Autodesk CIVIL3D - CIVILDESIGNCOMP 2007 SLM CD Tutorials Manual page 521

Specify the intersection location and primary road
1 Open Intersection-Create-3.dwg, which is located in the
folder (page 819).
This drawing contains an intersection of two alignments, Road A and
Road C. Offset alignments exist on either side of Road A, and there is an
existing intersection north of Road C.
2 Click Home tab Create Design panel
Create Intersection.
3 In the drawing, click the intersection point of the Road A and Road C
alignments.
4 Click the Road A alignment to specify it as the primary road.
Exercise 3: Creating an Intersection with Existing Geometry | 509
tutorial drawings
Intersections drop-down