Development of transitioned vertical curve II Sight distance |
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Affiliation: | 1. Department of Civil Engineering, Lakehead University, 955 Oliver Road, Thunder Bay, Ont., Canada P7B 5E1;2. Department of Civil and Environmental Engineering, Carleton University, Ottawa, Ont., Canada P7B 5E1;1. Department of Architecture and Civil Engineering, Chalmers University of Technology, 412 96, Gothenburg, Sweden;2. IVL Swedish Environmental Research Institute, 100 31, Stockholm, Sweden;1. Department of Civil Engineering, Ryerson University, Toronto, Ontario, Canada;2. Tulloch Engineering, Huntsville, Ontario, Canada |
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Abstract: | The mathematical properties of a new vertical curve that consists of a transition curve (cubic polynomial), a parabolic curve, and another transition curve have been presented in a companion paper. The present paper addresses the sight distance characteristics of this new curve, called transitioned vertical curve. The minimum sight distance and the required curve length are analytically derived for both crest and sag curves, considering various cases related to the minimum sight distance and the lengths of transition and parabolic curves. Using the developed analytical models, example design graphs are established for the length requirements of the transitioned vertical curve based on the upper range of stopping sight distance presented by the American Association of State Highway and Transportation Officials. The transitioned vertical curve, which resembles the spiraled horizontal curve commonly used in practice, represents an alternative to the simple vertical curve especially for sharp vertical alignments. |
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