Roundabout

Use this function to design/modify roundabouts.

• The function can handle any type of roundabout (skew intersection, intersection on horizontal curves, etc.) and can have any number of legs (approach roads/road arms).

The resulting roundabout will be a 2D drawing. To design a 3D roundabout, follow any of these two methods:

1. Create a new road task and a new line task in Novapoint.

   • The centerline of the roundabout is saved to the Quadri model.

   • The profile of the centerline of the roundabout is designed using the module Alignment Design.

   • The cross-section of the roundabout is designed using the module Road modeler.

2. Integrate the roundabout in the road model.

   • The resulting road model will have two arms and the remaining arms are connected using secondary road models.

• Elevations to the 2D roundabout drawing can be defined using the Elevation Tools.

Run the function from the following locations:

MOUS_ICO Toolbar: Intersection Design: Roundabout

MOUS_ICO Menu: Road > Intersection Design > Roundabout

The dialog Roundabout will pop up.

• The dialog is a floating window, which allows working on other Novapoint/CAD functions without exiting this dialog.

• The left pane of the dialog gives a tree structure view of the legs (after defining the roundabout location and legs).

• All the legs will be listed in the left pane. The parameters of the leg are grouped into four headings. The headings are available when at least one leg is defined.

• The right pane displays the parameters for the active heading.

Procedure

1. Draw the alignments/centerlines of the legs of the roundabout being designed.

2. Define the parameters of the central island, apron/shoulder width, roadway width, bicycle lane width, etc., on the heading Roundabout.

3. Insert the roundabout using the button Insert <.

4. Select a road island type from the pull-down menu and add leg(s) using the button Add Leg(s) <. View the properties of the reference line (line/alignment selected for adding leg) using the heading Reference Line.

5. Define the parameters of Road Marking and Kerbstone for the road island on the heading Island.

6. Define the parameters of Exit Lane and Approach Lane for the leg on the heading Lanes and Footpaths.

7. Define the parameters of Give-way Line on the heading Give-way Line.

8. Repeat steps 5 to 7 for all the legs of the roundabout. Refer to Shortcut Menu below for copy, paste, etc., options.

9. Define the drawing settings using the button Drawing Settings.

10. Mark the checkboxes Deflection Control and Entry Angles to include these details in the drawing.

11. Draw the roundabout using the button OK - Draw.

Roundabout Parameters

Under the heading Roundabout in the left pane, the parameters of the central island are to be defined.

The values of the parameters can be edited from the respective edit fields in the right pane.

• To edit the values, highlight the value and enter the new value.

• The parameters d, D, Bo, Ko, and Bc are interrelated.

Tip: Select the heading Roundabout in the left pane and hit View Parameters to see the graphical representation of the parameters.

Insert <

Defining the center of the roundabout (intersection of the legs).

• Select the central island diameter from the pull-down menu at the upper right corner of the dialog.

• Edit the values if any changes are to be made to the default values.

• Click the button Insert <.

Command prompts for:

Pick roundabout origin:

Pick the point using the snap modes or enter the co-ordinates of the origin of the roundabout.

Add Leg(s) <

Initiating the Road Islands and Legs

Four types of road islands (Parallel Island, Triangle Island, Trumpet Island, and Trumpet Island (aRc-Line-aRc)) can be designed. Select the type of island to be designed for the leg being initiated and use the button Add Leg(s) < to initiate the centerlines of the legs to the function.

Command prompts for:

Pick centerline(s) as arm:

Select all the legs and finish with the right button of the mouse or the key Enter.

• If all the legs should have the same road island type, select the road island from the pull-down menu at the upper right part of the dialog, click the button Add Leg(s) < and select all the legs.

• If two or more types of road islands are being considered, operate the button Add Leg(s) < multiple times by changing the type of road island.

Once a leg is selected, the details of the same will be displayed in the dialog. All the legs will be listed in the left pane in a tree structure. Each leg will have 4 subheadings of all the parameters of the roundabout.

Reference Line

The details of the alignment/line/arc/polyline selected for adding leg will be displayed under this heading. None of these parameters can be edited as the system reads these details from Quadri Model/CAD for the selected object/entity.

Island

The parameters of the Island are listed under this heading.

• All the parameters related to Island can be defined/edited under this heading.

• The right pane of the dialog has the list of the parameters.

• The bottom of the right pane has two tabs Island and Kerbstone.

• The parameters can be edited/defined by highlighting the value in the right pane and entering the new value.

• The entities of the selected head in the left pane will be highlighted in the CAD drawing.

Tip: Select the heading Island in the left pane and click View Parameters to see the graphical representation of the parameters.

Lanes and Footpaths

Exit and Approach Lane Details

Highlight the heading Lanes and Footpaths in the left pane to see the parameters listed in the right pane.

• The bottom part of the list area has two tabs; Incoming and Outgoing.

• The parameters of the incoming lane of the leg are defined with the Incoming tab and the parameters of the outgoing lane of the leg are defined with the Outgoing tab.

