Have jagged contours on your surface? Here are a couple options to smooth them out. Find out which works best for you.
Smooth Surface versus Smooth Contours in Civil 3D
Using Graphics Smoothing - MATLAB & Simulink Example - MathWorks
Creating a Tin Surface from Polylines - Autodesk Community - Civil 3D
Smooth Surfaces from Scattered Data: ILNumerics SmoothSurface
Survey Civil 3D Plus
TBC5.2 - DXF gets bloated when surface contours are included
matlab - Methods for smoothing contour lines - Stack Overflow
Civil3D, Civil 3D Plus
Settings Civil 3D Plus
Surface, Civil 3D Plus
Survey Civil 3D Plus
Contour Smoothing vs. Surface Smoothing
Contour Smoothing vs. Surface Smoothing
Grid Spline Smooth