Roundabout Properties: Roundel: Crown Lines

Expand Roundel and click Crown Lines in the left hand pane.

Crown Lines properties

Select Crown Lines to calculate crown lines. Note that the approach crown lines are not calculated unless this is selected

Select the required crown line type.

Island to Island Crown Lines are straight crown lines from each entry splitter line / ICD intersect point with the next exit splitter line / ICD intersect point.

Circulatory Crown Lines are circular crown lines concentric with the ICD. In some cases, there may be two circulatory crown lines.

The Primary Crown Line Offset is measured from the apron and is expressed as a percentage of the circulatory width. Thus 0% would place a crown line on the apron and 100% would place it at the outside edge of travel way.

Note: The primary crown line must be outside the secondary crown line. If not, the values are swapped. This happens even if the secondary crown line is disabled.

If you require a second circulatory crown line, select Add Secondary Crown Line and enter the Secondary Crown Line Offset which is measured exactly as the first.

Currently there is only one method available to draw the approach crown lines and blend them to the circulatory crown lines, the Stockdale Method. Select Draw Leg Crown Lines to use this option. If you clear Draw Leg Crown Lines then only the crown lines in the circulatory area will be drawn because we have no way to calculate the interface of the approach lines and the circulatory lines.

In all cases the Max and Min values represent the limiting values from the adopted design standard.