm for an evolutionary airline network model so as to include network specific control properties. An airline network designer, referred to as a network architect, can use this tool to assess the possibilities of gaining more capacity by changing the network configuration. Since the Airline Deregulation Act of 1978, the airline service network has evolved from a point-to-point into a distinct hub-and-spoke network. Enplanement demand on the H&S network is the sum of Origin-Destination (O-D) demand and transfer demand. Even though the flight or enplanement demand is a function of O-D demand and passenger routings on the airline network, the distinction between enplanement and O-D demand is not often made. Instead, many demand forecast practices in current days are based on scale-ups from the enplanements, which include the demand to and from transferring network hubs. Based on this research, it was found that the current demand prediction practice can be improved by dissecting enplanements further into smaller pieces of information. As a result, enplanement demand is decomposed into intrinsic and variable parts. The proposed intrinsic demand model is based on the concept of 'true' origin-destination demand which includes the direction of each round trip travel. The result from using true O-D concept reveals the socioeconomic functional roles of airports on the network. Linear trends are observed for both the produced and attracted demand from the data. Therefore, this approach is expected to provide more accurate prediction capability. With the intrinsic demand model in place, the variable part of the demand is modeled on an air transportation network model, which is built with accelerated evolution scheme. The accelerated evolution scheme was introduced to view the air transportation network as an evolutionary one instead of a parametric one. The network model takes in intrinsic demand data before undergoing an evolution path to generate a target network. The results from the network model suggests that air transportation networks can be modeled using evolutionary structure and it was possible to generate the emulated NAS. A dehubbing scenario study of Lambert-St. Louis International Airport demonstrated the prediction capability of the proposed network model. The overall process from intrinsic demand modeling and evolutionary network modeling is a unique and it is highly beneficial for simulating active control of the transportation networks.
37

Análise da evolução da demanda por transportes associada à implantação de estações de metrô. / Analysis of transportation demand evolution associated with deployment of subway stations.

Dionísio Matrigani Mercado Gutierres 25 April 2013 (has links)
Esta dissertação analisa a evolução da demanda por transportes associada à extensão de duas linhas Azul e Verde do Metrô de São Paulo, incluindo cinco estações que iniciaram operação em 1998. A análise usou dados de 1997 e 2007 das Pesquisas Origem e Destino, permitindo a comparação de características de viagem e socioeconômicas. Para cada linha, dois grupos de zonas foram identificadas próximo às novas estações: com impacto direto e com impacto indireto do Metrô. A análise comparou estes grupos geográficos entre eles e temporalmente, usando ambas as Pesquisas OD. Além disso, uma análise desagregada de duas variáveis associadas ao comportamento da demanda por viagem posse de auto e número de viagens foi realizada, objetivando identificar o impacto das novas estações. Os resultados indicam que cada extensão de linha se desenvolveu de forma diferente, em termos de distribuição de atividades e características socioeconômicas. Também, a análise desagregada sugere que o efeito de variáveis como renda familiar e distância até a estação mais próxima pode afetar famílias de forma diferente dependendo da proximidade da zona com o Metrô. / This dissertation analyzes the evolution of transportation demand associated with the extension of two lines Blue and Green of the São Paulo Metro, including five stations that started operating in 1998. The analysis used data from the 1997 and 2007 Origin and Destination Surveys (Pesquisas Origem e Destino), allowing the comparison of travel and socioeconomic characteristics. For each line, two groups of zones were identified in the proximity of the new stations: with direct impact and with indirect impact from the Metrô. The analysis compared these geographic groups between them and in time, using both OD surveys. In addition, a disaggregate analysis of two travel behavior related variables auto ownership and number of trips was conducted, aiming to identify the impact of the new stations. The results indicate that each line extension developed differently, in terms of distribution of activities and socioeconomic characteristics. Also, the disaggregate analysis suggests that the effect of variables such as family income and distance to the nearest station may affect families differently depending on the zone proximity to the Metrô.
38

Estudo da incorporação da acessibilidade à atividade na análise da demanda por viagens encadeadas / Incorporation of accessibility to opportunities on the activity-based travel demand analysis

