Which of the following is not required to build a corridor?

• A. A Surface
• B. An Alignment
• C. A Profile
• D. A Target

Answer: (A)

In Civil 3D, a corridor is built from three core inputs: the horizontal path along which it runs (the alignment), the vertical control along that path (the profile), and the cross‑section shape that defines how the road or path looks at any point (the assembly). The surface is not required to create the corridor itself. You can design a corridor that uses an alignment, a design profile, and an assembly, and that corridor will generate its own surfaces as you work. A target surface is optional; it’s used when you want the corridor to tie to or grade against an existing surface, but you can omit it and still have a functional corridor based on the alignment, profile, and assembly.