Virtual Construction6 Feb, 2007 By: Andrew G. Roe,P.E.
Avoid field problems using digital models
More and more construction teams are using virtual construction to identify potential field problems before they become reality. By using computer tools to build digitally before building physically, designers and builders can identify conflicts between piping, framing and other building components, plus identify scheduling and staging issues.
Virtual construction has been around in various forms for years, but recent software advances are making the practice more commonplace. Some of the early forays were in the 1970s, when nuclear power plant designers developed 3D models of facilities in various stages, introducing a fourth dimension: time. 4D CAD gained a foothold in various building projects in the late 1990s as PC-based CAD became more sophisticated and affordable. The transportation and infrastructure sector has been a bit slower to adopt virtual construction techniques, but that, too, may be changing, industry experts say.
“It used to be so difficult to build [3D] models that you could almost build the real thing faster,” says Dan Gonzales, manager of virtual design and construction for contractor Swinerton of Concord, California. In the last two years, CAD vendors have introduced BIM (building information modeling) tools that “really work,” he says, citing Autodesk’s Revit and Architectural Desktop, Bentley’s Triforma extension for MicroStation and Graphisoft’s ArchiCAD.
Bringing it Together
One of the keys to making virtual construction work is merging data from different sources and different CAD environments. Swinerton uses Graphisoft’s Constructor and JetStream from NavisWorks Ltd., Sheffield, UK, to import CAD data, view composite 3D models, redline changes and publish in various formats. Swinerton is using Jetstream on the Ritz Carlton Highlands Lodge Resort and Spa in North Lake Tahoe, California. The complex includes two main structures connected by an underground pedestrian tunnel, with the main structure housing more than 170 hotel rooms, meeting spaces, an attached four-level parking structure and a 19,000-square-foot spa. Although construction has yet to begin, Gonzales says several conflicts between steel framing and roofing have already been identified and solved, which, without the use of virtual construction, likely would have required field changes.
Contractor Swinerton used JetStream to model a Ritz Carlton resort project. (Image courtesy of Swinerton Inc.)
San Francisco-based DPR Construction claims it detected and solved “thousands of clashes” on the Camino Medical Group office building, a $95-million, 250,000-square-foot complex in Mountain View, California, according to Atul Khanzode, DPR’s virtual building coordinator. Virtual construction is “one of the best technologies for what we do,” he says. The company invested approximately $400,000 in developing virtual construction models for the project, but expects to realize savings of at least twice that amount. Khanzode says he is seeing more specialty designers and contractors doing 3D models, and as a general contractor, DPR’s role is often to combine those models into one.
DPR Construction avoided piping conflicts through virtual construction on the Camino Medical Group office building. (Image courtesy of DPR Construction Inc.)
JetStream can read data from more than 30 different CAD formats and 15 laser-scanning devices, according to Jonathan Widney, NavisWorks president based in Scottsdale, Arizona. JetStream is built around a core engine called Roamer and distributed in four plug-in components: Clash Detective, for identifying physical conflicts; Presenter, for visualization and animation; Timeliner, for linking 3D models with schedules; and Publisher, for publishing images that can be viewed within JetStream or with a free viewer that can be distributed to those without JetStream.
Another developer providing virtual construction software is Common Point of Mountain View, California. The company’s Project 4D allows users to integrate CAD and schedule data and visualize work flows, site access, parking and transportation routing. Project 4D has its roots in a product called InviznOne, developed by Walt Disney Imagineering and researchers at Stanford University. Common Point licensed the technology and now offers Project 4D alongside its ConstructSim product, which derives schedule data from 3D models instead of using schedule data as input. With ConstructSim, Common Point sought “to automatically break up an engineering model and organize it into how it’s actually built,” said Ted Blackmon, the company’s president and former researcher at NASA, where he led development of software used for the Mars Pathfinder mission. ConstructSim is often used on complex industrial and petroleum plants, such as an offshore platform for British Petroleum and the Flint Hills refinery project in Minnesota.
The Flint Hills refinery project used ConstructSim to simulate installation of various components. (Image courtesy of Common Point Inc.)
Roads and Bridges Next?
Regarding the use of virtual construction in transportation and infrastructure projects, Blackmon sees possibilities, but says applying the technology is challenging because “infrastructure work is more amorphous.” Activities such as concrete pours are different from bolt-ups and pipe welds, which often have specific shop drawings depicting their sequence. For now, he sees 4D and virtual construction primarily used for logistical planning on transportation projects such as highways and bridges.
NavisWorks’ Widney says JetStream is being used on several bridges, tunnels, and rail stations and sees similar uses growing as more engineers and contractors discover the possibilities. Projects with complex underground utilities can particularly benefit, he says.