In this year's release of Autodesk AutoCAD Civil 3D (2016), a new tool was added to the Belgium, Netherlands and UK country kits that allows to extract geometry from corridor models in a way it can be easily used for AMG.
This tool automates multiple steps that need to be taken when exporting the information manually.
The tool allows selecting multiple feature line codes in one or all corridors in a civil 3D drawing.
The feature lines with the selected codes then can be exported to 3D polylines in the current or a new clean AutoCAD drawing.
In many cases the corridor design contains multiple baselines and regions, resulting in multiple feature lines for e.g. the edge of pavement. When manually exporting these feature lines, the result will be a set of disconnected 3D polylines. This new tool allows joining these polylines during export.
If the styles of the corridor feature lines have been setup in a good way, the exported feature lines will be grouped on different layers.
The video below show how this works: