Civil 3D Subassembly Composer: A Quick-Start Guide Subassembly Composer (SAC)
In Civil 3D, a is a drawing object that defines the geometry for corridor sections, such as lanes, curbs, or ditches. While Civil 3D provides a vast library of stock components, unique engineering challenges—like complex grading or specific structural details—often require custom solutions. The Subassembly Composer allows users to build these "smart" objects that react dynamically to targets like surfaces, offsets, and elevations. Key Components of Subassembly Logic civil 3d subassembly composer tutorial pdf