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Copyright
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(Copyright © 1985, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing) |
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Abstract
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Travel on rural roadways is noticeably different from travel on urban streets. On the former, vehicular speeds are generally higher, the road surface usually is narrower and not as well marked, and the severity of accidents is greater than for urban highways.
Several studies have pointed out that a high proportion of the accidents that occur on rural curves happen at night and usually involve a single vehicle that runs off the road. For a majority of the rural roadways, those with average daily traffic (ADT) of less than 2,100 vehicles, single-vehicle run-off-the-road (ROTR) accidents have been reported to account for more than 40 percent of all accidents, with nearly one-half at these involving a personal injury or fatality.
Post-mounted delineators (PMDs) of various shapes, colors, and types have been used throughout the United States in an attempt to reduce the number of ROTR accidents. These markers have proved to be effective, especially at night or during adverse weather conditions when roadway maridngs may be covered.
The PMD has been demonstrated to be capable of influencing a driver's judgment of the sharpness of a road curve. This influence can be used to modify the pattern a driver follows through a curve, and thus to promote safety on rural highways.
The three post-mounted delineator systems currently used in Virginia were tested at five sites for their effectiveness in controlling run-off-the-road accidents. The changes in speed and lateral placement noted with the systems in place were taken as driver responses to the systems. The study indicated that drivers react most favorably to chevron signs on sharp curves greater than or equal to 7 degrees and to standard delineators on curves less than 7 degrees. It is suggested that statewide use of delineators based on these findings will improve the safety and uniformity in delineation on the rural highway system.
Language: en |