xi, 51 p. : ill. (some col.) / Conducting field studies for human centric research often demands a significant amount of time and effort. Virtual Environments (VE) can be a potential alternative to reduce such requirements and help scale the field studies. However, we may experience a performance difference between (1) a virtual trial, and (2) a field trial of the same study. To learn under what circumstances a VE can successfully replace a field study and when it fails, this thesis describes a route-following experiment that compares the participants' performance between a simple VE and a field setup. The experiment results unveil that there is a significant difference in performance between a physical and a virtual setup for more challenging navigational tasks, whereas no significant difference is observed for simpler tasks. This finding encourages us to replace a less challenging field study with a simple VE, and explore the possibilities for a complex one. / Committee in charge: Dr. Stephen Fickas, Chairperson; Dr. Christopher Wilson, Member

Master of Science / Food Science Institute / Valentina Trinetta / Salmonella is an important pathogen of public health concern. Each year, Salmonella costs the food industry approximately $2.3 billion. In recent years, the number of cases of Salmonella linked to pork products has also increased in the United States (US). Although pork has the lowest association with human foodborne illness when compared to beef and chicken, it is the most consumed meat in the world. Therefore, Salmonella is a significant food safety concern for the American swine industry. This pathogen can be present along all the food production chain from farm to fork and recent studies reported the isolation of Salmonella enterica serovar Typhimurium (ST) and its monophasic variant 4,[5],12:i:- (STM) in feed and feed ingredients. The occurrence of these pathogens in the pre-harvest environment can translate to entry and contamination of the human food chain. Nevertheless, little is known about Salmonella incidence and association with these types of environments. Hence, the purpose of this study was to investigate the presence and seasonal prevalence of Salmonella spp., ST and STM in selected feed mills, among the major US swine feed production areas. Eleven swine feed mills in eight different states were selected. Six mills produced only mash feed, while the other five facilities produced both mash and pelleted feed. Visits were conducted during fall 2016, early spring 2017 and summer 2017. Twelve environmental samples were collected within each facility and season, representative of the production flow, from receiving of ingredients to the finished product, including floor surfaces, equipment dust, workers’ shoes, and finished feed. Samples were analyzed following the USDA-FSIS guidelines and culture positive samples were analyzed by PCR. A multiplex PCR assay was also performed to differentiate Salmonella Typhimurium and Salmonella I 4,[5],12:i:- from the other serotypes. Associations between mill, season, mill type, sample site and Salmonella prevalence were analyzed using generalized linear mixed models (P < 0.05). From the 383 samples collected, 49 (12.8%) were identified as Salmonella spp.; two (5.1%) were identified from feed, while the other 47 (13.7%) originated from equipment or surfaces. Two samples were positive for ST and three for STM by multiplex PCR. Mill (P = 0.003) and season (P = 0.006) were statistically associated with the presence of Salmonella, with higher prevalence in fall and summer (13.2%) as compared to spring (3.6%). These findings demonstrate the seasonal prevalence of Salmonella spp., ST and STM in feed mills across the US, highlighting the potential role of the feed mill environment as a microbial entry route into the human food chain. The data presented can be also used as a tool to assist in the implementation of mitigation strategies for pre-harvest food safety.

