How to convert a Civil 3D file with contours to a compatible Carlson file

1. Open the file in Civil 3D. Click the “C” in the top-left corner, select “Export”, and then “Export Civil 3D Drawing – Export Autodesk Civil 3D drawings to either AutoCAD DWG or Microstation DGN format.”
   
2. In the “Export Autodesk Civil 3D Drawing” dialog box, select “AutoCAD DWG” in the “Export to file type” drop down menu and choose an option for how to handle XREFs in the “External DWG References” drop down menu. You can also select the export file location and/or a prefix or suffix.
   
3. Click the “Export Setting” button.
   
4. In the “Export Settings” dialog box, make sure “AutoCAD DWG” is selected as the “Export file type” and choose a “DWG file version” from the drop down menu. Make sure it is equal to or older to the OEM Autocad engine being used by Carlson to open the file.  Then click the “OK” button.
   
5. Click the “Export” button.