999 resultados para Railroad tracks


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This case study examines the factors that shaped the identity and landscape of a small island-urban-village between the north and south forks of the Middle River and north of an urban area in Broward County, Florida. The purpose of the study is to understand how Wilton Manors was transformed from a “whites only” enclave to the contemporary upscale, diverse, and third gayest city in the U.S. by positing that a dichotomy for urban places exists between their exchange value as seen by Logan and Molotch and the use value produced through everyday activity according to Lefebvre. Qualitative methods were used to gather evidence for reaching conclusions about the relationship among the worldview of residents, the tension between exchange value and use value in the restructuration of the city, and the transformation of Wilton Manors at the end of the 1990s. Semi-structured, in-depth interviews were conducted with 21 contemporary participants. In addition, thirteen taped CDs of selected members of founding families, previously taped in the 1970s, were analyzed using a grounded theory approach. My findings indicate that Wilton Manors’ residents share a common worldview which incorporates social inclusion as a use value, and individual agency in the community. This shared worldview can be traced to selected city pioneers whose civic mindedness helped shape city identity and laid the foundation for future restructuration. Currently, residents’ quality of life reflected in the city’s use value is more significant than exchange value as a primary force in the decisions that are made about the city’s development. With innovative ideas, buildings emulating the new urban mixed-use design, and a reputation as the third gayest city in the United States, Wilton Manors reflects a worldview where residents protect use value as primary over market value in the decisions they make that shape their city but not without contestation.^

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This paper analyses the static and dynamic behavior of the railroad track model in laboratory. Measurements of stresses and strains on a large-scale railroad track apparatus were studied. The model includes: compacted soil, representing the final layers of platform, ballast layer, and ties (steel, wooden, and pre-stressed concrete). The soil and soil ballast interface were instrumented with pneumatic stress gauge. Settlement measurement device were positioned at the same levels as the load cells. Loads were applied by hydraulic actuators, statically and dynamically. After the prescribed number of load cycles, in pre-determined intervals, stresses and strains were measured. Observations indicate that stress and strain distributions, transmitted by wooden or steel ties, behave similarly. A more favorable behavior was observed with pre-stressed concrete mono block ties. Non-linear response was observed after a threshold numbers of cycles were surpassed, showing that the strain modulus increases with the numbers of cycles. © 2009 IOS Press.

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"April 1991."

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There has been a worldwide trend to increase axle loads and train speeds. This means that railway track degradation will be accelerated, and track maintenance costs will be increased significantly. There is a need to investigate the consequences of increasing traffic load. The aim of the research is to develop a model for the analysis of physical degradation of railway tracks in response to changes in traffic parameters, especially increased axle loads and train speeds. This research has developed an integrated track degradation model (ITDM) by integrating several models into a comprehensive framework. Mechanistic relationships for track degradation hav~ ?een used wherever possible in each of the models contained in ITDM. This overcc:mes the deficiency of the traditional statistical track models which rely heavily on historical degradation data, which is generally not available in many railway systems. In addition statistical models lack the flexibility of incorporating future changes in traffic patterns or maintenance practices. The research starts with reviewing railway track related studies both in Australia and overseas to develop a comprehensive understanding of track performance under various traffic conditions. Existing railway related models are then examined for their suitability for track degradation analysis for Australian situations. The ITDM model is subsequently developed by modifying suitable existing models, and developing new models where necessary. The ITDM model contains four interrelated submodels for rails, sleepers, ballast and subgrade, and track modulus. The rail submodel is for rail wear analysis and is developed from a theoretical concept. The sleeper submodel is for timber sleepers damage prediction. The submodel is developed by modifying and extending an existing model developed elsewhere. The submodel has also incorporated an analysis for the likelihood of concrete sleeper cracking. The ballast and subgrade submodel is evolved from a concept developed in the USA. Substantial modifications and improvements have been made. The track modulus submodel is developed from a conceptual method. Corrections for more global track conditions have been made. The integration of these submodels into one comprehensive package has enabled the interaction between individual track components to be taken into account. This is done by calculating wheel load distribution with time and updating track conditions periodically in the process of track degradation simulation. A Windows-based computer program ~ssociated with ITDM has also been developed. The program enables the user to carry out analysis of degradation of individual track components and to investigate the inter relationships between these track components and their deterioration. The successful implementation of this research has provided essential information for prediction of increased maintenance as a consequence of railway trackdegradation. The model, having been presented at various conferences and seminars, has attracted wide interest. It is anticipated that the model will be put into practical use among Australian railways, enabling track maintenance planning to be optimized and potentially saving Australian railway systems millions of dollars in operating costs.