The design of new facilities - buildings, shopping centers, public transport stations, airports, or intersections of urban roads - should consider delays resulting from intense pedestrians’ flows in order to make its' operation more efficient. The general objective of this doctoral thesis is to propose a simulation model to represent pedestrians’ behavior in urban environments. Simulation models should allow planning these environments in order to provide greater levels of comfort and safety for the pedestrian. Agent-based abstraction has been widely used for pedestrian modeling, mainly due to its capacity to represent complex entities. Agent-based models represent agents’ decision-making ability based on their profile and perception over the environment. One of the most important pedestrians’ activities is the route choice. This document describes the development of a route choice model based on friction forces. The route cost calculation considers a balance between distance and the impedance generated by other pedestrians. Simulations runs shown that pedestrians choosing longer routes can have similar or better travel times. The ability of choosing not only the shorter route brings more realistic behaviors for the pedestrians’ representation, especially with small differences in route lengths and higher congestion. On the proposed model agents were modeled with partial knowledge of the network conditions. The knowledge was limited considering the pedestrian estimated field of view. In the real world it is not possible to know the network state before turning the corner. The model was validated and calibrated with real data. Calibrating a pedestrian route choice model is a complex task mainly for two reasons: (i) Many factors interfere on pedestrians’ route choice; (ii) data collection is difficult. To overcome these difficulties real pedestrians were studied in a controlled environment. An experiment was set up inside the university campus. After the calibration process the model was able to simulate a real scenario. Proposed model was applied to simulate a shopping mall environment. Simulate the pedestrians shopping behavior is particularly complex once route choice in shopping malls may be defined by a number of causal factors. Shoppers may follow a pre-defined schedule; they may be influenced by other people walking, or may want to get a glimpse of a familiar shopping. Analysis from simulations indicates that the agents’ behavior provides a promising approach for real case applications.

Um melhor uso da infraestrutura da rede de transporte é um ponto fundamental para atenuar os efeitos dos congestionamentos no trânsito. Este trabalho utiliza aprendizado por reforço multiagente (MARL) para melhorar o uso da infraestrutura e, consequentemente, mitigar tais congestionamentos. A partir disso, diversos desafios surgem. Primeiro, a maioria da literatura assume que os motoristas aprendem (semáforos não possuem nenhum tipo de aprendizado) ou os semáforos aprendem (motoristas não alteram seus comportamentos). Em segundo lugar, independentemente do tipo de classe de agentes e do tipo de aprendizado, as ações são altamente acopladas, tornando a tarefa de aprendizado mais difícil. Terceiro, quando duas classes de agentes co-aprendem, as tarefas de aprendizado de cada agente são de natureza diferente (do ponto de vista do aprendizado por reforço multiagente). Finalmente, é utilizada uma modelagem microscópica, que modela os agentes com um alto nível de detalhes, o que não é trivial, pois cada agente tem seu próprio ritmo de aprendizado. Portanto, este trabalho não propõe somente a abordagem de co-aprendizado em agentes que atuam em ambiente compartilhado, mas também argumenta que essa tarefa precisa ser formulada de forma assíncrona. Além disso, os agentes motoristas podem atualizar os valores das ações disponíveis ao receber informações de outros motoristas. Os resultados mostram que a abordagem proposta, baseada no coaprendizado, supera outras políticas em termos de tempo médio de viagem. Além disso, quando o co-aprendizado é utilizado, as filas de veículos parados nos semáforos são menores. / A better use of transport network infrastructure is a key point in mitigating the effects of traffic congestion. This work uses multiagent reinforcement learning (MARL) to improve the use of infrastructure and, consequently, to reduce such congestion. From this, several challenges arise. First, most literature assumes that drivers learn (traffic lights do not have any type of learning) or the traffic lights learn (drivers do not change their behaviors). Second, regardless of the type of agent class and the type of learning, the actions are highly coupled, making the learning task more difficult. Third, when two classes of agents co-learn, the learning tasks of each agent are of a different nature (from the point of view of multiagent reinforcement learning). Finally, a microscopic modeling is used, which models the agents with a high level of detail, which is not trivial, since each agent has its own learning pace. Therefore, this work does not only propose the co-learnig approach in agents that act in a shared environment, but also argues that this taks needs to be formulated asynchronously. In addtion, driver agents can update the value of the available actions by receiving information from other drivers. The results show that the proposed approach, based on co-learning, outperforms other policies regarding average travel time. Also, when co-learning is use, queues of stopped vehicles at traffic lights are lower.