• The parameters can be edited/defined by highlighting the value in the right pane and entering the new value.

Tip: Select the heading Lanes and Footpaths in the left pane and click View Parameters to see the graphical representation of the parameters.

Give-way Line

Highlight the heading Give Way Line in the left pane to see the parameters listed in the right pane.

• The triangles drawn at the outgoing lane of the leg are the entities related to the heading Give Way Line.

• The parameters h, a, and b are the lengths of the sides of the triangle.

• L is the width of the outgoing lane at the start of the outgoing lane.

• R is the radius of the curved surface, on which the triangles will be placed.

• V is the angle.

• The parameters can be edited/defined by highlighting the value in the right pane and entering the new value.

Shortcut Menu

There are options to copy the data of the parameters from one leg to the other.

• Highlight the heading in the left pane and activate the shortcut menu.

• Depending on the heading selected, the respective menu will pop up where users can copy the details defined and apply the same to the other leg.

• Highlight the leg, which is complete, activate the shortcut menu, and select Copy All.

• Highlight the leg, to which the copied data is to be applied, activate the shortcut menu, and select Paste.

• The same can be applied individually for Island and Lanes and Footpaths.

• Other available options are Erase and Reset.

• For the heading Give Way Line the shortcut menu has options Hide/Show. The related entities will be displayed accordingly.

Drawing Settings

Use this button to configure the drawing setup of different lines of the roundabout. The dialog Roundabout -Drawing Setup will pop up.

• Desired drawing setup for different lines of the Roundabout can be selected using this dialog.

• The different lines of the Roundabout are grouped in seven different groups.

• The group number assigned for different lines of the Roundabout can be identified from the preview of the dialog.

Configure objects

The line type and color for the first four groups (1 to 4) are customized using the buttons LT and the color field.

• Only the line types available in the current drawing can be selected. To select new line types, exit this dialog, load the line types using CAD function and recall this dialog.

• 1 - Central Island

• 2 - Inscribed Circle

• 3 - Tangent lines for the legs

• 4 - Give-way Lines

Select line setup

The drawing setups for groups 5, 6, and 7 are selected from the drawing setups listed in the respective pull-down menus.

• Select the desired line configuration from the pull-down menu for each group.

• 5 - Road Islands (Kerbstone and Road Marking)

• 6 - Centerlines (legs)

• 7 - Road Edge lines (Road Edges, Shoulder Lines, Cycle Track, Refuge Lines)

Line Setup

Use this button to configure the drawing style. The dialog Alignment Style Editor will pop up, which allows configuring existing styles (predefined and user-defined) and creating new styles.

Deflection Control

Deflection and Entry Angles are the two main ways to check the 2D design of a roundabout. All roundabouts must adhere to the rules of these parameters. Deflection is meant to be as crucial as Entry Angle though it is much easier to fix than Entry Angle.

• Mark the check box to have them drawn.

Calculation of Deflection

• Offset the centerline of the leg, inner curb/shoulder line of a central island, and the road edge line (curb) by 1.0m as shown in the illustration below.

• Draw a circle using the command Tan, Tan, Tan Circle of CAD on these three offset lines.

• The radius of the circle is the Deflection.

• The deflection (radius) should be as per the road standard.

• A = Centerline of the leg

• B = Kerb line

• C = Road edge line (curb)

• D = Offset lines (1.0m)

• E = Circle drawn using Tan, Tan, Tan Circle

Entry Angles

Entry Angles and Deflection are the two main ways to check the 2D design of a roundabout. All roundabouts must adhere to the rules of these parameters.

• Mark the check box to have them drawn.

Calculation of Entry Angle

• Draw 3 perpendicular lines from the deflection island (kerbstone) to the shoulder line as shown in the illustration below.

• Draw an arc through the mid-points of these 3 lines and extend it to meet the inscribed circle (see the illustration).

• Draw a tangent to this arc at the intersection point with the inscribed circle (see the illustration).

• Similarly, obtain the tangent to the exit road.

• The entry angle is given by [90-(θ/2)], where θ is the included angle of the tangents (see the illustration).

• The entry angle should be as per the road standards.

• A = Deflection Island

• B = Kerb line

• C = Perpendicular lines

• D = Arc through the mid-points of the perpendicular lines

• E = Inscribed circle (extend the arc)

• F = Tangent line to the arc

• G = Included angle (θ)

OK - Draw

After defining all the legs and the respective parameters, click OK - Draw. The program draws the 2D drawing of the roundabout.

After drawing the roundabout CAD command prompts for:

Insertion point for the Node:

MOUS_ICO Pick a point and the Node will be inserted which will be helpful for editing the Roundabout at a later stage. The Node contains all the relevant data for the Roundabout.

Edit

Use this button to modify an existing Roundabout.

Command prompts for:

Select Node:

Select the node of the roundabout, which is to be edited.

The selected roundabout will be highlighted (changed to edit mode). Edit the values of the parameters where modifications are required to be done.

Tip: One can also edit roundabout using the function Object menu (NCO) and select the node.

Next topic: T-Intersection