Move the center(s), specify the shape, and configure other settings of the roundabout's central island.

Configure Central Island Dialog Box

Shape Section

Select the shape of the central island.

Circle

The central island is drawn in the shape of a circle. See Dimensions Section: Circle.

Ellipse

The central island is drawn in the shape of an ellipse with two centers. See Dimensions Section: Ellipse.

Dumbbell

The central island is drawn in the shape of a dumbbell with two centers. See Dimensions Section: Dumbbell.

Configuration Section

Button	Option	Click to...
Circulatory Offsets	Configure Circulatory Offsets	Override the circulatory offsets specified in the current Design Guidelines' Circulatory Offsets Category.

Apron Width / Vehicle Method

Turn automatic determination of the truck apron width on/off. By default, this feature is turned on, and TORUS determines the truck apron width based on the Inscribed Circle Diameter or the Central Island Diameter value and the behavior of the design vehicles assigned in the current Design Guidelines' Vehicles Category. To specify the truck apron width manually, turn this feature off, and then type the desired apron width value in the corresponding box.

Dimensions Section

This section contains settings based on the Shape selected above.

Circle

Inscribed Circle Diameter

Select this option and then specify a value to override the default inscribed circle diameter value from the current Design Guidelines' Inscribed Circle Category.

Note: By default, TORUS uses the Inscribed Circle Diameter value and the corresponding design vehicle behavior to calculate the Central Island Diameter and Truck Apron Width / Overrun Area Width values.

Central Island Diameter

Select this option and then specify the desired value. To apply the new value, press TAB. TORUS will update the Inscribed Circle Diameter value accordingly.

 

Ellipse

Center to Center

Specify the distance between the centers.

Loop 1 Radius (R1) / Loop 2 Radius (R2)

Specify the radius of the outside of the circulatory roadway.

Connect Loops with Tangents

Select this check box to draw tangents between the extents of each loop.

Dumbbell

Center to Center

Specify the distance between the centers.

Loop 1 U-Turn / Loop 2 U-Turn

Select this check box to allow the circulatory roadway to complete a full circle.

Loop 1 Radius (R1) / Loop 2 Radius (R2)

Specify the radius of the outside of the circulatory roadway.

Loop 1 Deflection (D1) / Loop 2 Deflection (D2)

Specify the amount to skew the roundabout by.

Note: This is an offset from the center of one end of the construction line connecting the loop centers.

Reverse Radius (RR1) to Reverse Radius (RR4)

Specify the radii of the arcs connecting the circulatory roadway and straight sections.

Median Width

Set the outside width of the circulatory roadway lanes between the centers.