Effective Safety Factors on Horizontal Curves of Two-lane Highways

The aim of this study was to detect and identify factors in vehicle accidents on horizontal curves in rural roads (two-lane highways). Several factors appear to act upon the safety performance of horizontal curves. These factors include traffic volume and mix, geometric features of the curves, cross section, roadside hazards, stopping sight distance, vertical alignment superimposed on horizontal alignment, distance between curves and also between curves and the nearest intersections or bridges, pavement friction and traffic control devices. This study found that the most important independent effective variables in horizontal curves' crashes based analysis was carried out which means significant are: degree horizontal curve (Dc), total length segment of horizontal curve (Let), superelevation horizontal curve (Ec), length spiral curve (Lsp), shoulder width (Sw) and offset variable average daily traffic (ADT). The yielded equal CR.No = (ADT) (365) (L) (10-6) EXP (-10.5606250 + 108732Dc+0.000840Lct+0.096255Ec-0.584166Lsp-0.196970Sw)responses. Honzontalcurveshavehighercrash rates than straight sections of similar length and traffic composition; this difference becomes apparent at radii less than 1000 m. The increase in crash rates becomes particularly significant at radii below 200 m. © 2010 Asian Network for Scientific Information.