The objective of this project was to develop a model that describes design speed profiles of vehicles traversing horizontal curves on approaches to stop-controlled intersections on two-lane two-way rural highways. Onc...
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The objective of this project was to develop a model that describes design speed profiles of vehicles traversing horizontal curves on approaches to stop-controlled intersections on two-lane two-way rural highways. Once speed prediction models were determined, a procedure for the design of horizontal curves that would accommodate vehicles transitioning from high speeds to a stop was developed. Speed profiles were developed with the use of data from 15 study sites in Nebraska. The multiplicative model was used to provide prediction equations for speed profiles. Separate profiles were created for passenger cars and heavy vehicles because speeds were significantly different. The heavy vehicle data were separated further for alignments with and without horizontal curvature. It was concluded that posted speed, median type, presence of rumble bars, roadway surface condition, and degree of rutting did not significantly affect the vehicle speed profiles at these sites at a 95% confidence level. During the comparison of speeds, it was found that the intercepts of the regression lines for approaches with and without horizontal curves were significantly different in the case of heavy vehicles. The speed of heavy vehicles on tangent approaches was generally about 8 mph higher than on sites that exhibited horizontal curvature. The rate of deceleration remained almost the same on all approaches to intersections, except near the stop. For passenger cars, there was no statistically significant difference between curved and tangent alignments. A guidebook for the geometric design of intersection realignment Methods A through D, referred to in the 2004 Green Book, is also included in the project's report.
In the past two decades, micromechanical modeling has been recognized as one of the best approach in studying asphalt mixture. The micromechanical models have tremendous potential benefits in the field of asphalt tec...
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In the past two decades, micromechanical modeling has been recognized as one of the best approach in studying asphalt mixture. The micromechanical models have tremendous potential benefits in the field of asphalt technology, for reducing or eliminating costly tests to characterize asphalt-aggregate mixtures for the design and control of these materials. In this paper, a comprehensive review of the work done by a number of researchers is summarized, which includes some of earliest models such as the non-interacting particles (geometry not specified and geometry specified models), and the models with particle interaction, as well as the newly development models in recent years. This paper also describes the most recently de veloped Finite Element Network Model (FENM) and a clustered Discrete Element Model (DEM) used in micromechanical modeling of asphalt mixture. Demonstration of these models are provided, where virtual laboratory simulation and laboratory tests were employed. Other ad vances including the nanotechnology application in asphalt mixture is also briefly discussed.
The objective of this project was to develop a model that describes design speed profiles of vehicles traversing horizontal curves on approaches to stop-controlled intersections on two-lane two-way rural highways. Onc...
The objective of this project was to develop a model that describes design speed profiles of vehicles traversing horizontal curves on approaches to stop-controlled intersections on two-lane two-way rural highways. Once speed prediction models were determined, a procedure for the design of horizontal curves that would accommodate vehicles transitioning from high speeds to a stop was developed. Speed profiles were developed with the use of data from 15 study sites in Nebraska. The multiplicative model was used to provide prediction equations for speed profiles. Separate profiles were created for passenger cars and heavy vehicles because speeds were significantly different. The heavy vehicle data were separated further for alignments with and without horizontal curvature. It was concluded that posted speed, median type, presence of rumble bars, roadway surface condition, and degree of rutting did not significantly affect the vehicle speed profiles at these sites at a 95% confidence level. During the comparison of speeds, it was found that the intercepts of the regression lines for approaches with and without horizontal curves were significantly different in the case of heavy vehicles. The speed of heavy vehicles on tangent approaches was generally about 8 mph higher than on sites that exhibited horizontal curvature. The rate of deceleration remained almost the same on all approaches to intersections, except near the stop. For passenger cars, there was no statistically significant difference between curved and tangent alignments. A guidebook for the geometric design of intersection realignment Methods A through D, referred to in the 2004 Green Book, is also included in the project's report.
The Chiang Kai-Shek (CKS) International Airport serves as one of the busiest airports in the region. Currently, CKS International Airport development program is underway and it includes construction of a new passenger...
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ISBN:
(纸本)0784405824
The Chiang Kai-Shek (CKS) International Airport serves as one of the busiest airports in the region. Currently, CKS International Airport development program is underway and it includes construction of a new passenger terminal to accommodate the increasing passenger demand. An Automated People Mover (APM) system connecting this new passenger terminal and the existing terminal is one of the major projects in the overall airport development program. The APM system is located in both of restricted and non-restricted areas and transports passengers travelling between terminals with shuttle operation. In the future, the APM is planned to loop type route alignment and transport passengers travelling among three terminals. Niigata was selected as the supplier of the APM system with its NTS system technology. This paper provides an introduction to the APM system and its unique design features. Copyright ASCE 2004.
Emerging concerns about emissions and increasing energy costs have led to interest in developing and applying electronic devices for energy storage (popularly known as flywheel batteries or simply flywheels) in transp...
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Emerging concerns about emissions and increasing energy costs have led to interest in developing and applying electronic devices for energy storage (popularly known as flywheel batteries or simply flywheels) in transportation applications to recover the energy used in braking rather than dissipating it as heat. Each time a vehicle stops, its kinetic energy is dissipated as heat. Fuel is then used to accelerate the vehicle again. A flywheel energy storage device that stores the braking energy and then reuses it for acceleration has the potential to improve fuel economy and reduce pollution. It is important to evaluate the application of this technology in transit buses to assess better any need for increased development. A three-step computer simulation is used to evaluate the reduced emissions of carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxides (NOx) in a flywheel-equipped bus. First, drive cycles over which buses operate are specified. Second, because flywheel energy storage reduces the effects of acceleration and deceleration to the engine, the emissions models (which are sensitive to acceleration and deceleration modes) are identified and selected. Finally, emissions are computed and compared with emissions for a bus without a flywheel. Results indicate conceptually that the flywheel application reduces acceleration effects, which in turn significantly reduce emissions. It is therefore strongly recommended that the flywheel energy storage device be further researched for transportation applications.
A battery-free identification transponder is presented. It incorporates a dual-beam angle-diversity leaky-mode antenna array, connected to two power divider/combiner networks. The integrated antenna shows 20.4 dBi dir...
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