Evaluation of horizontal curve radius in overlap with longitudinal slope and vertical curve

ABSTRACT

The equations used to calculate horizontal curve radius are presented in geometric design regulations based on the following assumption: the curve is on the flat ground without overlap with longitudinal slope or any vertical curve. The aim of this study is to evaluate the effect of overlapping longitudinal slope and vertical curves on the horizontal curve radius. For this purpose, three different cases are investigated: horizontal curve in a flat road, horizontal curve in a sloping road, and horizontal curve in the presence of a vertical curve. For the above-mentioned cases, different forces are exerted on the vehicle. The direction of their effect is modeled using the point-mass method, and the equations for determining minimum horizontal curve radius are extracted. The results demonstrate that the equations for the overlap of a horizontal curve with a crest vertical curve indicate a need for increasing the horizontal curve radius in some cases.

KEYWORDS:

• Crest vertical curve
• geometric design
• horizontal curve radius
• longitudinal slope
• road safety
• sag vertical curve

Disclosure statement

No potential conflict of interest was reported by the authors.

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.