With the rise of Lidar and drone surveying, Civil 3D 2015 improved its point cloud engine. Users could attach large point cloud datasets (like .RCS or .RCP files) and:

If you are actively using "autocad civil 3d 2015 15", you are likely maintaining a legacy DOT (Department of Transportation) project. Adhere to these rules.

The 2015 version introduced significant improvements to corridor modeling, which is the core of the software's road design capabilities.