Expand Arm Geometry and click on the Slip Lane tab.
Select whether to add a single or double slip lane in Lanes.
Set the defaults for the Overall Road Width, the Inner Lane Width and, if a double slip lane is selected, the Outer Lane Width.
In all cases the Max and Min values represent the limiting values from the adopted design standard and the Default value will be used when the roundabout is first placed. A default value MUST be provided but Max and Min may be blank if there is no limiting value.