The Little Balsa Bridge That Could
It was a tragedy. On March 15, 2018, a pedestrian bridge at Florida International University collapsed, resulting in six deaths, eight injuries, and eight crushed vehicles. The disaster was a stark reminder that, no matter how advanced technology becomes, accidents still happen.
In Cornell College’s Engineering Mechanics class, we tackled coursework from both Statics and Dynamics. Because of Cornell’s unique block scheduling, we had to power through both subjects in just eighteen days. As part of the course, we took on a balsa wood bridge project—with a twist. Our teams faced constraints similar to those encountered in the construction of the FIU bridge. The goal was simple: redesign the FIU bridge to hold the most weight using the least amount of materials.
We sketched multiple design iterations in CAD software and analyzed the forces acting on each individual member using simulation tools. After exhausting nearly every popular truss design and seeing the same disappointing results, I had a realization.
“Guys,” I said to my team, “what kind of bridges do we normally drive across?”
“Well… usually they’re flat,” someone replied.
That was it. We quickly mocked up a flat bridge design, ran the analysis, and had a Eureka moment. The numbers showed that our simple structure could hold nearly 250 times its own weight.
Excited, we refined our design—eliminating unnecessary zero-force members and reinforcing high-stress areas. Everything looked perfect… until we saw the other groups’ bridges.
They were massive, intricate trusses that looked straight out of an architecture textbook. With only two days left, my team panicked. Could our flimsy-looking design really hold up? It was too late to change anything, so we braced for testing day.
The first group placed their monstrous balsa bridge on the test rig. It crumpled under 15 kilograms of weight. Then, it was our turn.
We mounted our puny flat bridge between the tables and started adding weight. Our 27-gram bridge needed to hold at least 8,100 grams to earn an A.
At 3,000 grams, the structure groaned.
At 6,000 grams, it started to bow.
At 9,000 grams, it squeaked as if pleading for mercy.
We kept adding weight, and our tiny bridge refused to break. It held 20,520 grams—760 times its own weight. We turned to our professor, asking for more weights. He just smiled.
“Actually,” he said, “I didn’t bring any more. I’m out.”
Engineering isn’t about sticking to the status quo. It’s about practicality. Our tiny, unassuming bridge outperformed every other design in the class. So, I leave you with this thought: What if your lingering doubts in life are like our balsa wood bridge? Stronger than you think? Put them to the test—you might be surprised.