Before you save the preset, make note of the roundabout drawing standards .xml file that is currently selected for the roundabout. Any changes or additions you make to presets are saved within that .xml file.
On the roundabout dialog box, click the button in the Predefined Parameters To Import section of the dialog box.
The Preset - Add dialog box is displayed.
In the Preset Name field, type in a unique name to identify this set of presets.
Note: All roundabout presets are stored in the currently selected roundabout drawing standards .xml file, located by default in C:\ProgramData\Autodesk\C3D <version>\enu\Data\Corridor Design Standards\Imperial or Metric. The Preset name identifies a particular set of presets that are defined in that file. This provides a way to quickly create your own custom XML file to define these settings.