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The Four-Minute Bridge

Engineering Students Build 20-foot Bridge in a Hurry

April 21, 2009

By Russ L. Hudson

Those watching the April 1-4 concrete canoe races at the University of Hawaii may miss the teams of engineering students competing to see who can span a river with a 20-foot-long steel bridge faster than anyone else. It can take mere minutes, according to last year’s time trials held at the American Society of Civil Engineers’ annual Pacific South West Regional Conference. This year’s entry from Cal State Fullerton includes seniors Nick Polichetti, Matt Thompson and Weldon, junior Matt Smith, sophomore Jerome Terrell and freshman Charles Askar.

The conference hosts a bridge building competition along with the canoe races each year to test engineering students’ mettle. Building speed is only part of it. The bridge can flex no more than two inches vertically under a 2,600 pound weight, and no more than one-half inch horizontally under 150 pounds of sideways force.

The number of parts, the size of the team and the weight of the bridge all count in the final score because, in real-world construction, the size of the crew and the materials needed all count as expense. Even how much the bridge flexes is assigned a cost, said team captain James Weldon, senior executive officer of Cal State Fullerton’s ASCE chapter and a senior civil and environmental engineering student. More flexing means more wear.

“In fact,” Weldon said, “if someone drops a nut or bolt or tool into the river — really, it's a big ditch, but it’s treated as a river — it is counted as a loss and the replacement expense is added.”

During the competition, teams bring their parts and materials to a delivery area. From there, teams move parts and tools in precise order to the staging area. Then, when their turn comes, they build their bridge in the construction area.

Cal State Fullerton students began work on this year’s entry the day after last year’s competition, Weldon said. “We’ve put a lot of work into this bridge. Probably 300 hours each, designing and redesigning it, taking it apart and putting it together, over and over.”

“We reduced the number of parts from 60 last year to 20 this year, and we’re using specially shaped plates to bolt down instead of welds. Last year, the winning bridge was built in nine minutes. In practice, we’ve built ours in three minutes and 58 seconds,” a clearly pleased Weldon said.

Cal State Fullerton team of bridge builders learned two other realities of engineering: money and time.

“We raised the money ourselves and we were fortunate to get a number of area fabricators to do our cutting and shaping for us, a lot of it donated. Altogether, we received $45,000 in sponsorships, parts and services for this, including $10,000 from the College of Engineering and Computer Science.

“We’ll pay sponsors back in part by wearing shirts and hats with their logos and in other ways letting people know how much they helped,” Weldon said. “We intend to bring more attention to them by winning, too.”

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