Thanks, @KirkWM
I could extract contours before the volume surface.
Also, that method is not the output I’m looking for.
The output I want from the TIN volume surface is the contours at 0 elevation on the volume surface.
（Contour at 0 elevation on volume surface = line of intersection between two surfaces）
I’m aiming to program with Dynamo based on the flow of the post below, but I want to omit 1, 2, and 4.
⇒「Surface Analysis User Defined Contour Data Constructor - ValueError: lineTypeId - #5 by mzjensen
Do you have any suggestions?
By the way, the Civil3D command MINIMUMDISTANCEBETWEENSURFACES cannot be used because it is not implemented in the Civil3D API.