West Virginia Tests Bridge of the Future
When Don Weaver saw the bridge deck dangling from a crane, it didn’t look quite right.
The panel being maneuvered into place over the rushing creek near his home was not made of steel or cement, the usual materials used for bridges in his flood-prone rural neighborhood.
“It had these honeycomb tubes running through it,” Weaver said. “It was some wild-looking stuff.”
It was plastic. And Weaver drove right over the small bridge.
“I never thought twice about it,” he said.
But other drivers might, even if the plastic is a high-tech, fiberglass-reinforced material scientists call a polymer. Its trademark name is Superdeck.
“We work very diligently to avoid the word ‘plastic’ because it has the connotation of a cheap product. It is a fiber-reinforced polymer composite,” said co-inventor Hota Gangarao, a civil engineering professor at West Virginia University in Morgantown. “This, in the truest sense of the word, is a composite.”
The recipe for Superdeck includes fiberglass, fabric, carbon fibers and resin. The mixture is pulled through a mold as a liquid and hardens into a lightweight but strong rigid form.
Researchers at WVU say Superdeck is ideal for revamping dilapidated bridges. It’s twice the price of concrete, but it lasts three times longer and won’t rust or corrode. Salt just runs off it.
They say that makes it a better bargain.
Superdeck makes bridge decks one-third as heavy as those built with traditional materials, but three to four times stronger, said William Reeves, executive director of the WVU Research Corp.
The university recently signed a seven-year research agreement with Creative Pultrusions Inc. of Alum Bank, Pa., the marketer of Superdeck. The pact gives WVU a continuing role as the product is tested and put in use.
Approval for nationwide use may take several years, and it may take even longer for contractors and government officials to become comfortable with it, Reeves said.
Jim Sothen, director of the state Division of Highways’ structures section, said he wants to see how Superdeck performs in use, not just in the lab. His agency will erect two more test bridges in West Virginia this year, he said.
“It’s got to kind of prove itself, but we think it has a tremendous amount of potential. Time will tell,” Sothen said. “But at this point, as we go into the 21st century, you’re going to see more use of plastics.
“Bridge engineering 10 years from now is going to be totally different,” he said. “Back in the 1800s, it was wrought iron and timber. Then, in the 1900s, it’s steel and concrete.
“Are we going to go out tomorrow and replace all our bridges with it? No, we’re not. But as the material proves itself, we could start using more of it,” he said.
Robert Sweet, president and chief executive officer of Creative Pultrusions, is confident the product will catch on.
Nearly one-third of the nation’s bridges are dilapidated or too narrow or too weak to carry the traffic crossing them, according to an Associated Press computer analysis last fall.
The review of Federal Highway Administration data found that 182,730 of the nation’s 581,942 bridges were rated deficient as of June 30, 1996. Most aren’t on the brink of collapse; many simply are too narrow to handle current loads.
In West Virginia alone, 45.4% of the bridges are considered substandard.
Creative Pultrusions has three demonstration bridges to test Superdeck, including the one along County Route 26 in Grafton, a meandering 4.2-mile road with 10 small bridges, most of them concrete.
That bridge, erected last fall, is indistinguishable from any other at first glance. The plastic deck is covered with a half-inch layer of concrete, and it sits on steel beams and girders in cast-concrete footings.
The other test spans are in Lewis County and in Xenia, Ohio. Eight more are planned in Pennsylvania, West Virginia and Ohio over the next 12 months, Sweet said. The highway departments in those states have approved the projects.
Superdeck has a life expectancy of at least 50 years, compared with an average of 15 years for concrete. But price will likely determine how popular it becomes.
“It will catch on only if we can keep the cost somewhat in line with concrete and steel,” said Gangarao, who created Superdeck with fellow engineering professor Roberto Lopez.
“Last year, this deck was sold for about $70 a square foot. This year it sold for $50,” he said. Concrete, in comparison, sells for about $25.
That’s a difference of about $12,800 on a 16-by-32-foot bridge.
“I’ve been given the task of reducing the cost to $35 in a couple of years,” Gangarao said. “If I bring it to about $35, I’m pretty sure it will be competitive.”
Sothen said Superdeck could lower the overall cost of bridge construction because a lighter deck means a lighter--and therefore cheaper--support structure.
