Nick Dwyer looked all the world like a baker, gently sprinkling flour on kneaded dough.
But in fact he was sprinkling sand into a five-gallon bucket suspended beneath a frail-looking wooden bridge, weighing scarcely half an ounce, that Nick had constructed in his drafting class at St. Thomas Aquinas High School.
While others at the Model Bridge Building Contest at the University of Kansas Edwards Campus looked on Saturday morning, Nick had filled the bucket past the brim with sand. Then he added a couple of weights. Sensing the end was near, he lightly dusted the weights with more sand.
Finally the bridge collapsed with a smart crack, dropping the bucket a few inches to the floor.
Nick, 18, was pleased. His bridge had supported about 79 pounds.
“It performed a lot better than I thought,” Nick said. “I’d never had that happen before. Usually they break pretty quick.”
Nick and about 120 other high school students destroyed a like number of bridges during the contest, which has been sponsored for the last 29 years by the Eastern Chapter of the Kansas Society of Professional Engineers.
Each year the society sends out wood kits and glue to high school students, who then learn about bridges by designing and building their own. But the purpose of the contest is not to find a better bridge design, said Mark Johnston, a bridge engineer who coordinates the program for the society.
“The purpose is to get kids excited about engineering, math and sciences,” Johnston said.
Rick Hetzel, Nick’s drafting teacher at Aquinas, likes the contest and the participation of professional engineers. Hetzel said he has brought students to the contest for 17 years and gives them class time to work out their designs.
“They do this for a grade and they have to get a certain efficiency to get 100 percent,” Hetzel said.
His students did well this year. Ten of the top 11 finishers were from Aquinas. The society will give financial assistance to the top two finishers, sophomores Michael Navikas and Trey Marx, so they can compete in the international bridge building contest in Las Vegas this spring.
Although Nick, who finished fourth, is interested in engineering, he’s really looking forward to a career in education. But anything is possible, he said.
“I didn’t know what it was until I did it,” Nick said. “It wasn’t the numbers crunching I thought it would be.”
The numbers crunching is just what attracted Hudson Davis, a sunny 14-year-old whose sturdy truss bridge weighed a little less than an ounce but supported almost 57 pounds.
Hudson is homeschooled, and math is his favorite subject. His mom found the contest on the Internet and signed him up.
“It’s more than putting a couple of pieces of wood together,” Hudson said. “I learned about all the math that goes into a good design.”
Hudson settled on his design after consulting with Todd Skoog, a family friend and engineer. Even his bridge’s crunching failure held a lesson. Although his two trusses held up splendidly, torque imparted by the suspended sand load eventually ripped apart the crossbeams.
But the pure tactile pleasure of building two models before he glued together his contest bridge on Thursday night was a lesson in itself, Hudson said.
“I had lots of hands-on before I made the real one,” Hudson said. “If you work on it, rather than just think about it, you can see the flaws.”
Hudson finished 13th, the top freshman in the competition.