946 resultados para Road-rail vehicles Australia
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Transportation Systems Center, Cambridge, Mass.
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Federal Railroad Administration, Office of Research and Development, Washington, D.C.
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Transportation Systems Center, Cambridge, Mass.
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National Highway Traffic Safety Administration, Washington, D.C.
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Transportation Department, Washington, D.C.
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Transportation Department, Washington, D.C.
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Transportation Department, Washington, D.C.
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Transportation Department, Washington, D.C.
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Transportation Systems Center, Cambridge, Mass.
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Mode of access: Internet.
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This paper analyzes the relationship between freight accessibility and logistics employment in the US. It develops an accessibility measure relevant for logistics companies based on a gravity model. This allows for an analysis of the accessibility of US counties focusing on four different modes of transportation: road, rail, air, and maritime. Using a Partial Least Squares model, these four different freight accessibility measures are combined into two constructs, continental and intercontinental freight accessibility, and related to logistics employment. Results show that highly accessible counties attract more logistics employment than other counties. The analyses show that it is very important to control for the effect of the county population on both freight accessibility and logistics employment. While county population explains the most variation in the logistics employment per county, there is a significant relationship between freight accessibility and logistics employment, when controlling for this effect.
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The large scale development of an Intelligent Transportation System is very close. The main component of such a smart environment is the network that provides connectivity for all vehicles. Public safety is the most demanding application because requires a fast, reliable and secure communication. Although IEEE 802.11p is presently the only full wireless standard for vehicular communications, recent advancements in 3GPP LTE provide support to direct communications and the ongoing activities are also addressing the vehicle to vehicle case. This thesis focuses on the resource allocation procedures and performance of LTE-V2V. To this aim, a MATLAB simulator has been implemented and results have been obtained adopting different mobility models for both in-coverage and out-of-coverage scenarios.
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This article provides a new methodology for estimating fuel consumption and emissions by enabling a correct comparison between freight transportation modes. The approach is developed and integrated as a part of an intelligent transportation system dealing with goods movement. A key issue is related to energy consumption ratios and consequent CO2 emissions. Energy consumption ratios are often used based on transport demand. However, including other ratios based on transport supply can be useful. Furthermore, it is important to indicate which factors are associated with variations in energy consumption and emissions; especially of interest are parameters that have a higher incidence and order of magnitude, in order to fairly compare and understand the difference between transport modes and sub-modes. The study finds that the use of an energy consumption equation can improve the quality of the estimates. The study proposes that coefficients that define the energy consumption equation should be tested to determine market niches and sources of improvement in energy consumption according to the category of vehicles, fuel types used, and classes of products transported.