In the Canadian arctic, winter roads are engineered across the frozen land, rivers, and lakes. The strength and longevity of these roads depends on particular weather conditions. / Our research focuses on the winter road between Tulita and Norman Wells, Northwest Territories, open since 1982. The opening dates for the winter road are statistically analyzed. Five extreme early-opening years and five extreme late-opening years are determined and subsequently compared to both surface weather observations and large-scale synoptic structures prior to the opening dates for these years. Results show extreme late years are strong El Nino seasons, and extreme early years are colder and have more precipitation during November, than the 1971--2000 climatology. / The analysis of meteorological conditions near Norman Wells, associated with the extreme opening dates for this winter road, provides planners with more precise information germane to this road construction.

xvi, 150 p. : ill. (some col.), maps (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / Floodplain roads and railroads are common features in river landscapes, but their distribution and impacts have not been explicitly studied. This dissertation discusses the impacts of floodplain roads and railroads on channel and floodplain processes in river landscapes at the continental, regional, and local scales. At the continental scale, I documented the spatial patterns of roads and railroads in the floodplains of the continental United States and the regional variability of their potential impacts. Based on these results, I developed a conceptual model based on topography and the interaction of transportation and stream networks that suggests that the area of lateral disconnection caused by transportation infrastructure should be most extensive in mid-sized alluvial valleys in relatively rugged settings, such as those located in the western United States. I used pre-existing digital geologic, hydrologic, and transportation data with Geographic Information Systems software to map floodplain areas and lateral disconnection along the floodplains of two river systems in Washington State. I developed methods to quickly and inexpensively delineate potential or historic floodplain surfaces, to analyze lateral floodplain disconnection caused by different types of structure, and to rank floodplain reaches in terms of salmon habitat potential. Although all floodplains exhibited disconnection, the floodplain maps and habitat rankings helped identify opportunities for habitat preservation and restoration. At the local scale, I mapped and measured the impacts of lateral disconnection, showing that channel and riparian habitat was degraded in locations with floodplain transportation infrastructure confining the channel compared with similar nearby sites lacking such confinement. Railroad grades and road beds function as confining structures in the riparian zone, disrupting flood pulses and the exchange of water, sediment, and biota between channels and their floodplains and within the floodplain. Over longer time periods, these structures can also impede the natural meandering and migration of channels across their floodplains, disrupting the erosional and depositional processes that drive the high habitat and biological diversity characteristic of floodplains. My results show that human-caused disconnections need to be further incorporated into river science and management. This dissertation includes previously published and unpublished co-authored material. / Committee in charge: W. Andrew Marcus, Chairperson, Geography; Daniel Gavin, Member, Geography; Patricia McDowell, Member, Geography; Joshua Roering, Outside Member, Geological Sciences

O presente trabalho apresenta uma comparação entre resultados da análise estrutural da superestrutura de um viaduto em seção celular obtidos do estudo por métodos teóricos e pelo método dos elementos finitos com uso de software adequado, visando a validação dos métodos empregados para obras em seção celular, observando os critérios de tempo, custo e resultados satisfatórios. Foram analisados os coeficientes de distribuição transversal dos esforços na superestrutura de um viaduto quando da ampliação da obra com uso de seção caixão de dimensões diferentes da original e sem haver simetria, visto a ampliação apenas para um lado da obra. Tal determinação apresenta grande importância, visto que o conhecimento das distribuições transversais entre as longarinas que compõem a obra permite a elaboração de projetos de alargamento de pontes mais precisos, buscando a melhor aproximação entre os modelos numéricos e o comportamento real da estrutura. Os resultados obtidos mostraram que os modelos tridimensionais são aqueles que mais se aproximam da condição real da estrutura, porém com alto nível de complexidade para desenvolvimento e uma demanda de tempo elevada. Os modelos de grelha e o modelo baseado na teoria de Fauchart apresentaram resultados divergentes dos modelos tridimensionais, se mostrando conservadores e com respostas imprecisas, não sendo indicados para análise de estruturas em seção caixão. Já o Método de Mason apresentou bons resultados, com valores próximos aos modelos tridimensionais, porém com um prazo mais reduzido de desenvolvimento e obtenção de resultados, caracterizando um método eficiente para estudos de ampliações de obras de arte com seção caixão, quando da análise dos critérios de custo, tempo e resultados. / The present work shows a comparison between results of the structural analysis of a cellular box cross section viaduct superstructure, the results are obtained with analytic simplified methods and with the finite element method using a suitable software, aiming the validation of the methods used for constructions in cellular box cross section, observing the criteria of time, cost and satisfactory results. The stress transversal distribution coefficients for the superstructure of a box cross section viaduct were analyzed for the expansion of the construction with the use of box cross section with different dimensions from the original one and with no symmetry, regarding the expansion only for one side of the construction. Such determination presents a huge importance, once the knowledge of the transversal distributions among the stringer beams that comprise the construction allows the elaboration of more accurate bridge widening designs, searching for the best approximation between the numerical models and the real behavior of the structure. The results showed that the three-dimensional models are those that are closer to the real condition of the structure, but with high level of complexity for development and a high demand of time. The grid model and the model based on the Fauchart’s theory show different results of the three-dimensional models, proving to be conservative and with inaccurate answers, not being indicated for the analysis of box cross section structures. On the other hand, the Mason’s Method showed good results, with values close to the ones of the three-dimensional models, however with a shorter time of development and delivery of results, featuring an efficient method for box cross section artworks widening studies, when analyzing the criteria of cost, time and results.

