MoDOT breaks bridges to find best model

Southeast Missouri high school students who painstakingly built balsa-wood bridges watched Thursday as state transportation employees broke them.

The day of destruction was part of the Missouri Department of Transportation's third annual bridge-building competition for high school juniors and seniors.

A total of 144 students signed up to try their hand at designing and building the light-weight bridges to withstand being weighted down with sand.

Each student was given 20 pieces of balsa wood, a spool of thread and a bottle of glue to construct their structures. The goal: Build the most efficient bridge -- the lightest bridge to carry the greatest load.

Ninety-nine students' bridges qualified for the competition, nearly three times as many as last year, MoDOT officials said.

"This is our best competition so far," said MoDOT project designer Jason Williams.

Some bridges failed to meet width, height and length restrictions. Bridges could be a maximum of 10 inches wide, 12 inches tall and 20 inches long. Each bridge had to be built to span a 16-inch gap.

The competition was designed to get students interested in civil engineering and to offer students who planned to go into that field help with their education. Five universities, including Southeast Missouri State University, are offering nearly $9,000 in civil engineering scholarships, MoDOT officials said.

The competition, held at Cape West 14 Cine in Cape Girardeau, began at 9 a.m. and lasted until almost 2 p.m.

MoDOT staff weighed down three bridges at a time, placing each on a specially built platform. Each span was set atop metal ends. A long wooden bolt was attached to a wooden car placed on the bridge. A large plastic bucket was hung from the bottom end of the bolt and filled with sand.

When the bridge broke, the bucket of sand was weighed to determine the load it took to cause the damage.

Scott City High School senior Aaron Stewart got the biggest "wow." His bridge with its angled frame took 99 pounds of sand before being pulled down.

Under rules of the competition, MoDOT only counted a maximum load of 80 pounds. But the staff proceeded to add more sand at the urging of Stewart and others in the audience.

"It didn't bend at all," Stewart said.

Stewart said he and his father used the Internet to research the designs of winning bridges in other competitions. He said he didn't use all of the wood provided and used none of the thread.

Although the span handled the most weight, Stewart ended up in second place.

Jeff Rose of Dexter High School had the most efficient bridge. Weighing only 29.6 grams, the bridge withstood a load of more than 52 pounds, MoDOT officials said.

Stewart's span weighed 49.5 grams.

Dexter High School senior Jordan Blankenship didn't get see her bridge break; MoDOT staff already had weighed down her bridge before she arrived at the theater.

Blankenship's bridge, which took her a couple of weeks to build, was designed around a series of triangles to give it strength and stability. It took more than 66 pounds of sand to pull down her bridge.

"Apparently it works," she said.

mbliss@semissourian.com

335-6611, extension 123