The simple answer is “use LandXML”.
From my Picks and Clicks: LandXML Data article in Professional Surveyor
What Is LandXML?
LandXML refers to a file format (.xml) containing data that has been generated from a civil engineering or land surveying software program.
If you’re hearing about it for the first time and want to learn more about the uses and acceptance of the LandXML initiative, visit www.landxml.org. According to their page LandXML.org in a Nutshell, “… LandXML.org is committed to providing a non-proprietary data standard (LandXML), driven by an industry consortium of partners.”
Simply put, the easiest way to convert, transfer, and archive data between Civil 3D, Carlson Software, Land Desktop, Eagle Point, TerraModel, and many other programs is to use the Import from LandXML and Export to LandXML functions available in these programs. Additionally, many machine control systems allow you to import LandXML files. I am most familiar with the Carlson and Autodesk families of civil/survey programs, so most examples in this article refer to them.
For a little more current look at where LandXML is today, you don’t want to miss this archived webinar from September 2015: If You’re Not Using LandXML, You Should Be… Yes, All of You!
The very best advice I can give to anyone who has years of archived Land Desktop, Terra Model or Eagle Point data and is still able to get into and run those programs is to start exporting all of it to LandXML files – starting yesterday! Many of these programs will be (or already are) impossible to re-install on new Windows computers so take advantage of it while you can.
Since LandXML is the industry standard, having all that data in the generic XML format virtually guarantees that you will be able to convert and work with it in any new software package you use in the future.
In addition to LandXML, Carlson gives you a bunch of different ways to import, export and convert data to and from other desktop, field and machine control software. For instance, here’s the menu for Import/Export Surface Data that’s in Construction, Civil & Survey:
Civil 3d data is, by far, the most difficult data to share… In some cases it’s literally impossible to save data such as points and surfaces and be able to use it in any previous version of Civil 3d!
However, you can use the EXPORTTOAUTOCAD commands in Civil 3d to basically explode all the custom entities so they can be opened and used in other programs or in earlier versions of Civil 3d. Of course, by exploding everything, you essentially lose any perceived benefit of working on the drawing in Civil 3d.