O presente trabalho apresenta uma comparação entre resultados da análise estrutural da superestrutura de um viaduto em seção celular obtidos do estudo por métodos teóricos e pelo método dos elementos finitos com uso de software adequado, visando a validação dos métodos empregados para obras em seção celular, observando os critérios de tempo, custo e resultados satisfatórios. Foram analisados os coeficientes de distribuição transversal dos esforços na superestrutura de um viaduto quando da ampliação da obra com uso de seção caixão de dimensões diferentes da original e sem haver simetria, visto a ampliação apenas para um lado da obra. Tal determinação apresenta grande importância, visto que o conhecimento das distribuições transversais entre as longarinas que compõem a obra permite a elaboração de projetos de alargamento de pontes mais precisos, buscando a melhor aproximação entre os modelos numéricos e o comportamento real da estrutura. Os resultados obtidos mostraram que os modelos tridimensionais são aqueles que mais se aproximam da condição real da estrutura, porém com alto nível de complexidade para desenvolvimento e uma demanda de tempo elevada. Os modelos de grelha e o modelo baseado na teoria de Fauchart apresentaram resultados divergentes dos modelos tridimensionais, se mostrando conservadores e com respostas imprecisas, não sendo indicados para análise de estruturas em seção caixão. Já o Método de Mason apresentou bons resultados, com valores próximos aos modelos tridimensionais, porém com um prazo mais reduzido de desenvolvimento e obtenção de resultados, caracterizando um método eficiente para estudos de ampliações de obras de arte com seção caixão, quando da análise dos critérios de custo, tempo e resultados. / The present work shows a comparison between results of the structural analysis of a cellular box cross section viaduct superstructure, the results are obtained with analytic simplified methods and with the finite element method using a suitable software, aiming the validation of the methods used for constructions in cellular box cross section, observing the criteria of time, cost and satisfactory results. The stress transversal distribution coefficients for the superstructure of a box cross section viaduct were analyzed for the expansion of the construction with the use of box cross section with different dimensions from the original one and with no symmetry, regarding the expansion only for one side of the construction. Such determination presents a huge importance, once the knowledge of the transversal distributions among the stringer beams that comprise the construction allows the elaboration of more accurate bridge widening designs, searching for the best approximation between the numerical models and the real behavior of the structure. The results showed that the three-dimensional models are those that are closer to the real condition of the structure, but with high level of complexity for development and a high demand of time. The grid model and the model based on the Fauchart’s theory show different results of the three-dimensional models, proving to be conservative and with inaccurate answers, not being indicated for the analysis of box cross section structures. On the other hand, the Mason’s Method showed good results, with values close to the ones of the three-dimensional models, however with a shorter time of development and delivery of results, featuring an efficient method for box cross section artworks widening studies, when analyzing the criteria of cost, time and results.

No description available.

