Control Single Plane Tangency & Vector Rotation

Hi folks. Having trouble controlling the direction of my lines. The attached is part of a road (bridge deck) creation node and the part I can’t for the life of me figure out is how to make Dynamo draw a line both sides, perpendicular to the NurbsCurve direction, but level in the perpendicular plane so I can add my own road crossfall slope. The crossfall slope (or superelevation) is constant over the path (.035 vert in 1 horiz in this case but should be a variable) sloping towards the center of the curve radius. (The actual road only has one curve in practice- the attached is to illustrate better) Any help would be appreciated very much! :slight_smile: Lines_TangentPerpendicularNurbsCurve.dyn (11.2 KB)