Mateus Araújo e Silva 25 November 2011 (has links)
O objetivo desta pesquisa é validar a hipótese de que a acessibilidade à oportunidades influencia o comportamento dos padrões de viagens desempenhados pelos indivíduos. Para realizar a verificação desta hipótese foi formulado um procedimento (um teste de hipótese) baseado em um estudo de caso realizado na cidade de Uberlândia, utilizando informações sobre: (i) as características dos deslocamentos dos indivíduos, suas características demográficas e de participação em atividades; (ii) informações sobre o sistema de transportes, e; (iii) informações sobre a distribuição espacial das atividades. Para atingir a finalidade proposta na tese, foram elaborados procedimentos que constituem no processo de verificação da hipótese nula, constituído pelas seguintes etapas: (i) tratamento dos dados; (ii) construção das variáveis (iii) proposta para avaliação da acessibilidade no contexto da formação dos padrões de viagens; (iv) escolha de técnicas de modelagem do comportamento individual referente às decisões sobre padrões de viagens; (v) seleção das técnicas estatísticas para avaliação da significância das variáveis e desempenho dos modelos; (vi) modelagem para simulação do comportamento individual em três níveis de decisão da programação diária de atividades, modo de viagem, destino da atividade primária e padrão de viagens, e; (vii) análise dos resultados obtidos e conclusão sobre a hipótese. Após a realização do experimento realizado com as informações da cidade de Uberlândia, concluiu-se que pela verificação realizada não há elementos para rejeitar a hipótese nula, ou seja, a acessibilidade a oportunidades influencia o comportamento dos padrões de viagens encadeadas desempenhados pelos indivíduos. / The main aim of this work is to submit to a validation test the hypothesis that the accessibility to opportunities influences individuals\' trip chaining behavior. To perform the hypothesis test a procedure was developed on a study case in the city of Uberlandia, using data about: (i) characteristics of the individuals\' trips, their demographic features and activity participation; (ii) transportation system information, and; (iii) information about the spatial distribution of activities. To achieve the purpose of the thesis, it was developed procedures which consist in the hypothesis test, made by the following stages: (i) data processing; (ii) setting of the variables; (iii) a proposal to evaluate the accessibility on the context of trip chaining patterns; (iv) choosing modeling techniques to represent individual behavior regarding to its decisions on trip chaining patterns; (v) selection of statistical techniques for measures of model and variable performance; (vi) modeling individual behavior on three decision levels of the daily activity schedule, mode choice, destination choice and trip chaining patterns, and; (vii) discussion of the results and conclusion about the hypothesis. The main conclusion is that the hypothesis cannot be rejected, i.e., accessibility to opportunities influences individuals\' trip chaining behavior.
39

Análise de ferramentas computacionais para planejamento estratégico do uso do solo e transportes / Analysis of computer tools for strategic land use-transport planning

Rocha, Gustavo Rennó 14 October 2010 (has links)
A constante ausência de planejamento urbano nos países em desenvolvimento é um dos principais fatores responsáveis pela ineficiência da infraestrutura pública de suas cidades, o que é agravado pelo fato de que muitas dessas cidades permanecem em processo de crescimento. Essa falta de planejamento gera inúmeros problemas, principalmente com relação à mobilidade e ao transporte, que por sua vez desencadeiam uma série de outros problemas. Dentre as principais limitações do planejamento sob tais condições, destaca-se a falta de ferramentas apropriadas. Propõe-se assim a caracterização de um modelo para o planejamento estratégico do uso do solo e transportes, com o qual é realizada uma aplicação na cidade de São Carlos, utilizando dados e ferramentas disponíveis. Dessa forma, são analisados os procedimentos executados tanto do ponto de vista técnico do planejamento, quanto do ponto de vista operacional das ferramentas e programas utilizados. Com isso, busca-se construir uma base referencial no sentido de auxiliar o uso, adaptação e desenvolvimento de ferramentas computacionais de planejamento urbano, principalmente para aplicações em cidades médias de países em desenvolvimento e com enfoque no transporte por ônibus. Baseando-se nas principais técnicas de planejamento compatíveis com essa abordagem, o modelo foi definido através de etapas sequenciais, desde a preparação dos dados reunidos, a projeção geográfica de futuros usos do solo, até a previsão e visualização da demanda por transporte urbano. Desse modo, utilizando apenas dados de fácil obtenção, como as informações do Plano Diretor, dados censitários e levantamentos de outras fontes confiáveis, é possível avaliar o impacto do crescimento urbano sobre o sistema de transportes. Para executar o modelo, fez-se uso dos programas What if? e TransCAD, trabalhando os dados através de seus Sistemas de Informações Geográficas e com o eventual auxílio de planilhas eletrônicas. Através da aplicação, o modelo produziu dois cenários distintos, representando diferentes padrões de ocupação e viagem, de acordo com as respectivas hipóteses consideradas. A grande diferença entre os resultados obtidos em cada cenário pode ser explicada principalmente pela falta de políticas de incentivo e controle da ocupação do solo. Entretanto, ambos os cenários apresentaram resultados semelhantes em alguns pontos da cidade, representando tendências bastante prováveis para os próximos anos. As ferramentas e procedimentos utilizados mostraram um bom desempenho do modelo, apesar de eventuais detalhes que podem ser aprimorados. / The absence of a regular urban planning practice in developing countries is one of the main causes of an inefficient use of the public infrastructures. That is aggravated by the fact that many cities of those countries are still growing. That lack of planning generates many mobility and transportation issues, which in turn result in many other problems. One of the constraints faced by planners to cope with that reality is the unavailability of suitable planning tools. As a consequence, a model for strategic land use-transport planning is proposed in this study. The model is then applied in the city of São Carlos, making use of available data and tools. The procedures applied are analyzed in two ways: from a planning standpoint and also regarding the operational performance of the planning tools and computer packages used. The purpose of the process was to build a reference framework for the use, adaptation and development of computer tools for urban planning, with a clear focus on medium-sized cities of developing countries that rely on buses for urban public transportation. The model was based on available and intensely used planning techniques compatible with the proposed approach. It was defined in sequential steps, from the data collection and treatment, the estimation and spatial distribution of projected urban land uses, to the evaluation and visualization of future urban transport demand. In such a way, it is possible to evaluate the impacts of urban growth on the transport system with data available in the city\'s Master Plan, census data files and other reliable sources. As the model was implemented in the computer programs What if? and TransCAD, the data used was treated in Geographic Information Systems and electronic spreadsheets. The model application produced two distinct scenarios, which represent different land use distributions and travel patterns resulting from the adopted hypotheses. The main difference found in the results obtained in the scenarios can be explained by the lack of policies for incentive and control of the urban land uses. However, both scenarios have shown similar results in specific points of the city, what suggests some likely trends for the near future. The tools and procedures used have indicated a good overall model performance, although there are details in which improvements can be done.
40

