Civil3D DWG to OpenRoads DGN - Best Conversion Method?

You aren't the first person to ask this. While this thread may not answer all your questions, it may give you some information: https://communities.bentley.com/products/road___site_design/f/geopak-inroads-mx-openroads-forum/210211/tips-tricks-for-exporting-civil-3d-corridor-with-super-elevation-and-recreating-in-ord

And are you talking about translating dumb CAD graphics, or are you talking about attempting to retain design intent? I don't believe the latter is possible because of the differences in the way either program defines that data. Others here probably know more than I, but I don't think there is a simple one-to-one way to translate design data.

Thank you for responding, Mary. 

I've read a couple of posts (the most recent was a few years old I believe), in reference to this question and it seems like most people think the best way to convert from dwg to dgn, is to open dwg in ORD and then export/save to dgn. I'm trying to see if there have been any updates that folks have encountered that change this method.

I know that I wont be able to convert the surface.  I am primarily interested in conversion the stupid CAD linework and things, then bring in the xml later on, to create my terrain model, etc.  I noticed things like vegetation graphics/symbols are not converting over.

While I'm not going to speak as an expert, there are a few things that I have noticed over time.

MicroStation/ORD does a much better job converting DWGs (forward and back) than AutoCAD/Civil 3D. AutoCAD support of DGN format is nominal at best, while Microstation has been actively developing the translation algorithms since the '90s.

That said, some elements don't translate across well, if at all - civil design data fits that description. Many times, survey symbols in Civil 3D are Civil Points, with design intelligence behind them. I've seen those not show up correctly in plain AutoCAD as well. I get the best results for drawings with Items like that by first using Civil 3D to export the design features to dumb graphics using the "Export to Civil3D Drawing" option in the C3D menu. This strips out the design data, leaving only the graphics, whic then translate to MicroStation in much better shape.

Another thing to be aware of - I have seen some issues with DGNs and DWGs taken back and forth where they lose their Geographjic Coordinate System. I suspect that AutoCAD writes that into the file differently. The easiest way I've found around it is to set my translation DGN file to the same GCS as my AutoCAD drawing.

Thank you!  I try to export to Civil3D drawing but C3D is telling me to close MicroStation, even though I do not have a session open.  Ooof, I think this is going to be an ongoing issue... 

Good point with the GCS - ive ran into that problem as well.  Additionally, ive been having the USSF and International FT issue going from C3D to ORD.   Apparently, ORD pulls the unit of measure of a dwg drawing from its drawing units in Insertion scale units, under drawing utilities, units.  So that was throwing me off for a bit - glad I caught that and now request the AEC have that changed when they submit files.  I cant wait until we get rid of USSF.  

The way I do it, I will open Civil3D and "Export Civil3D drawing" to create a "plain" DWG drawing. I close Civil3D and open MicroStation. Then I can open/save as/import the DWG with the MicroStation tools. It's a round-about process, but it gives me the best results.

Thank you for the tip on the Insertion Scale units. I know I had been playing with a few settings to figure that out but I never wrote down what I did when...

I wish I could do that method you describe, but I keep getting "an existing MS session has been detected.  Please close the MS session and try again".  I have no MS or anything else open.  Tried rebooting and still getting error.  Others I work with are getting the same error.

I sent my dwg to Bentley, to see if they can somehow export/save it with the vegetation and trees.  I have most things converted now, except those.

I wish I could do that method you describe, but I keep getting "an existing MS session has been detected.  Please close the MS session and try again".  I have no MS or anything else open.  Tried rebooting and still getting error.  Others I work with are getting the same error.

I sent my dwg to Bentley, to see if they can somehow export/save it with the vegetation and trees.  I have most things converted now, except those.