Maybe you already use the Subassembly Composer (SAC -was released earlier this summer) to build parametric everythings with Civil 3D corridors. Even if you don't, you may need More from your corridor models. I know I do. They want a pretty picture of that model. They want it NOW.
A Preview of Better Corridor Visualization
Autodesk Labs has released the Corridor Solids Technology Preview for AutoCAD Civil 3D 2012. The software provides functionality to create AutoCAD solids from AutoCAD Civil 3D Subassembly shapes that are contained in an AutoCAD Civil 3D Corridor Model.
Visualize your Civil 3D corridor models in More detail in 2012 releases of Navisworks, 3DS Max, and the new Infrastructure Modeler 2012.
You can create AutoCAD solids in the current drawing or a new drawing by quickly extracting solids from the following objects:
■All regions and baselines in a corridor
■Sub-regions within a corridor (e.g., construction phases)
■Specific subassembly shapes (e.g., retaining wall, tunnel, barrier)
The Corridor Solids Preview does even more so follow the link.