La construction et l'utilisation d'une route dépendent de nombreux facteurs politiques. La route alors qu'elle est à l'état de simple ébauche est le fruit de réflexions politiques à plusieurs échelles. En ce qui concerne les routes alpines, de nombreux enjeux sont à prendre en considération. Si son édification s'inscrit dans un contexte national, la route est aussi le fruit de querelles locales. Elle construit des territoires, de nouvelles frontières, de nouveaux espaces. La route crée des inégalités. La route est un symbole de modernité. Elle est le lieu où s'opposent progrès et tradition. Les routes des Alpes sont le théâtre d'une confrontation entre deux modes de pensée, celui des ingénieurs, et celui des sociétés rurales. Si la route ne permet pas toujours le désenclavement des sociétés de montagnes, elle est à l'origine de leur transformation. Les différentes voies du réseau routier dans les zones de montagne du Dauphiné assurent un trafic régional. Cependant la route permet aussi le plein essor du tourisme au XX° siècle. La route est à l'image des sociétés qui l'utilisent. Ses fonctions évoluent au rythme de l'évolution des sociétés. Les pratiques des usagers de la route changent. Les conditions de circulation en hiver créent la spécificité du réseau routier de montagne. L'hiver et la question du déneigement des routes est au cœur des préoccupations des sociétés de montagne. Par le biais de la question de la viabilité hivernale, il est aussi intéressant d'étudier une évolution des mentalités, de nouveaux usages de la route. / The construction and use of a route depends on many political factors. The road then it is in a state of simple draft is the result of political reflections several scales. Regarding Alpine roads, many issues have to be taken into consideration. If the building is in a national context, the road is also the result of local disputes. It builds territories and new boundaries, new spaces. The road creates inequalities. The road is a symbol of modernity. It is the place where oppose progress and tradition. The alpine roads are the scene of a confrontation between two modes of thought, the engineers, and that of rural societies. If the road allows not always opening up companies mountains, it is the source of their transformation. The different paths of roads in mountain areas Dauphiné provide regional traffic. However, the road also allows booming Tourism in the twentieth century. The road is a reflection of the companies that use it. its functions evolve with the evolution of societies. The practices of road users change. Traffic conditions in winter create the specific road network mountain. Winter and the issue of snow removal is a key concern corporate mountain. Through the issue of winter maintenance, it is also interesting to study a change in attitudes, new uses of the road.

Made available in DSpace on 2014-06-11T19:22:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-08-26Bitstream added on 2014-06-13T18:49:01Z : No. of bitstreams: 1 reis_yc_me_prud.pdf: 4404643 bytes, checksum: d955f1ecd9f11d5c953843527380b5e3 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A presença e utilização de sistemas de navegação em automóveis no mundo, atualmente, é cada vez maior. Esses sistemas são utilizados por pessoas que necessitam de informações navegacionais para alcançarem seus destinos. Entretanto, em muitos casos, são fornecidas apenas a localização do veículo no visor dos sistemas e setas de direção. Diferentes estudos realizados nos EUA, Inglaterra, Japão e Suécia, buscam analisar quais informações os motoristas selecionam do ambiente urbano a partir de sua memória, para assim indicar e conceber sistemas de navegação com informações que auxiliem os motoristas em sua navegação. Esses estudos apontam que o mapa cognitivo dos motoristas é a melhor fonte de informações de guia de rota, pois possui as informações realmente úteis para auxiliar a navegação em automóveis, o que indica ser necessário conhecer as representações internas do ambiente dos motoristas, para assim conceber sistemas que propiciem maior eficiência navegacional. Desse modo, esta dissertação de mestrado objetivou investigar quais aspectos do ambiente os motoristas utilizam durante a navegação. Para tanto, aplico-se o método de esboço cartográfico para seleção de informação de guia de rota em automóvel. No desenvolvimento do método desse estudo participaram 50 (cinquenta) motoristas... / The presence and use of navigation systems in cars in the world is currently increasing. These systems are used by people in need of navigational information to reach their destinations. However, in many cases, are given only the