Arranged surface of a road/rail


I would like to create an arranged surface as a mesh by combining the existing terrain and the bottom of the cut volume as shown in the picture.

The volumes come from a linear infrastructure design software as closed polysurfaces.

Are there any GH plug-ins that can help me automate this? or any workflow suggestions might help.

Thank you!

You can find below a download link for the rhino file with the objects shown in the picture.
Rhino File