I currently have two 2D curves. One of the curves is on the xy plane (all the z-values of the points = 0). The other curve is on the xz plane (all y-values of the points = 0). Essentially what I have is are curves for the alignment and a profile for a roadway.

Is there a way that I can create a 3D curve from these two curves? I want the 3D curve to follow the xy-path of the alignment curve and the vertical path of the profile curve. 

The obvious solution is to discretize both curves into the same number of points, extract the z-coordinate of each of the points from the profile curve and xy-coordinate of each of the points from the alignment curve, create points from these coordinates, and create a curve/polyline from these points.

Is there any way to maintain the curvature of each of the two lines?

Thank you all in advance.