Aplicação de um modelo baseado em atividades para análise da relação uso do solo e transportes no contexto brasileiro / Analysis of the land use-transportation relationship with an activity-based model in the context of Brazil

Arruda, Fabiana Serra de 14 April 2005 (has links)
Esta tese está voltada para dois temas que vêm sendo, embora raramente juntos, objeto de freqüentes estudos por pesquisadores de todo o mundo: os modelos baseados em atividades para análise da demanda por transportes, e as complexas inter-relações entre características do uso do solo e transportes. De forma geral, o objetivo principal deste estudo é, a partir da aplicação de um modelo baseado em atividades, caracterizar a influência das características do uso do solo nas decisões individuais sobre quais atividades e viagens realizar. O esforço para tal estudo se justifica por alguns motivos. Primeiro, pelo fato da modelagem baseada em atividades ser apontada como metodologia promissora na análise de demanda por transportes, o que conduz à expectativa de que a mesma seja capaz de fornecer resultados que permitam alcançar o objetivo principal desta tese. Segundo, por não existirem, até os dias de hoje, registros de aplicação dessa nova metodologia em cidades brasileiras, este estudo irá permitir que alguns objetivos secundários sejam alcançados. São eles: verificar tanto a viabilidade de aplicação dessa metodologia nas cidades brasileiras de médio porte, bem como buscar a metodologia mais adequada para a coleta dos dados necessários para a calibração desses modelos. Este estudo exploratório torna possível ainda a divulgação no meio acadêmico de uma experiência do uso desses modelos no contexto brasileiro, o que poderá auxiliar e incentivar outros pesquisadores a desenvolverem novos estudos sobre o tema. Em termos concretos, esta pesquisa tornou possível identificar os custos e dificuldades associados à coleta de dados, bem como avaliar o desempenho do modelo, tanto em termos gerais, como em relação aos resultados direcionados para o objetivo geral proposto. No tocante a este último aspecto, os resultados do modelo não permitiram a realização de análises conclusivas sobre a inter-relação uso do solo e transportes, ao que tudo indica em virtude da quantidade de dados coletados não sido suficiente para caracterizar as variáveis de uso do solo de modo claro. Ainda assim, esta tese cumpre um importante papel do ponto de vista acadêmico, na medida em que inova nos campos conceitual, metodológico e tecnológico, além de servir como guia e incentivo para que outros pesquisadores aprofundem o estudo dos modelos baseados em atividades para modelagem da demanda por transportes / This study is directed to two themes that frequently are, although rarely together, the subject of research projects in many parts of the world: the use of activity based models for the analysis of transportation demand and the complex relationships among land use characteristics and transportation. The main aim of this work is to verify the influence of land use characteristics on individual activities and travel decisions, by means of an activity based model. The motivation for it comes from two aspects. First, activity based models are pointed by many authors as the most promising approach currently available for transportation demand analysis. As a consequence, it may be able to produce results that contribute for reaching the main objective of this study. Second, given that the search in the literature has shown no records of activity-based models applied to brazilian cities, this study also contributes to the some secondary objectives, as follows. It helps to test the viability of the modeling approach in Brazilian medium-sized cities and it is also useful for seeking the most appropriate method for the collection of data needed for model calibration. In addition, exploratory studies such as this one are important to disseminate the possibilities offered by the models in the brazilian context, what can encourage other researchers to direct efforts to the topic. In concrete terms, the application carried out in this investigation made possible not only to identify the costs and difficulties associated to data collection, but also to evaluate the model performance. Its performance was assessed in two ways: in general terms, and concerning the results specifically associated with the main objective of the study. With regard to the latter, the model results did not allow conclusive analyses about the land use-transportation relationship, apparently because the data sample was not comprehensive enough to clearly characterize land use variables. Even though, this investigation plays an important role from an academic standpoint, given that it brings innovation to the country in conceptual, methodological, and technological fields. As a consequence, its main merit is certainly to serve as a guide and an incentive to other brazilian researchers interested in the development of new studies about activity based models and their application to transportation demand modeling

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