vehicle's location on the systems display and directional arrows. Different studies indicate that the cognitive map of the drivers is the best source of information for route guidance, it has the really useful information to aid navigation in cars, which indicates the need to understand the internal representations of the environment of motorists, so as to conceive systems that provide navigational efficiency. Thus, this dissertation aims to investigate which environmental aspects drivers use when navigate. For that, were applied the method of sketch map for selection of route guidance information in car. In developing the method of this study involved fifty (50) drivers (undergraduate students, postgraduate students and taxi drivers) familiar with ... (Complete abstract click electronic access below)

Submitted by Éver Santoro null (eversantoro@gmail.com) on 2016-07-01T00:26:51Z No. of bitstreams: 1 DISSERTACAO_FINAL_EVER_SANTORO.pdf: 2706152 bytes, checksum: 3bf76419f039aae4fe4e4368c3d7216c (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-07-04T19:07:06Z (GMT) No. of bitstreams: 1 santoro_e_me_bauru.pdf: 2706152 bytes, checksum: 3bf76419f039aae4fe4e4368c3d7216c (MD5) / Made available in DSpace on 2016-07-04T19:07:06Z (GMT). No. of bitstreams: 1 santoro_e_me_bauru.pdf: 2706152 bytes, checksum: 3bf76419f039aae4fe4e4368c3d7216c (MD5) Previous issue date: 2016-06-17 / A cultura da cana-de-açúcar é muito importante para o agronegócio brasileiro, respondendo por 16% da matriz energética do país e sendo uma das fontes de energia mais limpas e renováveis do mundo. A planta é aproveitada na produção de açúcar, etanol, etanol de segunda geração, conhecido como bioetanol, fertilizante e bioeletricidade. Com o aumento constante da produção e a mudança de paradigma da colheita a partir da mecanização, evidencia-se a necessidade de otimização do processo de colheita por tratar-se de uma das principais operações agrícolas, pois, deve atender a demanda de matéria prima na usina com qualidade e a um custo competitivo. Sua representatividade em relação ao custo total da produção da cana-de-açúcar justifica um estudo específico na otimização do processo da colheita mecanizada da cana-de-açúcar. Diante desta necessidade, este trabalho propõe um modelo matemático para otimização da rota na colheita mecanizada da cana-de-açúcar, buscando através da análise do mapa de plantio e considerando as variáveis e restrições existentes no processo, traçar o melhor plano de colheita a ser executado pela colhedora. O modelo proposto é baseado no problema do carteiro rural, que é bastante estudado na literatura. Implementações foram desenvolvidas e testes numéricos foram realizados com dados fornecidos por uma empresa do setor sucroenergético da cidade de Catanduva, São Paulo. Os resultados obtidos foram comparados com as rotas tradicionais de colheita da empresa e confirmaram a eficiência do modelo em fornecer soluções que minimizam o tempo de manobra da colhedora, gerando ganhos econômicos e ambientais. / Sugarcane cultivation is very important in the Brazilian agricultural business, answering for 16% of the country’s energy matrix. It is also one of cleanest and most renewable energy sources in the world. Sugarcane is used in the production of sugar, ethanol, second generation ethanol (known as bioethanol), fertilizer and bioelectricity. With the constant increase in production and the harvesting paradigm shift brought by mechanization, the need to optimize the harvesting process is evidenced by the fact it is one of the most important agricultural operations and it must answer the demand for raw materials at the processing plant with quality and competitive costs. Its representativeness in relation to the total cost of sugarcane production justifies a specific study on the optimization of the process of mechanized sugarcane harvesting. In face of this need, this work proposes a mathematical model to route optimization in mechanized sugarcane harvest, aiming to devise the best harvest plan to be executed by the harvester based on the plantation map and considering variables and restrictions present in the process. The proposed model is based on the rural postman problem, which is broadly studied in the literature. Implementations were developed and numerical tests were carried out with data given by a company of the sugar-energy sector in the city of Catanduva, São Paulo. The results obtained were compared with the company’s traditional harvesting routes and confirmed the efficiency of the proposed model in providing solutions that minimize maneuvering time with the harvester and, therefore, generate economic and environmental gains.

