Design/Delivery Process Innovation Using BIM

Design/Delivery Process Innovation Using BIM

The award winner in this category was GHAFARI Associates for its work on the Flint Global V6 Engine Plant Expansion for General Motors in Flint, Michigan. GHAFARI is a multi-disciplinary firm providing full-service architecture, design, and engineering services to a global client base that includes the aviation, automotive, corporate, industrial, healthcare, education and government sectors. It is one of the leading firms at the forefront of multi-disciplinary BIM implementation, which was described in detail in the AECbytes Feature article "Multi-Disciplinary BIM at Work at GHAFARI Associates" published last November. Let's take a closer look at its work on the Flint project which won it the BIM Award for "Design/Delivery Process Innovation Using BIM."

The Flint project is a 442,000 sq. ft. addition to a Global V6 engine plant for General Motors. GHAFARI was the A/E of record and the BIM integrator for the design/build team, working in collaboration with the lead contractor, The Ideal Contracting Inc. They were presented with the challenge to design and deliver this manufacturing facility under an extremely fast-tracked schedule of less than 40 weeks, while keeping the costs under control and maintaining the highest standards of quality and safety during construction. A comparable fast track design/bid/build could have required approximately 60 weeks from design to project closeout, while a fast track conventional design/build approach would have required approximately 50 weeks. To meet the schedule and cost requirements, one of the most critical requirements was that of ordering the 4500 tons of steel from the mill in less than 3 weeks from the start of design, as opposed to the normal time frame of 8-14 weeks. If the steel mill order could not be issued within the required 3 weeks, the mill rolling cycle would have been missed and the team would have been forced to order steel from the warehouses, significantly increasing cost.

The owner and the design/build team agreed from the start of the project to use 3D BIM during design and construction, as they knew that it could not be delivered on schedule and within budget if the team was to use conventional delivery systems and methodologies. The design team created 3D BIM models for all disciplines including architectural, structural, HVAC, plumbing, fire protection, and electrical systems using different Bentley BIM solutions (see Figure 3). The entire design was fully coordinated using the 3D models, after which the 2D documentation was extracted from them. Both the fully coordinated 3D models and the associated 2D documents were then released to the sub-contractors, who used the 3D models to produce installation drawings and, in some cases, to also drive their fabrication equipment. Even after the ownership of the models was transitioned to the sub-contractors and detailers, the design team continued to review the install level models with the sub-contractors until all issues were resolved prior to construction. Because of this process and the commitment from the installing contractors to build-to-the-model, there were zero changes due to design conflicts during the construction of the project.

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Figure 3. Multiple vignettes of the use of BIM on the Flint project. (Courtesy: GHAFARI Associates)

Important as 3D BIM was to the success of this project, also critical were factors such as advanced planning, supply chain project management, and team commitment to apply lean principles. GHAFARI created a dedicated advanced technologies group for the project that took the lead in applying lean construction principles and 3D enabled delivery for eliminating wasteful practices especially at handoffs between design, detailing, fabrication, and installation phases. A lean concept called "Kaizen Bursts" was used at various stages of the project to streamline workflow. Kaizen Bursts are short and focused sessions that include value stream mapping, analysis, and workflow re-engineering aimed at eliminating non-value adding activities. Collaboration was also greatly enhanced by key members of the design/build team including the A/E, sub-contractors, and the owner's engineering team co-locating at the offices of the General Contractor for approximately 3 months. At this co-location center, the design/build team worked closely to clarify project objectives, define scope, and fully coordinate the design prior to construction. As design decisions were being made, they were incorporated in the BIM models and reviewed for cost and constructability. Subsequently, all coordination and collaboration activities proceeded with weekly on-board reviews of the 3D model instead of the traditional 30/60/90 paper-based review.

An example of the use of a Kaizen Burst was in meeting the 3-week mill order date by eliminating wasteful activities inherent in 2D paper-based delivery at handoffs between the A/E and the fabricator. The A/E and the fabricator agreed to utilize intelligent 3D model exchange. The A/E's 3D analysis model was transmitted directly to the steel fabricator, who imported it into the detailing software and extracted steel quantities directly from the 3D model (see Figure 4). This allowed the key mill order date of 3 weeks to be met and the fabricator was able to start the detailing process early. The fabricator continued to submit weekly up-to-date steel 3D models to the A/E, which were distributed to the design/build team for coordination.

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Figure 4. Eliminating waste at handoffs and the use of steel interoperability in the Flint project. (Courtesy: GHAFARI Associates)

Not only did the use of 3D BIM allow thousands of interferences to be detected and resolved prior to construction, the final 3D models were fully detailed to the installation level, which allowed the sub-contractors to maximize the benefits of off-site fabrication and pre-assembly. They were able to produce detailed quantity takeoffs and order material exactly as required. By delivering Just In Time (JIT) to the construction site, the time spent at the construction site was significantly reduced. It also allowed components to be installed to very tight tolerances, reducing waste. The construction site was well organized—construction crews rarely overlapped and dumpsters remained empty during construction due to the increased use of offsite fabrication, pre-assembly, and JIT delivery. Structural steel erection was completed 35 days early, with no changes during installation. MEP systems were also installed without any field rework. Installation of piping and HVAC systems was completed during the first few months of construction. The elimination of field changes, as well as reduction in the movement of people and material, improved site safety. The elimination of field changes also improved morale—workers took pride in their work by knowing they were installing it right the first time. The project was finally delivered to General Motors almost 5 weeks ahead of schedule (15% accelerated) with virtually no field overtime.