General Knowledge

Civil Roundabouts is a tool for designing plan layouts of circular road junctions.  Roundabouts are constructed using Civil Geometry elements and concepts, therefore you are encouraged to familiarize yourself with Civil Geometry Alignments.

The elements that make up a roundabout are bound together as a roundabout object.  These elements are related by rules and allow edits to ripple through the rest of the roundabout.

Roundabout Libraries

Roundabout libraries act similar to seed files that allows one to place a standard roundabout layout on an alignment configuration.  These libraries adapt automatically regardless if an approach is straight or curved , skewed or not.

Place Roundabout 

Civil Roundabouts require the presence of either Civil Elements or Civil Alignments for placement.  Refer to Civil Geometry Alignments for details.

Click the Open Library Browser tool found in MX v8i on the Roundabout Task menu.  It summons the Roundabout Library Browser shown below:

 

Select a roundabout from the browser, the preview pane will show an image of the selected roundabout.  Click the Place Roundabout button.  First select an approach element/alignment for the first Reference Feature.  Follow the dialog and/or the cursor prompts to guide the roundabout placement.

                                                                      

Continue element/ alignment selections until all the Reference Features have been identified.  Right-click to end the selection of approaches.  Last, set the center point of the traffic circle.

                                                        

The number of approaches will depend on the alignments selected.  If a selected alignment does not intersect the proposed diameter of the circulatory area, an approach will not be created for it.  For example, selecting a single alignment and a center point will place a roundabout with only two approaches, or one approach if the center point is at one end of the alignment.

Modify A Roundabout 

Select the roundabout element to be modified (circle, approach, island, flare, etc.).  Use MicroStation’s Element Information Tool to make changes or click the on-screen Manipulators to edit the value.  Refer to Civil Geometry Alignments for more information about Manipulators.

If any problem is caused when editing the roundabout, the affected elements are re-symbolized into dashed lines that indicate a problem needs attention.  Messages will be displayed on the Civil Message Centre to guide you to a solution.

Add An Approach 

1. From the Roundabout Library Browser select the desired approach.
2. Click the Place Approach button.
3. Select the roundabout to be edited.
4. Select the alignment for the new approach.

Replace An Approach

1. From the Roundabout Library Browser select the desired approach.
2. Click the Replace Approach button.
3. Select the Approach to Replace by picking any feature that forms part of the approach.  The parameters on the library approach are copied to the selected approach.

Delete An Approach

Use the MicroStation Delete Element tool to eliminate an approach.

Related Documentation

Welcome to MX v8i

Civil Geometry Alignments

MX Conversion