AutoCAD Civil 3D includes AutoCAD Map functionality and has historically included a command MAPEXPORT (not available in Civil 3D 2014 ribbon interface) to export to DGN and other formats listed in the picture below.
While this command is still available, Civil 3D now includes a newer command, DGNEXPORT (Application Menu > Export < DGN), to export to DGN. This command has options to specify the seed file and mapping setup such as layer, linetype – see picture below. Read the Help file to learn more about exporting to DGN and its limitations.
Tip: Before exporting Civil 3D objects to DGN, export the Civil features to AutoCAD using the appropriate EXPORTTOAUTOCAD (Application Menu > Export > DWG) command. In the resultant file, if need be, use BURST to reduce any blocks that remain to AutoCAD entities as well. Burst is similar to explode but maintains attributes and block entity layers and is well suited for this purpose.
You can access the same command using the command EXPORT (Application Menu > Export < Other Formats) and pick the appropriate DGN format.
Read further in the Help file about all the commands to import/export DGN files and associated system variables.
If you have to use MAPEXPORT and it does not work, follow the steps per this Autodesk technical solution.
Ideate Infrastructure Solutions Application Specialist
Gaurav is a well rounded Application Engineer and Project Manager for Infrastructure Solutions at Ideate based out of San Francisco. He has over 15 years experience in construction industry and has been helping numerous small, medium and ENR 500 firms maximize their CAD investment for the last ten years. Gaurav is an Autodesk Certified Instructor and Autodesk Civil 3D Implementation Certified Expert. He has taught at several conferences, CAD Camps and Autodesk University. He has taught AutoCAD, Civil 3D, Land Desktop and Map 3D to thousands of students and helps Ideate develop the Infrastructure Services curriculum and courses. With his extensive CAD technology background he helps Bay Area engineering and surveying firms analyze and improve their design and drawing production process thereby improving productivity and the bottom line. Follow Gaurav on Twitter: @BeGeez
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