Which object is used to establish an edge within a surface by constraining TIN generation along it?

• A. Breakline
• B. Boundary
• C. Feature Line
• D. Contour

Answer: (A)

Breaklines create defined edges inside a Civil 3D surface. When you add a breakline, the TIN triangulation is instructed to follow that line and not interpolate across it, which enforces a sharp edge along features like roads, banks, or ridgelines. A boundary simply sets the outer extent of the surface and doesn’t impose internal edges. A feature line can carry geometry and can be used as a breakline, but the element that directly constrains TIN generation along a line is the breakline. Contours are elevation lines for display and analysis and don’t constrain the interior triangulation.