The design of new facilities - buildings, shopping centers, public transport stations, airports, or intersections of urban roads - should consider delays resulting from intense pedestrians’ flows in order to make its' operation more efficient. The general objective of this doctoral thesis is to propose a simulation model to represent pedestrians’ behavior in urban environments. Simulation models should allow planning these environments in order to provide greater levels of comfort and safety for the pedestrian. Agent-based abstraction has been widely used for pedestrian modeling, mainly due to its capacity to represent complex entities. Agent-based models represent agents’ decision-making ability based on their profile and perception over the environment. One of the most important pedestrians’ activities is the route choice. This document describes the development of a route choice model based on friction forces. The route cost calculation considers a balance between distance and the impedance generated by other pedestrians. Simulations runs shown that pedestrians choosing longer routes can have similar or better travel times. The ability of choosing not only the shorter route brings more realistic behaviors for the pedestrians’ representation, especially with small differences in route lengths and higher congestion. On the proposed model agents were modeled with partial knowledge of the network conditions. The knowledge was limited considering the pedestrian estimated field of view. In the real world it is not possible to know the network state before turning the corner. The model was validated and calibrated with real data. Calibrating a pedestrian route choice model is a complex task mainly for two reasons: (i) Many factors interfere on pedestrians’ route choice; (ii) data collection is difficult. To overcome these difficulties real pedestrians were studied in a controlled environment. An experiment was set up inside the university campus. After the calibration process the model was able to simulate a real scenario. Proposed model was applied to simulate a shopping mall environment. Simulate the pedestrians shopping behavior is particularly complex once route choice in shopping malls may be defined by a number of causal factors. Shoppers may follow a pre-defined schedule; they may be influenced by other people walking, or may want to get a glimpse of a familiar shopping. Analysis from simulations indicates that the agents’ behavior provides a promising approach for real case applications.

Esta dissertação busca identificar aspectos carentes de melhorias na modelagem de pedestres. A modelagem do comportamento de pedestres se inicia pelo entendimento de seu processo decisório, entendendo como ele se desloca, realiza escolha de rotas, interage com outros pedestres, veículos, obstáculos, etc. Os modelos de simulação de pedestres estão hoje aptos a representar de forma bastante realista o deslocamento dos mesmos, entretanto, a simulação conjunta com veículos apresenta ainda alguns aspectos fracos devido as grandes diferenças de abordagem na modelagem dos dois modos. A representação da travessia de pedestres nos modelos de simulação tradicionais apresenta limitações que podem impactar nos resultados gerados pelos simuladores. Este trabalho enumera diversos comportamentos de pedestres decorrentes da interação com veículos, no momento da travessia, que geralmente não estão presentes nos simuladores. Uma vez identificados estes comportamentos, uma pesquisa foi realizada com usuários do sistema viário, com idades entre 22 e 60 anos, para avaliar o quanto estes comportamentos são frequentes e importantes na estimativa de tempos de viagem dos pedestres. O comportamento indicado pelos entrevistados como mais impactante nos tempos de viagem foi o de “busca por brecha em caminhada”, onde o pedestre percorre trechos na lateral da via, enquanto observa possíveis brechas na corrente de tráfego para realizar sua travessia. O referido comportamento foi então modelado e agregado a um modelo de simulação de pedestres. Os resultados mostraram