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Resumen: La ciudad de Rosario es la segunda área metropolitana del país que registra una incidencia relevante de asentamientos y población residente en los mismos. La mayoría de los asentamientos se ubica sobre viejos trazos de vías del ferrocarril, pero también los hay sobre las vías en uso y otros terrenos fiscales y privados. Los mismos ocupan el 2% de la superficie de la ciudad y el 15% de sus habitantes. Este estudio se realiza en el barrio San Francisquito, comprendido entre las calles Francia, Avellaneda, Ocampo y Seguí. El objetivo del mismo, es describir las estrategias metodológicas desarrolladas, durante este primer año, en el marco de la investigación. Los materiales y métodos utilizados están descriptos por etapas, en la primera se determinó la muestra de hogares, en la segunda se explica los ajustes al formulario de la encuesta de condiciones de vida y la tercera etapa desarrolla la estrategia de capacitación para el trabajo de campo. La muestra, distribuida por sector y radio; la adaptación de los formularios y los talleres de capacitación son los resultados alcanzados. Considerándose estratégico el fortalecimiento de las capacidades locales para la sustentabilidad del proyecto.

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The recent advances in urban wireless communications and protocols that spurred the development of city-wide wireless infrastructure motivated this research, since in many cases, construction sites are not conveniently located for wired connectivity. Large scale transportation projects for example, such as new highways, railroad tracks and the networks of utilities (power-lines, phone lines, mobile towers, etc) that usually follow them are constructed in areas where wired infrastructure for data exchange is often expensive and time-consuming to deploy. The communication difficulties that can be encountered in such construction sites can be addressed with a wireless communications link between the construction site and the decision-making office. This paper presents a case study on long-range, wireless communications suitable for data exchange between construction sites and engineering headquarters. The purpose of this study was to define the requirements for a reliable wireless communications model where common types of electronic construction data will be exchanged in a fast and efficient manner, and construction site personnel will be able to interact and share knowledge, information and electronic resources with the office staff.

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This paper proposes a method of improving level of service in congested urban railways by means of a triple-track line operation for a highly dense urban area with special travel demand characteristics. Where the future travel demand forecasts show sluggish growth or no growth at all, there is little to no incentives for heavy railway investments like quadruple-track extension and construction of new railway routes to alleviate current railway congestion problems. In such a situation, triple-track line operation can be the best alternative due to its moderate investment cost and ease in land acquisition for just an additional single track along the existing tracks. Our simulation investigation in one of the congested railway lines in Tokyo showed that triple track line operation increases railway capacity by 26% and shortens travel time by 38% in peak direction during morning peak hours. These results are encouraging and are useful for removing current railways problems in Tokyo and in similar urban situations elsewhere.

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This dissertation investigates how the neighborhood of Cidade Nova, located in the western side of the of Natal, is perceived by its residents in order to understand its socio-environmental image, intending to contribute both to define strategies of urban intervention and environmental education in the area and to consolidate a methodology that addresses this kind of problem. The completion of field research used a multimethod strategy to study the socio-environmental image of urban areas. It consists of: (a) review of local history from literature research, data recorded by the City Hall, news published on the city's newspapers and interviews with former inhabitants, (b) application of questionnaires to inhabitants including emotions, visual perception, memory and local social activities, (c) development of a drawing of the district, (d) conducting focus groups with inhabitants, using as a starting point the results obtained in the previous activities. In steps "b" and "c" attended 32 neighborhood residents, 16 of them being Community Health Workers and other 16 persons appointed by them. In step "d" 10 individuals took part, divided into two groups. The result of the research showed a picture of residents coincident with the image conveyed by the media in relation to the issues: violence, garbage, public policy/social support and appreciation of the beauties of environmental (dunes and Parque da Cidade park). Although Cidade Nova has been regarded as a dirty, noisy and dangerous place, most of the participants say they enjoy living on the neighborhood. Overall, the results corroborate and gain theoretical explanations, as they are interrelated. The socio-environmental image is expressed for instance in the elements dunes, dump, railroad tracks and Central Avenue that gain symbolic connotation influenced by time and socio-economic context. The insecurity and other negative characteristics assigned by the inhabitants and the media are parallel to the place attachment, since the environmental legibility, the time/familiarity and territoriality offer inhabitants the preference for place of residence, setting up their social identity.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)