ABSTRACT
The growing use of advanced three-dimensional (3D) computer-aided-design (CAD) models to design and construct complex structures is changing the traditional patterns of design collaboration and documentation. This paper discusses the challenges of 3D model-based collaboration in design; it examines the early design process of Professor Pollalis’ team working on the design competition of the Main Street Bridge project in Columbus, Ohio, in spring, 2002. Prof. Pollalis, the designer of the bridge, used a NURBS-based CAD program to augment the form-finding process, and to accurately represent the intended geometrical design of the bridge. This computational approach had a major advantage over the use of two-dimensional (2D) drawings: it clearly defined and represented the geometry of the structure. Because it was also used directly for structural analysis, it reduced data re-entry, and improved the designer’s control during concept development. Eventually, the 3D model was shared so team members could produce the physical model required for the competition and the architectural and construction sequence drawings. It was also immediately available to the engineers of record as the primary design representation of the geometry, in the next phases of design development.
However, we argue that this kind of model-based information exchange requires a redefinition of design roles and procedures which are not reflected in conventional processes, as they are based on 2D documents. Current standard design contracts do not define 3D models as contractual documents and therefore do not properly address problems that project participants may encounter during design development and construction. Such problems include but are not limited to (1) who owns the model; (2) who controls and operates on the geometric model; (3) how design participants access and verify the validity of the 3D geometry. Lack of proper definition of responsibilities and control of the 3D model may result in ineffective control of the geometry; at worst, 3D data may be transferred into 2D drawings that do not adequately represent the design. Then, participants other than the designer may unilaterally institute design changes, often without cause. This paper examines the “inner” design team’s model-based collaboration during the competition, and suggests steps an owner should take to reinstitute smooth collaboration on the 3D model in later stages when that owner assembles the design development and construction teams. For such a collaboration model to succeed, the legal contracts must be modified so the designer is in control of the final product.
