Alignments do not have elevations assigned to them directly, but obtain elevations from a profile model. As with lot lines, alignments interact with feature lines in the same site. The most common problem is the result of creating a split point where a feature line crosses an alignment, because both objects acquire the same elevation at that point. Split points are explained more fully in the next section, Point Types and Elevation Control.
It is recommended that when you create alignments, do not assign them to a site until the design period is complete. This prevents interaction between alignments, feature lines, and parcels. In Autodesk Civil 3D, the default alignment creation options provide this behavior.