What is the purpose of associating a surface to a pipe network?

• A. To set the top elevations of structures
• B. To determine pipe diameter
• C. To compute flow rates
• D. To assign materials

Answer: (A)

In Civil 3D, associating a surface to a pipe network makes the ground surface control where the network sits vertically. The surface provides elevations at each structure location, so the top elevations of structures like manholes and other access points are aligned with the terrain. This ensures the network sits with the correct cover and matches the existing ground, and it will update automatically if the surface changes. The association does not determine pipe diameter, compute flow rates, or assign materials, which are determined by design choices and separate analyses or data.