Regional Design Method

Add approach legs to the roundabout, and edit approach legs' parameters.

Note: This tool requires existing CAD geometry in the drawing to act as the leg reference geometry. The geometry may consist of lines, arcs, or polylines/complex chains. Lines and arcs can be combined within the polylines/complex chains.

Add Leg / Edit Leg 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.

Name

Specify a name for the approach leg.

Properties Section

Button	Option	Click to...
	Draw Entry Lanes	Turn the approach leg's entry lane on/off. By default, the approach leg's entry lane is turned on. The entry path radius value is displayed in the box on the right. Specify the number of lanes for the approach leg entry.
	Configure Entry Lane	Override the entry path radius and offsets specified in the current Design Guidelines' Legs Category. Note: This button is only available if an entry lane is turned on.
	Draw Exit Lanes	Turn the approach leg's exit lane on/off. By default, the approach leg's exit lane is turned on. The exit path radius value is displayed in the box on the right. Specify the number of lanes for the approach leg exit.
	Configure Exit Lane	Override the exit path radius and offsets specified in the current Design Guidelines' Legs Category. Note: This button is only available if an exit lane is turned on.
	Preview Entry/Exit Path Radii	Turn the approach leg's entry/exit path radii preview on/off. By default, the approach leg's entry/exit path radii preview is on.

Leg Length

Specify the length of the selected approach leg.

Splitters & Crosswalks Section

Button	Option	Click to...
	Draw Splitter Island Envelope	Turn the splitter island envelope on/off. By default, the splitter island envelope is on.
	Draw Splitter Island	Turn the splitter island on/off. By default the splitter island is on.
	Draw Pedestrian Refuge	Turn the pedestrian refuge on/off. By default, the pedestrian refuge is on. Note: This button is only available if Draw Splitter Island is on.
	Draw Crosswalks	Turn the crosswalks on/off. By default, the crosswalks are on.
	Configure Splitter Island	Override the splitter island offsets specified in the current Design Guidelines' Splitter Island Category.

Crosswalk Offset

Specify the pedestrian refuge/crosswalk offset value. This is the distance that the refuge is located from the inscribed circle diameter.

Maximum Splitter Island Length

Specify the length of the splitter island.

Calculated Output Section

Expand this section to view the widths of the entry, entry and exit lanes, the median, and the refuge as well as the entry angle measured using Method 1 and Method 2 (see Appendix -> Entry Angle Measurement).