Regional Design Method

Generates and edits roundabout designs by applying design guidelines (see Design Guidelines) to user-drawn reference geometry to determine the locations of the road edges.

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.

• The Generate Roundabout tool requires the presence of user-drawn lines and/or arcs to become reference geometry for the roundabout design. Using the line and/or arc tools in AutoCAD or MicroStation, draw the reference geometry that represents the roundabout’s approach leg centerlines.

  • The reference line defines the separation of the traffic flow directions and normally aligns parallel with the straight section of the median closest to the center of the roundabout.

• It is recommended that you create a new design guideline appropriate for the current design (see Design Guidelines' New Design Guideline).

For an example of how the Generate Roundabout tool works, please play the Generate Roundabout tutorial (for information on how to play a tutorial, see Tutorials -> Play).

Generate Roundabout / Edit Roundabout 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: The options in the dialog box may be different depending on the selected regional design method.

Design Guideline Section

Design Guideline

Select the desired Transoft Vehicle Envelopes design guideline from the list.

View

Click this button to view the selected design guideline.

Note:

• As you select a design guideline, its parameters are automatically applied to the current roundabout. To return to the previous design guideline parameters, select the original guideline in the Design Guideline list.
• After you place the central island and add at least one approach leg, you will be able to select only those design guidelines that use the same design method as the current design guideline.

Central Island Section

Easting and Northing

Specify the location of the central island in the drawing. The Easting value determines the distance eastwards of the roundabout center from the origin. The Northing value determines the distance northwards of the roundabout center from the origin. As you move the pointer in the process of placing the central island, TORUS dynamically updates the values in the Easting and Northing boxes.

Button	Option	Click to...
	Move Central Island	Move the roundabout central island to a new location. After you click the button, click the roundabout, move it to the desired location, and then click to place the roundabout and return to the Generate Roundabout dialog box.

Hint: The optimal location for a roundabout central island is the point through which all reference lines pass. If a reference line cannot be aligned through the center point, you may shift the central island so that the reference line can pass through the central island to the left of the center point.

Note: If the center position of a French Design Method roundabout is adjusted, TORUS will draw the legs along a line from the far end of the original reference lines to the new center of the roundabout.

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.

Button	Option	Click to...
	Configure Circulatory Roadway/Carriageway Width	Override the circulatory roadway/carriageway width specified in the current Design Guidelines' Inscribed Circle Category.

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.

Button	Option	Click to...
	Draw Truck Apron / Overrun Area	Turn the truck apron on/off. By default, this feature is turned on.

Footprint Section

A footprint offset is the distance from the edges which can be used to approximate the additional space for sidewalk, utilities, and rights-of-way when evaluating the space for a roundabout location. To have a footprint offset added to the roundabout, select the Draw with offset check box, and then specify the desired safety buffer width value in the corresponding box. By default, the Draw with offset check box is cleared, and no safety buffer is added.

Toolbox Section

Button	Option	Click to...
	Add Legs	Add one or more approach legs to the roundabout.
	Delete Leg	Delete an approach leg from the roundabout.
	Edit Legs	Edit approach legs' parameters.
	Replace Leg Reference Geometry	Replace the reference element of an approach leg by picking a different reference element in the drawing. Note: An alternative to using this tool is modifying the reference geometry of an approach leg directly in the drawing by using object grips. If you drag a grip of a line, an arc, or a polyline reference element, the roundabout design will update accordingly.
	Rotate Leg	Rotate an approach leg around the center of the central island by moving the mouse pointer around the central island as desired.
	Save Roundabout Template	Save the current roundabout design as a template so that it can be used with the Roundabout Wizard tool. Note: This button is only available when the roundabout has at least three legs.
	Save Design Iteration	Save the current roundabout design as an iteration so it can be recalled later.
	Roundabout Summary Report	Generate a roundabout summary report.