Thesis: M.S., Massachusetts Institute of Technology, Department of Civil Engineering, 1981 / Bibliography: leaves 174-179. / by Wee Beng Aw. / M.S. / M.S. Massachusetts Institute of Technology, Department of Civil Engineering

Though the trucks consist of only 3% of the total registered vehicles in the United States, truck accidents have been a major concern due to the property damage and loss of lives involved. Growth trends show that the truck travel will reach 1 trillion vehicle miles by the end of the year 2000. This increase in truck travel poses a major threat to the safety of both passenger cars and trucks. To improve the safety of the trucks as well as the passenger cars, understanding of the factors affecting the truck safety is essential. Models developed in the past were mostly regression models which tried to relate the truck accidents to the geometry of the highways. But most of these models did not consider all the factors affecting the safety of the trucks. Simulation models were developed in the past to study the dynamic vehicle response to different highway geometry especially, on exit ramps where most of the rollover accidents occur every year. But not enough research was done in the past on the weather and surface conditions affecting the truck safety. The objective of this study is to develop a graphics-based computer simulation model to test the trucks for different geometric features, surface conditions, and truck characteristics on exit ramps and to gain a better understanding of the factors affecting the safety of the trucks. A high-level simulation language SIMSCRIPTII.5 was used in the study to develop a simulation model. To make the model is to understand, graphical windows and animation were included in the model. Three exit ramps were tested in this model. Two of these ramps are existing ramps in southwestern Virginia and they had rollover accidents reported on them in the past. The parameters and other surface and geometric conditions can be changed at any time during the simulation. The model indicated that deceleration lengths provided may not be sufficient for heavy trucks traveling at higher speeds to reduce their speeds to the safe speed limits on the ramps. The posted speed limits may not be suitable for heavy trucks especially when the surface is not dry. The model also indicated that the tractor-semitrailers are more exposed to rollovers than any other type of trucks. / Master of Science

Highway Capacity Manual (HCM) 2010 methodology for freeway operations contain procedures for calculating traffic performance measures both for undersaturated and oversaturated flow conditions. However, one of the limitations regarding oversaturated freeway weaving segments is that the HCM procedures have not been extensively calibrated based on field observations on U.S. freeways. This study validates the HCM2010 methodology for oversaturated freeway weaving segment by comparing space mean speed and density obtained from HCM procedure to those generated by a microsimulation model. A VISSIM model is extensively calibrated and validated based on NGSIM field data for the US 101 Highway. Abundance of the NGSIM data is utilized to calibrate and validate the VISSIM model. Results show that HCM methodology has significant limitations and while in some cases it can reproduce density correctly, the study finds that speeds estimated by the HCM methodology significantly differ from those observed in the field. / by Dusan Jolovic. / Thesis (M.S.C.S.)--Florida Atlantic University, 2012. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2012. Mode of access: World Wide Web.

Over the past decade, road construction has come to represent Chinese engagement with Ethiopia. This study considers the lives of Chinese workers at the lower end of one such project in Tigray, northern Ethiopia. By examining the ways in which Chinese road workers tried to make sense of daily life on the construction site, I reveal the inherent contradictions of a state rhetoric that promoted 'win-win cooperation' ('huying huli hezuo') and 'friendly collaboration' ('youhao hezuo') between China and Africa, and demonstrate the local manifestations of the much-debated 'China Model'. Initial expectations coloured by state narratives, as well as the migrants' own experiences with domestic development, stood in sharp contrast to realities on the ground. Convinced of the goodwill nature of their activities, Chinese workers were puzzled by and resentful of the apparent ingratitude of local Ethiopians, their lack of cooperation, and, worse, repeated attempts to sabotage the construction work. Chinese workers' struggles with development in Africa, I argue, should be understood in relation to their background as upwardly mobile rural migrants at the bottom of the corporate hierarchy, successors of engineers dispatched under Mao Zedong who had enjoyed a respectable reputation at home - a reputation current workers felt they were about to lose - and as citizens aware of their country's status in the world as superior to Africa and inferior to the West. The workers sought to live up to Chinese ideals of development by demonstrating and promoting the virtues of self-development, simultaneous development, and entrepreneurialism. Ethiopians, however, did not concede to these ideas, and their lack of cooperation stirred resentment and expressions of self-pity on the part of the Chinese, who blamed the Ethiopian labourers, their suzhi (human quality), and wenhua (culture) for the limited success of the projects. What Chinese workers failed to realise was that the attitude of Ethiopians was in fact a response to asymmetrical and contested power relations that did not allow for win-win cooperation and friendly collaboration.