A clever colleague of mine came with this solution, when I had a similar question.
In Civil 3D bring up the network edit tools and open the Pipe Network Vista.
In Pipes, turn off all of the columns except the following:
Start Easting Start Northing Start Invert Level End Easting End Northing End Invert Level
You may need to drag easting and northing so they are in the right order.
Select all (Ctrl+A), right click and Copy to Clipboard
Open excel and paste it in.
Delete the header row.
Insert columns before column A and D
Write LINE in cell A1 and copy it down by double clicking the lower right corner of the cell.
File -> Export -> Change file type -> CSV (location not important)
Close Excel.
Rename the csv file to OUTPUT.SCR. Double click to open it in notepad.
CTRL H to do a find and replace for the following:
“LINE,” changes to “ LINE “
“,,” changes to “ “
“m” changes to “”
Now remove the first space at the beginning of the document and save.
Drag the file into a blank autocad file, it will create 3d lines on the current layer.
Press escape to cancel the line command. Save in the project folder.
