After reviewing the files used in Rons design above.... I had previously replied to the follow up post by Ron "BasicT"
Ron
It appears what is hapening is the base geometry file being used has a resolution set to metric values while the file you are placing the cell in uses Feet to define the resolution.
when the cell places the Hz position is worked out but the cell does not construct at the correct elevation. I suspect this is a resut of mis matched units.. Because this does not place correctly terrain is not copying to the placed cell.
The civil cell clips the components but the middle portion does not clip .. this is because the terrain is required for this clip...
As a general practice ALL civil user should be sure there DGN file (Advanced) units coincide. working with mismatched units can at times cause undesirable results. in the instances of feet and survey feet the issue can easily go unnoticed at times, however in the case of meters to feet the issues are magnified.
Additionally working in a 3D file can add complexity (this can be managed but the user needs to be aware of the cooresponding 2D 3D entities that will reside in this one file) this can be avoided by working from a 2D seed and letting the open Roads Technology manage the 3D model (this would then be the equal to the components being displayed in 3D in pre SS3 versions)
One last comment - when referencing Terrain DGNs and Geometry DGNs live nesteing (IMHO) should NEVER be used. The use of live nesting with the new technology introduces complexity that most users will want to avoid. There does NOT appear to be any benifit from using live nesting with Terrain, geometry, and corridors. In some cases circular references can end up causing problems.
HTH