This category allows you to view and edit the diameter of the largest circle that can be inscribed within the intersection outline. In cases of asymmetric intersection outlines (i.e. where an intermediate turn radius is applied or a circle cannot be fit conveniently within the design), the inscribed circle diameter will be the diameter of the conceptual circle that marks the outside of the circulatory lanes.

Design Guidelines' Inscribed Circle Category Dialog Box

In the dialog box, move the mouse pointer over the controls to view the associated tooltip and then reference the controls described below.

Note: For the purposes of describing the software, it is assumed that Right-Hand Traffic is selected under Traffic Direction in Design Guidelines' General Category. If Left-Hand Traffic is selected, the descriptions with references to a right/left turn path should be interpreted in the opposite direction.

Inscribed Circle Diameter

Specify the inscribed circle diameter.

Truck Apron Width (French and German Regional Design Methods)

Overrun Area Width (British Regional Design Method)

Specify the width of the truck apron / overrun area.

Circulatory Roadway Width (French and German Regional Design Methods)

Circulatory Carriageway Width (British Regional Design Method)

Specify the width of the circulatory roadway / circulatory carriageway.

Legend

For a description of the elements drawn in the roundabout in this category, see Roundabout Illustration Legend.