-LANDXMLEXPORT command
Exports Civil entities to a LandXML file via Command line

Method
Select the entities you want to export.
Opens the Save LandXML file dialog box where you can specify the location and name of the output LandXML file.
Note: Exports BricsCAD Civil entities, such as Civil points, TIN surfaces, Horizontal Alignments, 3D Alignments, and Strings.