Introduction and Analysis of Parameters of a New Curve for Use in Roadway Geometric Design

Abstract

Abolfazl Taherpour*, Erfan Ghadermazi, Mansoureh Jeihani and Mohammad Amin Nozari

Commonly used curves in roadway design include simple curves, multi-centered compound curves, and clothoid curves. The most critical parameter of any curve is its radius of curvature, which depends on factors such as design speed and parameters like friction and superelevation. This paper introduces a new curve that is similar to a clothoid, where the radius of curvature varies across points on the curve. However, it differs in its mathematical formulation and construction methodology. This curve enables a linear increase or decrease in curvature, making it suitable for ramps and sections where entry and exit speeds differ or where continuous changes in curvature are required. The paper derives the geometric characteristics of this curve and explores its potential applications in roadway design. Parameters such as enclosed area and length of the curve are calculated and compared with conventional compound curves. The findings of this study highlight the advantages of the proposed curve as an alternative to multi-centered compound curves in roadway design. Its performance in linear transition, coupled with its straightforward implementation, makes it a promising candidate for practical applications.

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