Embodiments of the invention provide a method, apparatus and article of manufacture for modeling a variety of three-dimensional (3D) utility networks constructed from individual network part elements. In one embodiment, users may construct a utility network by selecting and assembling a network of inter-connected parts, where each part is selected from a pipe and structure list. Connectivity among parts is established through part placement. Structure and connected pipe properties may be managed as a single property set. As parts are placed in the utility network, auto-sizing logic resizes existing structures to connected pipes. Pipes and structures are represented by part model data that defines a set of common behavior and properties. When a user modifies part model data or property sets or moves inter-connected parts, a logic component resizes and automatically updates any associated two-dimensional and three-dimensional views of the utility network.