The Basics of a Three-Dimensional Geometric Design Methodology

The three-dimensional axis consists of a sequence of three-dimensional elements (fixed elements, dialogue elements and coupling elements). Fixed elements should always be selected if it is unnecessary to introduce any variation to the course of the axis based on the design conditions. However, if the idea is to adjust the design of the road to match existing geometrical constraints to an even better degree at individual points, dialogue elements must be used. In contrast to the fixed elements, a dialogue element allows the course of the axis to be varied at individual points by altering the parameters without introducing any change to the constellation of fixed points. Coupling elements serve to link fixed and dialogue elements. Calculating the axis using three-dimensional geometrical design elements opens up new opportunities for further developing a design methodology for roads.