Learn how you can limit the length of labels in Civil 3D so that they fit the area that you have available and the geometry you are labeling with this tutorial.
For the complete tutorial, (and many others) follow this link...
.

Better Elevation Banding In Civil 3D
Purging Styles from Civil 3D Drawings
Labeling Pipe Network Structures from the Top or Bottom in Civil 3D
Tips to Improve Civil 3D Performance
Improve Civil 3D Performance by Optimizing Label Styles