Citation

Stewart D, Chudworth CJ. Traffic Eng. Control 1990; 31(2): 88-89.

Affiliation

Aberdeen University.

Copyright

(Copyright © 1990, Hemming Group)

DOI

unavailable

PMID

unavailable

Abstract

About 30 per cent of all accidents on rural roads occur at bends. This may not appear surprising, because of the influence of centrifugal force and restricted visibility, but more subtle factors can determine their safety. Investigation of 'safe' and 'hazardous' bends had indicated that the main difference between them was not whether their curvature was large or small, but whether it was constant or variable. This led to the hypothesis that drivers have more difficulty in perceiving the curvature of a transitional bend, because it can deceive them into maintaining an excessive speed. Three acute, accident-prone bends were therefore converted from transitional to circular alignment. Comparing equal before-and-after periods, accidents have been reduced significantly, by about 80 per cent, and cost-effectiveness has also been high. These results suggest that widespread prevention of accidents at sub-standard bends would be simple and inexpensive, and that design codes should no longer recommend the use of transition curves.