996 resultados para Two-Lane Trafficways.


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General note: Title and date provided by Bettye Lane.

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General note: Title and date provided by Bettye Lane.

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General note: Title and date provided by Bettye Lane.

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The spacing of adjacent wheel lines of dual-lane loads induces different lateral live load distributions on bridges, which cannot be determined using the current American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) or Load Factor Design (LFD) equations for vehicles with standard axle configurations. Current Iowa law requires dual-lane loads to meet a five-foot requirement, the adequacy of which needs to be verified. To improve the state policy and AASHTO code specifications, it is necessary to understand the actual effects of wheel-line spacing on lateral load distribution. The main objective of this research was to investigate the impact of the wheel-line spacing of dual-lane loads on the lateral load distribution on bridges. To achieve this objective, a numerical evaluation using two-dimensional linear elastic finite element (FE) models was performed. For simulation purposes, 20 prestressed-concrete bridges, 20 steel bridges, and 20 slab bridges were randomly sampled from the Iowa bridge database. Based on the FE results, the load distribution factors (LDFs) of the concrete and steel bridges and the equivalent lengths of the slab bridges were derived. To investigate the variations of LDFs, a total of 22 types of single-axle four-wheel-line dual-lane loads were taken into account with configurations consisting of combinations of various interior and exterior wheel-line spacing. The corresponding moment and shear LDFs and equivalent widths were also derived using the AASHTO equations and the adequacy of the Iowa DOT five-foot requirement was evaluated. Finally, the axle weight limits per lane for different dual-lane load types were further calculated and recommended to complement the current Iowa Department of Transportation (DOT) policy and AASHTO code specifications.

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Persistent daily congestion has been increasing in recent years, particularly along major corridors during selected periods in the mornings and evenings. On certain segments, these roadways are often at or near capacity. However, a conventional Predefined control strategy did not fit the demands that changed over time, making it necessary to implement the various dynamical lane management strategies discussed in this thesis. Those strategies include hard shoulder running, reversible HOV lanes, dynamic tolls and variable speed limit. A mesoscopic agent-based DTA model is used to simulate different strategies and scenarios. From the analyses, all strategies aim to mitigate congestion in terms of the average speed and average density. The largest improvement can be found in hard shoulder running and reversible HOV lanes while the other two provide more stable traffic. In terms of average speed and travel time, hard shoulder running is the most congested strategy for I-270 to help relieve the traffic pressure.

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Introduction: Idiopathic Pulmonary Hemosiderosis (IPH) is a rare cause of alveolar hemorrhage, which is seen primarily in childhood. Celiac disease is defined as a chronic, immune-mediated enteropathy of the small intestine, caused by exposure to dietary gluten in genetically pre-disposed individuals. Association of IPH and celiac disease is known as Lane Hamilton syndrome. There are limited number of case reports of this syndrome in literature. Case Presentation: Although there were no growth and developmental delay and gastrointestinal symptoms like chronic diarrhea, chronic constipation, vomiting, abdominal bloating and pain in the two patients with IPH, they were diagnosed with Lane Hamilton Syndrome. After initiation of gluten-free diet, their IPH symptoms disappeared and hemoglobin levels were observed to return to normal. Conclusions: Even if there were no gastrointestinal symptoms in a patient with IPH, celiac disease should be investigated. These patients may benefit from gluten free diet and IPH symptoms may disappear.

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