Citation

Lah FA. J. Transp. Eng. 2005; 131(11): 843-850.

Copyright

(Copyright © 2005, American Society of Civil Engineers)

DOI

unavailable

PMID

unavailable

Abstract

The 2001 AASHTO publication A Policy on Geometric Design of Highways and Streets (Green Book) discusses five different methods for the distribution of side friction and superelevation rates for curves with radii greater than the minimum and recommends one of the methods for rural high-speed roads design, Which is most commonly used in practice. The use of the five methods for distribution of superelevation and side friction, use of various maximum superelevation rates in adjacent jurisdictions, in addition to the use of various side friction factors for various facility types as outlined in the Green Book (rural high-speed roads, low-speed urban streets, and turning roadways) have greatly contributed to varying driving comfort and safety ranges for various highways in the United States. This study provides a theoretical analysis for selection of superelevation rates based on a set value of speed beyond the design speed (or speed limit) at which drivers start feeling lateral acceleration. This study is an attempt to simplify the complexities of this topic and provides a more consistent and clear design method.