This category allows you to view and edit the splitter island offsets, exit/entry radii, length and corner radii as applicable to regional design method roundabouts.

Design Guidelines' Splitter Island 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.

Circulatory Entry / Exit Offset

Specify the offset values. These are the distances from the edge of the Inscribed Circle Diameter (ICD) to the splitter island on the entry and exit sides of the leg.

Entry / Exit Circulatory Radius

Specify the radius values. These are the splitter island corner radius values on the entry and exit sides of the leg.

Entry / Exit Circulatory Offset

Specify the offset values. These are the distances from the splitter island envelopes to the splitter island on the entry and exit sides of the leg nearest to the inscribed circle diameter.

Entry / Exit Tip Offset

Specify the offset values. These are the distances from the splitter island envelopes to the splitter island on the entry and exit sides of the leg nearest to the tip.

Tip Radius

Specify the radius value. This is the splitter island tip radius.

Regional Design Method

The following values are applicable to regional design method roundabouts.

Splitter Island ICD (Inscribed Circle Diameter) Offset

Specify the splitter island ICD offset value. This is the distance from the edge of the ICD to the splitter island.

Splitter Island Envelope Entry Radius (British Regional Design Method)

Specify the splitter island envelope entry radius value.

Splitter Island Entry Offset

Specify the splitter island entry offset value. This is the distance from the entry width (British: edge created by the entry radius) to the splitter island on the entry side.

Splitter Island Envelope Exit Radius (British Regional Design Method)

Specify the splitter island envelope exit radius value.

Splitter Island Exit Offset

Specify the splitter island exit offset value. This is the distance from the exit width (British: edge created by the exit radius) to the splitter island on the exit side.

Splitter Island Length

Specify the length of the splitter island.

Corner Radius

Specify the corner radius value in the box (French: or click Calculate Corner Radius and then specify a factor to calculate the value or vice versa).

Legend

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