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STANFORD -- In crowded cities and suburbs where space is tight and construction disruptive to everyday routines, high-tech animation of contractors' construction schedules offers hope for saving everyone money and anxiety, Stan ord researchers believe.
Their "virtual construction" ideas are being tested at the San Mateo County Health Center, where over the next six years Dillingham Construction Co. of Pleasanton, Calif., is building a new hospital around and within an existin g one.
Throughout construction, the facility must remain operational, which means ambulance driveways cannot conflict with cement truck paths and linens must get from the laundry to patient rooms even as one wing of the old hospital i s converted to new uses and departments are relocated.
Civil engineering graduate student Eric Collier, an architect by previous training, has combined the information contained in hundreds of two-dimensional architectural and engineering drawings and the contractor's master schedu le in an animated three-dimensional computer model of the hospital complex. On a TV or computer screen, viewers can see what various wings, driveways and buildings will look like, from inside and outside, during every week of the six-y ear construction period.
Doctors, nurses, suppliers and others who are not trained to read architectural plans, engineering drawings and contractors' schedules can take a visual walk through the hospital campus as it will change in the future, in order to coordinate their operations with those of the contractor and subcontractors, and vice versa, said Martin Fischer, assistant professor of civil engineering at Stanford's Center for Integrated Facility Engineering.
But the model is also proving useful to construction professionals, who, despite their technical knowledge, consume many hours converting two-dimensional drawings into three-dimensional visualizations in their heads, Fischer sa id. The model makes it faster for them to spot and show one another conflicts early in the planning process, and to see the ripple effect of one change in building plans on other aspects of the project.
Three-dimensional models have been around since early in the computer revolution, but the challenge has been how to make them useful beyond just a replacement for cardboard and glue. Rudimentary models have been used as a sales tool; more detailed models to help visualized mega-projects, such as construction of the several-billion-dollar Boston Artery roadway system. Animated models that can be changed over time as plans change haven't been attempted for sma ller projects, Fischer said, because the costs and time involved in preparing them were generally unknown.
The goal of the Stanford researchers is not to devise new computer-aided-design software but to figure out the scale or level of detail needed to make existing CAD tools cost effective in construction and perhaps also in ongoi ng building maintenance and management.
"Contractors and engineers know how to calculate the hourly cost of preparing engineering drawings, and so they know how much to budget for it in a contract bid," Fischer said. "They don't yet know how to calculate the cost and benefits of putting that same information into a 3-D model. We are trying to help them find out."
The research indicates that modeling, if done at a sensible scale of detail, can be cost effective, even if it can't yet replace paper drawings because of legal record-keeping requirements.
According to some estimates, about 6 percent of labor costs in a construction project are due to mistakes that cause delays, rework and change orders. "Three-D modeling may pay for itself by eliminating some of these costs," Fi scher said.
"With two-dimensional drawings," Collier said, "you might have to check six drawings and compare them in your mind before you notice a discrepancy, say, between the placement of a window and hung ceiling panels. Then you have t o communicate the discrepancy to others by showing them the six drawings." But in building the three-dimensional model, he said, "I have to use all three dimensions - the lengths, heights and widths of everything I model. A conflict between a win dow and the panels will show up in a glance on the computer screen."
During his early modeling of the hospital project, for example, Collier noticed a conflict in the architect's and structural engineer's drawings of a major concrete retaining wall. "In the plan view, the two drawings of the wa ll seemed to agree, but as I began to compare sectional cuts of the wall, it was clear that there was a significant difference in what the two designers intended the wall to be," he said. "One drawing showed the wall three feet thick i n places where the other drawings showed it to be eight inches thick, and one showed it five feet tall where the other showed it fifteen feet tall."
The conflict was cleared up before any concrete was ordered, saving at least $30,000 in extra concrete costs, Collier said. "Many people had looked at these drawings in 2-D and no one had found the conflict. In 3-D, the conflic t could have been seen in a glance."
In another case, Fischer said, the construction manager noticed that heavy equipment was scheduled to be installed in the hospital's central plant ahead of the concrete pads on which to place it. "This is the type of schedule s equencing problem that can lead to delay and costly work change orders when discovered later," Fischer said.
The model also may also save construction foremen communication time if it is used on the site to help instruct work crews. Foremen usually make many drawings on the job in order to give clear directions to their crews, said Fi scher, who, as an engineering student, was once hired as a foreman's assistant to help interpret engineering drawings for workers building Lucile Salter Packard Children's Hospital and a parking garage on the Stanford campus.
"Time explaining things can be cut exponentially if somebody sees a 3-D picture," he said. "For example, the footing subcontractor spent three days with the drawings and was still not certain of what to do. He spent 10 minutes with the 3-D model and understood it."
In the future, a contractor might assemble a three-dimensional model of a building from manufacturer-provided Lego-style models of the project's components - everything from screws to steel girders. Today's computers, however, are not powerful enough to model everything that is visible in a real room, Fischer said, nor would it be cost effective to input the data for each project at that level of detail.
The model that Collier is building includes approximately 25,000 objects, including all the interior and exterior walls, the structural system, facades and landscaping. It also includes some components of the heating, ventilati on and air conditioning system and other equipment. Collier and others spent approximately 1,200 hours on the project, two-thirds of which was spent on the actual modeling.
The hardware and labor costs for the model's construction are estimated to be about $100,000, or about 0.1 percent of the cost of the $100 million construction project, Fischer said.
"A physical scale model of the hospital that was built first cost as much as the computer model - about $100,000 - and it can't be changed without significant added cost, animated or transported as easily," he said.
About a third of the animated model's cost already has been offset by finding ways to avoid construction costs, and another third of the cost is for computer hardware that can be reused by the contractor on other projects, Fisc her said. Contractors also may find that their clients want to buy the changeable model for managing and maintaining a building indefinitely, he said.
As increasingly complete information can be supplied to interested parties before construction begins, Fischer and Collier believe that such models will become a necessity, rather than an option.
"One of the conclusions of our research," Collier said, "is that while limitations still exist, the benefits already outweigh them, not just for the large companies but for almost any construction project."
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