starting with a data ref surface of existing is a good start.
I would not promote it though, because it's not necessary to do so.
I generally start with a corridor which defines proposed roadways. I build a surface using the corridor tools.
Then I add feature lines as breaklines outside the corridor to the corridor surface.
In some cases I add pond contours as contour objects into said corridor surface.
The surface will project itself between and corridor objects and and additional data like contours or breaklines etc....
as long as all these parts are ment to be connected I keep them in the corridor surface. If there is a separate bearm all by itself I might start a new surface and paste the corridor surface into it. Then make a new surface for the berm and paste it into the composite surface.
Site grading is one of the really fun aspects of C3D.
Dan
Dan
Civil 3D 2013
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