Autodesk CIVIL3D - CIVILDESIGNCOMP 2007 SLM CD Tutorials Manual page 529

For more information, see the AutoCAD Civil 3D Help topic Editing Offset
Alignments and Widenings.
Modify offset alignment parameters
1 Open Intersection-Edit-Horizontal.dwg, which is located in the
drawings folder (page 819).
This drawing contains an intersection of a primary road (Road A) and a
secondary road (Road B).
The offset alignments for Road A extend along the full length of the
centerline alignment.
The offset alignment for Road B does not extend beyond the
intersection extents.
The curb returns have widening regions on all four corners of Road
A.
2 Click the intersection marker.
The Intersection tab is displayed on the ribbon. The Modify panel has
tools that you can use to modify the parameters of the horizontal and
vertical geometry of the intersection.
Exercise 1: Editing the Horizontal Geometry of an Intersection | 517
tutorial