I have always been frustrated with the way that Civil 3D preforms an Elevation Surface Analysis. This is a great tool, however, the process of running the analysis has always seemed cumbersome to me. There has never been a way to set an interval for the elevation bands or a starting elevation for the bands. The only option was to set a number of ranges and then manually edit the ranges that Civil 3D automatically created for you. This was a tedious and frustrating process.
The good news is that Civil 3D 2012 has fixed this. You now have the option to Create ranges by Range Interval. You can also set the Base elevation to control the starting point for the elevation banding.
In the example above the elevation range is set to 5’ and the base elevation is set to 420. When the analysis was run Civil 3D determined the number of ranges that needed to be created based on the geometry of the Surface with an analysis of 5’ elevation bands starting at elevation 420 and going to the highest point on the surface. Much easier than before and a nice improvement in 2012.