Publication Details

Safety effects of geometric improvements on horizontal curves

Type: Paper

Author(s): Zegeer, Charles V.; Stewart, J. Richard; Council, Forrest M.; Reinfurt, Donald W.

Publisher: UNC Highway Safety Research Center

Publication Date: Aug-1991

Number: UNC/HSRC-91/8/3

Address: Chapel Hill, NC

Abstract: Horizontal curves represent a considerable safety problem on rural twolane highways. A 1980 study estimated that there are more than 10 million curves on the two-lane highway system in the U.S.  Accident studies further indicate that curves experience a higher accident rate than do tangents, with rates that range from one and a half to four times higher than similar tangents. While accidents on horizontal curves have been a problem for many years, the issue may perhaps be more important in light of improvements being made related to resurfacing, restoration, and rehabilitation projects, commonly known as the 3R program. These improvements generally consist of selective upgrading of roadways within the available right-of-way usually following the existing alignment. Because the surface of the road must be continually repaved to protect the underlying roadbed structure, the issue of what else should be done at horizontal curves to enhance (or at least hold constant) the level of safety is critical at this time.