Calculating the area of a 3D Polyline, using RTOPO software

It's about calculate the area of a road.
First, I loaded a XYZ file of points, representing a road.
3D Polyline may contain gaps (also defined by 3D Polyline).
I make a copy of 3D Polylines that define the surface.
Now I define a line that connects the ends of Polylines.
Using the Join command, I generate a single 3D Polyline from the 3 Polylines.
I selected the 3D Polyline and I converted it into a closed 3D Polyline.
Then is made the triangulation of the surface defined by the exterior and interior 3D Polylines.
Finally, we ask the area calculation of the triangulation.