Introducing a New Curve with Symmetrical Parabolic Curvature for Horizontal Alignment

Abstract

Simple circular curves have been proposed by the road specifications to be implemented in horizontal alignment. In these curves, the centrifugal force is applied suddenly to the vehicles at the beginning of the curve and remains constant at its maximum value until the end of the curve. The current research intends to introduce a new curve for horizontal alignment. This curve is a simplified form of the general transition curve and since it has a Symmetrical Parabolic Curvature, it is called the SPC curve. This curve applies the centrifugal force to the vehicles in a gradual manner. By using the SPC curve, the edge profile matches the curvature and the superelevation would be applied more efficiently to the roadway. Compared to the simple circular curve, the SPC curve has a lower horizontal side offset and applies a smoother vertical tire force to the outer edge of the pavement. The shorter total length of the alignment comprising the SPC curve leads to decreased road construction and maintenance costs. Also, the mechanical simulation shows that vehicles negotiating the SPC curve seem to be less prone to rollover.