que a inclusão do novo comportamento provoca redução significativa dos tempos médios de viagem dos pedestres e que a simulação pode ser mais condizente com o comportamento real de pedestres em diversos ambientes urbanos. Para representar o comportamento de um pedestre em um ambiente urbano, é preciso também estudar como ele escolhe suas rotas. No processo de escolha de rotas, o pedestre é influenciado por diversos fatores, como hábitos pessoais, o número de cruzamentos, níveis de poluição e de ruído, segurança, abrigo de condições climáticas ruins, e estimulação do ambiente. Para representar o comportamento de escolha de rota dos pedestres, foi desenvolvido um modelo que considera a interação entre pedestres como uma impedância alterando a rota do pedestre. O estudo foi inspirado por equações de forças de atrito, considerando que pedestres tendem a evitar passar próximo de outros pedestres com elevada velocidade relativa. Para escolher uma rota o pedestre realiza uma ponderação entre a impedância e a distância a ser percorrida. O modelo foi capaz de reproduzir comportamentos emergentes da interação entre os agentes, permitindo concluir que as equações de forças de atrito adotadas nesta modelagem podem ser uma abordagem válida na representação da escolha de rotas de pedestres, podendo também ser uma forma indireta de avaliação de atrasos. / This dissertation aims to identify aspects in need of improvement in modeling pedestrians. The modeling of pedestrian behavior begins by understanding their decision making process, understanding how people move, make route choice, interact with other pedestrians, vehicles, obstacles, etc. Simulation models of pedestrians are able to represent the way they move quite realistically, however, the combined simulation of pedestrians and vehicles still presenting some poor aspects due to the wide differences in the modeling approach of the two modes. The pedestrian road crossing representation in the traditional simulation models has limitations that may impact on the results generated by the simulators. This dissertation lists several behaviors arising from the interaction of pedestrians with vehicles at road crossing situations, which are generally not present in the simulators. Having identified these behaviors, a survey was conducted with pedestrians, aged between 22 and 60 years old, to evaluate how these behaviors are frequent and important to estimate travel times. The behavior indicated by the interviewees as more impactful in the travel times was the “search for a gap while walking”, describing the pedestrian that walks laterally to the road, in the sidewalk, at the same time that is trying to cross the road, looking for gaps in the traffic stream. Such behavior was modeled and then aggregated at a simulation model of pedestrians. Results showed that the inclusion of the new behavior causes significant reduction in average travel time for pedestrians and that the simulation can be more consistent with the actual behavior of pedestrians in different urban environments. To represent a pedestrian behavior in an urban environment, it is also necessary to study how he chooses their route. At the route choice process, the pedestrian is influenced by several factors, such as personal habits, the number of road crossings, levels of pollution and noise, safety, shelter from bad weather, and other stimulation of the environment. In order to represent the pedestrians route choice behavior was devised a model that considers the interaction between pedestrians as an impedance to alter pedestrians route. The study is inspired by friction forces equations, considering that pedestrians avoid passing near other pedestrians with high relative velocity. To choose a route a pedestrian consider a balance between the impedance and the path length. The model is able to reproduces emergent behavior between agents, allowing the assumption that friction equations adopted in this modeling may provide a suitable approach to route choice behavior and can also be used as an indirect measure of pedestrians delay.

