Model behavior: How to optimize BIM during preconstruction

Gaining momentum: A 2016 survey of 100 global industry members by Timetric Construction Intelligence Center indicates that 49% of respondents employ BIM. (Image courtesy of Visualize the Plan)

Amid growing adoption of 3-D building information modeling (BIM) among owners, designers, and builders, the technology is becoming as deeply embedded in the industry’s firmament as cranes, concrete, and scaffolding. The reasons are many, ranging from clash detection and field error reduction to optimization of schedules, budgets, and building performance. As such, a 2016 survey of 100 global industry members by Timetric Construction Intelligence Center found that 49 percent of respondents employ BIM.

All together: Early involvement of key parties, including the general contractor or construction manager, facilitates more accurate scheduling, cost estimating, clash detection, and visualization, promoting smoother results once construction commences. (Image courtesy of Building in Cloud)

Modeling practices during the preconstruction phase are critical to laying the foundation for activities that occur in the field and, by extension, for the quality of the finished project. “A picture is worth 1,000 words, and a 3-D picture makes it much easier to understand the design intent,” says Nathan Lingard, director of design phase with the suburban Chicago-based office of CM and general contractor Mortenson Construction. With that in mind, what follows are best practices when implementing BIM before the spade hits the dirt.

Who should be on board at the outset of a project implementing BIM?

Because collaboration is key to successfully implementing BIM, involvement of all parties responsible for completion of the project, including owner, architect, consulting engineers, and subcontractors, should occur as early as possible.

“The earlier the general contractor is involved the better,” says Josh Bone, virtual design and construction specialist with BIM supplier JB Knowledge Technologies, who noted that construction management and design-build are among the delivery methods that involve the builder at the project’s inception.

“During preconstruction, we primarily use BIM for planning, scheduling, cost estimating, and visualization,” Lingard says. “The 2-D drawings might show the extent of a glass wall system, but the model helps us understand how challenging it will be to access the wall and actually build it.” Should such insights prove fruitful, expect greater efficiency, fewer delays, less waste, and greater profit during the construction phase.

Resolving conflicts: Once models are combined, users can identify clashes before they occur in the field. This image identifies a conflict with HVAC and plumbing systems in the corridor of a multifamily project. (Image courtesy of JB Knowledge Technologies)

What party should lead the implementation of BIM?

It depends on the size and complexity of the project, says Mike Bellaman, president and CEO of Associated Builders and Contractors. “If the intent is to introduce environmental analysis, energy-cost analysis, and the like into the modeling process, the CM or general contractor would likely be the preferred party,” he says.

Ideally, “the leader should be the party most capable of determining client needs and responding with the appropriate strategy, whether the entity be the architect or the construction manager,” says John Adams, a UK-based industry strategy manager with BIM supplier Autodesk.

The leader’s first order of business: designating a BIM coordinator to steer the project and coordinate activities among consulting engineers and subcontractors, among others, Bellaman says.

What’s the ideal means for laying the groundwork for successful implementation of BIM?

“A savvy owner will ask the designer and builder to address BIM in its RFQ as a means of ensuring they are are well versed in the process and capable of developing and implementing a BIM execution plan,” Bone says.

The execution plan is becoming standard industry practice, Lingard says, adding that Mortenson was at the forefront of developing the concept. “The plan lays out design, management and coordination responsibilities, scheduling, integration, and other key components so that all parties can optimize the model’s development and evolution to minimize rework and streamline the project,” he says.

To facilitate the plan, BIM consultant ENGtech recommends team members acquire 3-D modeling software for creating and manipulating models (Autodesk’s Revit or Bentley Microstation); engineering analysis software (Risa 3D or Tekla Structures); coordination software (Autodesk’s Navisworks or Tekla Structures); estimating software (Timberline) middleware (Innovaya); and detailing software (Tekla Structures or SDS/2).

Prior to modeling, project team members also must develop communications and coordination plans, notes Jason Dodds, director of global construction innovation with ENGworks. For large projects, such as an 800,000-square-foot headquarters, architect Gensler holds coordination meetings with structural and MEP designers once per week, notes Jared Krieger, a senior associate and studio director with the firm. “We go through our coordination list—open items from previous meetings—starting with structural, then overlap between structural and MEP, then MEP alone,” Krieger says. In their entirety, meetings may last up to eight hours, “but we get a ton accomplished,” he adds.

At what point in the preconstruction process should project team members execute BIM?

As early as possible, Bellaman says. “The sooner you begin, the sooner the owner gains clarity in terms of construction costs, lifecycle costs, and the like,” he says. “As a result, the owner can make key decisions in the virtual mode, when they are easier to implement.”

“We begin discussing BIM upon project kick off, and even include it in our proposals” Krieger says. “Because our conceptual design models are fast and sometimes less detailed.”

From the ground up: Autodesk’s Revit is one of the industry’s leading tools for designing a model in 3-D. Its latest iteration, Revit 2017, enhances software performance and helps users better model and communicate design intent. (Image courtesy of Autodesk)

Autodesk’s Formit 360, a tool for the sketch phase, allows the architect to model during conceptual design, with resulting imagery integrated into Revit, Autodesk’s platform for assembling the project in 3-D. “Using sketching programs during the conceptual phase can be highly useful in conveying design intent and performing preliminary estimates,” Bone says.

What are some of the more prominent methods for combining models generated by various parties?

Assuming the 3-D model incorporates Revit—and the majority do, according to Bone—programs such as Autodesk’s Navisworks allows parties to open and combine 3-D models generated in a variety of formats, then review the results with commenting and red-lining tools. The objective: ensuring compatibility among architectural, structural, and MEP systems and identifying clashes among them. “Think of the models as chapters in a book and Navisworks as the proofreader,” Adams says. In practice, each party uploads its model—or “chapter”—into Navisworks, with a designated party assigned to “read the entire book,” Adams says. “It’s a very time-intensive process.”

By comparison, Autodesk’s cloud-based BIM 360 Glue allows parties to review models in real time in a central workplace, facilitating quicker identification of clashes among systems. “Think of 360 as spell check,” Adams says. “It allows designers to address problems much earlier while promoting collaboration among participants.”

Are there protocols for modifying the model as result of clash detection?

It’s most expedient for the parties involved to meet and mutually resolve the issue, Bone says. Should their efforts fail, the contractor may be required to schedule a meeting involving key stakeholders, including the architect. “Meetings may occur weekly, given the large number of clashes we see on projects,” Bones says.

“We regularly conduct virtual design and construction clash-resolution meetings, with the models open and live on the screen,” Krieger says, noting that modifications ideally are implemented before the meeting concludes.

What role do 4-D and 5-D BIM modeling play in the undertaking?

For the uninitiated, BIM 4-D refers to linking 3-D models to software that accounts for time or schedule, allowing parties to envision duration events ranging from lead times to curing and drying of concrete.

Beyond 3-D: BIM 4-D links 3-D models to software that accounts for time and schedule. BIM 5-D links both both time and cost-related information to the model. (Image courtesy of RIB US Cost)

By comparison, 5-D links both time- (4D) and cost-related information to the model, allowing parties to envision construction and corresponding costs over time.

Interoperability among 3-D and 4-D models is readily achievable with 4-D software from Synchro and other suppliers, according to Bone. By comparison, 5-D has proven a tougher nut to crack, Adams says. For its part, Autodesk is collaborating with RIB Software to optimize 5-D modeling for the construction industry.

Any pitfalls to 3D BIM modeling?

“Only that a BIM project is only as good as its execution and communications plans,” Dodds says.