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Citation |
Waissi GR, Cleveland DE. Transp. Res. Rec. 1987; 1122: 96-107. |
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Copyright |
(Copyright © 1987, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing) |
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DOI |
unavailable |
PMID |
unavailable |
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Abstract |
Recent AASHTO design policy developments and research have increased needed stopping sight distance lengths on horizontal curves. The mathematical methodology recommended by AASHTO for calculating needed sight clearances across the inside of horizontal curves exists only for the case where the curve is longer than the needed sight distance. There is no explicit exact solution available for the case where the sight distance is longer than the curve, a situation expected to happen more frequently as sight distance needs are increased. This research provides exact solutioons for the case where the sight distance is greater than the curve length for a moving observer. It relates the available sight distance; horizontal curve geometric elements; and location of observer, road object, and clearances to an obstacle to vision located inside the driving path of the observer. The lesser clearances required for these cases are often as much as 50 percent smaller than those obtained using the longer curve case. User-friendly design procedures and aids using these results have been developed and are presented in the paper. They are easily programmable, and can, hence, serve as a part in a decision support system. The methodology should be valuable in evaluation of safety and operation of critical highway locations. Language: en |
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Keywords |
HIGHWAY ENGINEERING; HIGHWAY SYSTEMS - Accident Prevention; TRANSPORTATION - Legislation |