Abstract: Embodiments of the invention provide a method for creating a complete 3D model of complex infrastructure configurations, such as divided highways, roadway intersections, etc. Current CAD applications have been limited to creating 3D models based on the geometry of a single alignment. In one embodiment, each baseline for a 3D model using four data inputs: a topographical terrain model, an alignment specifying the longitudinal 2D geometry for the structure being modeled, a profile specifying the elevations of the baseline along the horizontal alignment, and the geometry for cross-sectional assemblies along the horizontal and vertical alignments.