In order to define a roundabout you will first need to identify the alignments of the arms (the incoming roads). If they don’t already exist, draw accurate centerlines of each arm extending to at least to the point where the new roundabout will join any existing road (the blend point).
- Click the New Roundabout button
on the Junctions toolbar or select New Roundabout from the Junctions drop down menu. If you don’t have a default standard set, the Junction Standard Explorer is displayed. - Click on the + to expand the tree view and display the required standard file and group. When you find the required standard, highlight it and click Proceed.
- Depending upon the way your copy of Junctions is configured, the Scale Settings dialog may display at this point. If so, check that you are using the correct scale and units and that the driving convention is correct and then click OK. The Junction Properties dialog is displayed.
- If you wish, at this point, you can enter a Name for the roundabout as well as Notes and/or a Description. You can do this later if you prefer.
- You can also choose a Draw Style from the drop down list. This controls how the roundabout displays.
- You may select an Existing Surface and a Final Surface on which you may project the roundabout.
- Click OK to proceed. A default roundabout is displayed at the cursor.
- Move the roundabout to the required location and left click to confirm. You may use snap modes to get a precise location.
- The roundabout will be drawn in its final location and you will now be prompted to select the first of the arms. Select the arm roughly where you expect it to blend with any existing road. The New Arm dialog is displayed.
- Enter a Name, Description and/or Notes if you wish and click OK. The arm displays with the blend point at the point you picked. However, the arm cannot be drawn if you pick too close to the roundabout so in this situation the arm will be extended by a suitable amount. You may subsequently move the blend point closer to the roundabout once you have finished placing the roundabout. Tip: If you are running in Civil 3D, we strongly recommend that you name the roundabout now so that the alignments are automatically created with the correct names. Autodesk Vehicle Tracking does not rename alignments if you change the roundabout name after creation.
- Repeat this process picking each arm and right click to terminate the New Roundabout command.