Expand Arm Geometry and click on the Approach tab.
The Design Speed is the design speed of the section of road leading up to the roundabout.
The Central Gap Width is the distance between the offside definition lines of the approaching lanes and the departing lanes.
The Approaching Lanes is the number of lanes of traffic approaching the roundabout and would normally be less than or equal to the number of circulatory lanes.
The Approaching Lane Width is measured between definition lines. On a road with no center gap the offside definition line is the centerline.
The Approaching Crown Line Start Offset is the distance back from the ICD at which the crown line starts to deviate from the approaching lanes offside definition line.
The Approaching Crown Line Offset at Entry defines the position of the crown line at entry to the roundabout. It is measured as a percentage of the entry width from the offside definition line so 0% would be on the offside definition line and 100% would be on the nearside definition line.
The Departing Lanes is the number of lanes leaving the roundabout onto this road.
The Departing Lane Width is measured between definition lines. On a road with no center gap the offside definition line is the centerline.
The Departing Crown Line Start Offset is the distance back from the ICD at which the crown line starts to deviate from the departing lanes offside definition line.
The Departing Crown Line Offset at Exit defines the position of the crown line at exit from the roundabout. It is measured as a percentage of the exit width from the offside definition line so 0% would be on the offside definition line and 100% would be on the nearside definition line.
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.