O estímulo aos modos ativos de viagem através de modificações na forma urbana - infraestrutura, edificações e atividades - é objeto do planejamento das cidades contemporâneas desde que os problemas do transporte motorizado se revelaram críticos e contrários à ideia de sustentabilidade urbana. Congestionamentos, poluição, custos monetários e sociais elevados estão associados ao modelo de urbanização e mobilidade da maioria das cidades, especialmente nos países em desenvolvimento, onde a explosão da frota motorizada é concomitante à aceleração dos processos de urbanização e espalhamento urbano. Mais recentemente, a revelação de relações de causalidade entre o excesso de utilização dos veículos particulares e problemas de saúde crônica das populações urbanas levou a um crescimento das pesquisas e iniciativas de estímulo às caminhadas como modo de transporte. Também o interesse pela qualidade da experiência da vida na cidade veio somar-se a este corpo de conhecimento, trazendo as ideias de vitalidade urbana e urbanidade para junto dos estudos de caminhabilidade. O interesse extrapolou a análise de demanda agregada que visa o incremento do modo a pé e passou a dar atenção aos caminhos pelos quais as pessoas se movimentam, conectando origens e destinos nos interior das cidades. Este trabalho procura avançar neste aspecto ao propor um método de avaliação dos atributos da forma urbana baseado no monitoramento de caminhantes com dispositivos de posicionamento global (GPS) e modelos de escolha discreta. Um estudo na cidade de Porto Alegre acompanhou indivíduos durante os anos de 2011 a 2014 e, através da representação de diversos atributos urbanos em ambiente SIG, associou as trajetórias realizadas com as características da forma da cidade, concluindo que elas influenciam a utilidade percebida das alternativas de caminho e, portanto, atuam sobre o processo decisório dos pedestres. Para além da simples distância ou declividade, outras características como o tamanho dos trechos, a hierarquia das vias, a presença de prédios marcantes e espaços abertos e a densidade de edificações ao longo dos eixos revelaram-se influentes neste processo. Poucas intersecções e cruzamentos, predomínio de vias amigáveis ao pedestre e edificações arranjadas de forma menos densa são alguns dos atributos que apresentaram maior relevância para a decisão de “por onde ir” no âmbito deste estudo. A amostra relativamente pequena e a concentração das viagens no entorno do Parque Farroupilha e do campus da UFRGS não permitem generalizar os resultados. Porém, o estudo pode ser considerado válido enquanto exploração, pois constrói uma metodologia que pode ser ampliada e aplicada em outros contextos. Além disso, os resultados revelam particularidades da realidade local que parecem indicar a existência de diferenças comportamentais significativas em relação às cidades do primeiro mundo, tornando-o promissor como instrumento de suporte a políticas e projetos de mobilidade urbana sustentável no Brasil. / Since motorized transport problems have proved to be critical and contrary to the concept of urban sustainability, the idea of increasing the active travel modes through changes in urban form is a key subject of today´s mobility agenda. Traffic congestion, air pollution and severe monetary and social costs are associated with the current patterns of urbanization and mobility, especially in developing countries, where an explosive motorized fleet growth occurs simultaneously to an acceleration of urbanization and sprawl processes. Most recently evidences of a causal relationship between massive use of private vehicles and chronic health disorders have led to an increase in research about walking as an effective and clean mode of transportation. Also, the interest about the quality of life experience in the city came to add up to this body of knowledge, bringing in ideas of livability to walkability studies. Beyond the aggregate demand studies that aim to increase the walking mode share, there is now a growing interest on more localized aspects of the walking phenomenon - the routes - trying to understand the ways in which people travel on foot when connecting origins and destinations. This work proposes a method based on assessing data from actually taken walking trips using GPS devices and on modeling pedestrian´s choice behavior using discrete choice models. A study in the city of Porto Alegre, south of Brazil, followed 82 individuals for three consecutive days and, through the representation of several layers of urban data in a GIS environment, associated their trajectories with the main urban form attributes to allow the modeling experiment. The results show that the built environment features play an important role as a decision attribute, producing perceived utility/disutility on the decision-makers´ minds. They indicated that, in addition to the basic travel effort attributes such as trip distance or street slope, other factors such as the straightness of the trip, the road hierarchy, the presence of busy intersections, landmark buildings, noticeable public spaces and the density of buildings along the walking stretches indeed influence the route choice. The relatively small sample size and the spatial clustering of trips around the city´s central area doesn´t allow to the generalization of results. However, the study can be taken as a valid exploratory analysis, since it builds up a methodology that can be expanded and applied in other urban contexts. Furthermore, the results reveal some particular local features that indicate the existence of significant behavioral differences from the developed cities where previous similar studies were performed. These qualities make the proposed framework a promising decision support tool for sustainable urban mobility projects in Brazil.