Civil 3D and Coordinate Datums

The survey databased, is just that, a database. Whatever coordinate system you designate in the survey database is the coordinate system it thinks your data is in. If your Cad coordinate system is different than your survey database it will 'convert' the coordinates to the Drawing coordinate system when the points from the database are imported in the drawing.

We have never found this to be a workflow we use in over 10 years of Civil3d use. We set our coordinate system in TBC and it never changes. We never have to convert from one system to another. If we did, i'd do it within TBC as that is our database.

Hopefully that answers your question.