Aspects of Highway Superelevation Design

The method of calculating superelevation in highway curves and its effects on vehicle dynamics and safety is of great importance in highway design. United States and German guidelines' relevant methods are presented and compared in this paper. The main differences between these two methods are related to design and operating speed concepts and their use to calculate superelevation for curve radii exceeding the absolute minimum. Some modifications to the current AASHTO superelevation design approaches are proposed, based on the relationship between the degree of curve and actual operating speeds, to harmonize highway superelevation design with drivers' actual speed behavior, which could enhance highway safety.