Grading Design of Side Slopes Fitting Roadside Topography

Abstract

Preparing the grading plan of the side slopes on a highway section is an effective way to obtain an overall three-dimensional view of the entire design area, and a design fitting the roadside topography. Flattening the slope on the ends where the cut or fill is light and gradually steepening it toward the controlling maximum is suggested by the American Association of State Highway Transportation Officials (AASHTO) in order to achieve a smooth appearance. In the present technical note a method to obtain this goal is proposed and applied to a highway's cut area. Depending on the slope's height two different slope ratios are used. Cut slopes are rounded using a parabolic curve with a vertical axis centered on the point of intersection of the original ground surface and the backslope. The length of the curve is determined according to the slope height. The method suggested in the present technical note is a simple and effective way to produce a successful sideslope grading design.