Exercise 2: Adding an Approach Road to a Roundabout

In this exercise, you create the geometry for another approach road that remains dynamic to both the roundabout and the specified centerline alignment.

Select the approach road

1. Open Roundabout-Approach-Add.dwg, which is located in the tutorials drawings folder.
2. Click Home tab Create Design panel Intersections drop-down Add Approach  Find.
3. Click the Roundabout_ISLAND alignment.
   
4. Click Road D, which is to the north of the roundabout.
   
   When the roundabout was created in Exercise 1: Creating a Roundabout, Road D was selected as an approach road, but only the southern end of it was added to the roundabout. When an alignment passes through a roundabout center point, only the alignment end that you click is added as an approach road. In this exercise, you add the other end to the roundabout.
5. Press Enter.
   The Create Roundabout - Approach Roads dialog box is displayed. You use this dialog box to specify the geometry and alignment properties of the roads that meet at the roundabout.

Specify the approach road parameters

1. In the Create Roundabout - Approach Roads dialog box, under Predefined Parameters To Import, select RG = 20.
   When you change this setting, the Approach Road Parameters section is populated with preset values. You will learn how to modify and save these values for later use in Exercise 4: Setting Up Roundabout Design Standards and Presets.
2. Under Approach Road Parameters, change the Entry Flare Length value to 75.
3. Specify the alignment parameters:
   • Alignment Style: Roundabout - Approach Road
   • Alignment Layer: 0
   • Alignment Name Prefix: Approach_SN
   • Alignment Label Set: Roundabout - Approach Road
4. At the bottom of the dialog box, click Next.

Specify the island parameters

1. For Predefined Parameters To Import, select RG = 20.
2. At the bottom of the dialog box, click Next.

Examine the roundabout components

Note:
On the Markings and Signs page, accept the default values.
1. Click Finish.
   The approach road is displayed in the drawing.
   
2. In Toolspace, on the Prospector tab, expand the Alignments collection.
   The alignments that have a prefix of Approach_SN (1) were automatically created during this exercise.