Here is a 10min video walking you through the creation of a design surface in Civil 3d. The available civil 3d data is an existing ground surface and an alignment. The available cross sections are no more than polylines drawn on a grid. The trick revealed in the video is how to recreate the cross section geometry in its true 3d position within the model.
I recorded a longer version (1hr) at the FLUG Conference on 2011-10-28.
