SMOOTH ALIGNMENT OF ROADS

This thesis gives a new method for alignment of roads. Its purpose is to give to road designers a simple, efficient and versatile tool for their work. Classical methods for road alignment use almost only three classes of curves: line segments, circle arcs and cornu spirals. (on a cornu spiral, the curvature is a linear function of the arc length.) assume that the superelevation (a measure of the slope to the right or to the left) of a road surface is chosen so that a vehicle, travelling with a preassigned speed, gets a minimized tendency to skid. If classical alignment is used, the mathematical model of the road surface has folds along certain lines. In this text, cornu spirals are replaced by a class of curves, called p-curves, such that folds do not occur. (on a p-curve, the curvature is a polynomial function of the arc length. The degree of a polynomial under consideration is at most five.) this thesis gives a FORTRAN program for determination of road lines and road surfaces. It is carefully explained how to use the program. For those interested, there is a chapter on the background in mathematics and mechanics. Four examples with complete input and output are given. Alphabetical tables for notation (in FORTRAN) and concepts are included. (some of the concepts have been defined just for this method.) an appendix gives charts for measuring the radius of curvature of a curve at points of interest. (Author/TRRL)