Hello there. I have “mission impossible” problem. I have some 3D representation of alignment in Civil3D and I can extract points from that alignment. Is there any solution that can approximate that list of points with a series of arcs? But each point of two adjacent arcs must be the tangency point for both arcs. Main problem is, actually, that I need to represent road tunnel in Revit, and because of that I need continuos curve or at least curve from series of arcs.

I believe there is a node to approximate a nurbs curve by a series of arcs. Try searching for fit or approximate.