
You can edit 3d polyline vertex elevations two different ways You can use the properties window to edit each vertex and change the Z value or you can use the edit elevations from the modify tab of the ribbon then under feature lines, it is one of the smaller buttons Converting 3D polylines to a surface : AutoCAD. You can use this to do the job just as well, but without the bells and whistles. By using Map 3D, engineers can work with GIS data in a familiar environment.

AutoCAD Civil 3D Tip: Converting Civil 3D Parcels to GIS. Including ArcGIS Pro and ArcGIS Enterprise. How to convert civil 3D to GIS shapefile in AutoCAD? AutoCAD Civil 3D Tip: Converting Civil 3D Parcels to GIS Shapefiles. All the segments of 3D polylines should be necessarily in the same plane. While still in command type 'PO ("Point Object" transparent command) in command-line.

Converting polyline arc to AcDbArc and vice-versa.
