Digital Building Modeling & Facilities Design

Build It First Digitally (ENR, October 10, 2005) describes General Motors Corporation's use of 3-d digital modeling to fundamentally change the design and construction of two manufacturing facilities: the 2.4 million square foot Lansing Delta Township vehicle assembly plant and the 442,000 square foot addition to the Global V6 engine plant in Flint, Michigan.

In the case of the Flint plant, benefits attributed to the new techniques include a 24-week reduction in the typical 85-week construction schedule, completion of construction 5 weeks ahead of schedule, and zero change orders for building component interface conflicts (i.e., conflicts between piping, ductwork, structure, and other such elements). Michael Neville, vice president and project principal at Ghafari Associates, the architectural/engineering technology integrator on the project states, "In 26 years I have never seen a project run with more collaboration and be so simple."

According to ENR, the design process worked as follows: At the end of each week, updated design data was delivered from design subcontractors to the technology integrator. Over the weekend, this data was integrated into the shared building model, and collision detection routines were run to identify physical conflicts between elements. On Mondays, the design team would meet to review and resolve conflicts. (In initial runs, as many as 3000 collisions were detected.) Once design was complete and all conflicts resolved, the building model was "locked" and all parties agreed to construct the building according to the design model.

Other impacts of a building information model-centric design process included:

• Loosening of GM's traditionally rigid design software standards to accomodate the specialized building information modeling tools used on the project
• Elimination of paper progress submissions at 30%, 60%, and 90% design completion
• Use of the building model for the development of $5.5 million in value engineering savings at 90% completion of design
• Gains in construction efficiency with greater reliance on off-site prefabrication of assemblies, reduced construction waste, and reductions in on-site worker forces

Moving forward with future projects, GM predicts savings of 3% to 5% per project through elimination of systems interference alone, not including additional savings due to reduced construction time.

For more on related topics, see other articles in this site's Innovations In Building Design & Delivery category.