This paper examines constraint strategies appropriate for modeling three-dimensional geometry in civil engineering design. Offers reviews of research and identifies three basic constraint approaches: (1) the algebraic approach, which represents constraints as equations; (2) the deductive approach, which represents constraints as logical predicates; and (3) the constructive approach, which represents constraints as geometric operations. The two aspects of constraint organization covered include: (1) hierarchical constraints, creating and manipulating constraints in meaningful groups; and (2) assembly constraints, defining constraints on the overall geometry of an assembly.