Great Bridge Builder Competition

Great Bridge Builder Competition

On December 8th, 4 members of the JerseySTEM Bridge Builder Team participated in a bridge building challenge hosted by Union County College in Cranford, NJ. The girls, 2 seniors and 2 sophomores from local school districts, constructed a 4-ft long truss bridge made of only wooden tongue depressors, dowels, string, and Elmer's glue. The girls participated in an 8 week bridge building crash course in which they were coached by practicing engineers and learned about loads, tension, and compression, as well as about material strengths and construction methods. The overall challenge was to design a bridge that would hold the most weight with the least self-weight, a lesson on efficiency and real life engineering.

The team designed a warren truss bridge and provided a scale drawing to the competition judges, first using pencil and graph paper and secondly using a digital drafting tool. The girls collaborated on different designs and laid out their ideas on the Engineering Encounters Bridge Builder Program, where they took note of failure locations and determined solutions that made the structure stronger such as increasing the size or quantity of the members, especially at mid-span. The girls spent their Wednesday nights gluing the tongue depressors together and installing the dowels to create a structure with 11 joints and clearance for a 4" by 4" block as per the competition specifications. Once the basic bridge was constructed, it was back to the drawing board! The team discussed different methods for making the bridge stronger without adding unnecessary weight. After brainstorming, the girls doubled diagonal members for added redundancy and added flat, horizontal members to create "I-beams" out of the top chords. They also stiffened the structure with X’s on the top of the bridge and reinforced the joints with more glue.

On the day of the competition, the JerseySTEM Bridge Builders joined some 30 other novice bridge teams from high schools throughout the state of New Jersey, all with truss bridges made of the same materials. The girls set up their bridge between two folding tables and quickly the competition was underway. During the preloading round, 2 members of the team began placing 2.5 lb weights on each of the 9 inner dowels, strategically balancing them for a steady load on the structure. With the success of preloading behind them, the team added weights as directed by the competition facilitator to different dowels. Various bridges began to collapse as the load increased. Ultimately, the JerseySTEM team's bridge was one of the last 6 to collapse, carrying 170 lbs before it snapped at one of the middle joints and crashed to the floor. Based on the calculated weight ratio, JerseySTEM came in the top ten for their first year of bridge building!

This challenge was especially unique in that it exposed the girls to the processes of decision making and innovation, providing a hands on learning opportunity with an applicable lesson in engineering. The team learned the importance of adhering to a set of parameters while still thinking creatively to arrive at a competitive solution. This practice in collaboration and team work makes these type of STEM programs worthwhile for future leaders.

Perhaps the most learning came from watching the bridge break! The team already has ideas for building a stronger and more efficient bridge next year, with the current sophomores as leaders and with more students from difference schools. The girls have also provided insight on the experience that will be used to coordinate a bridge program for an even younger generation of bridge builders - at the middle school level. The JerseySTEM bridge builder program is looking to work with sponsors, volunteers, and college engineering students to supply similar lessons and challenges to middle schoolers in underserved communities in Newark and Elizabeth. The JerseySTEM Bridge Builder program is just getting started!

To learn more about volunteering/sponsorship opportunities at JerseySTEM. Please contact: volunteers@jerseystem.org