Thanks for your answer but i don't know what I have to do, are those commands in civil 3d or in CadTools? because i haven't found them, neither in Civil nor in CadTools. I looked for it in the autodesk manual and i didn't get anything useful.
On the other hand, I don't understand what you mean with "drape". I'm sorry but English is not my mother tongue and when I looked it up in the dictionary, the meaning I get is cover (with a blanket)
Thank you again