What is a Toothpick Bridge?

A toothpick bridge exemplifies engineering on a small scale to teach students about structural strength, capacity, resilience, and creativity. In many classes, workshops, and contests, participants build a bridge out of toothpicks that can span a wide river, hold a heavy load, or withstand shaking. By trial and error, they're introduced to architecture, construction, and civil engineering.

One of the best methods of learning is the hands-on approach. Instructors and professors at all levels return to the project that challenges students to build a bridge only with toothpicks. Besides creating a standing toothpick bridge, they may have to fulfill other requirements such as using just two anchor points, only forming triangles, keeping the bridge only so long, etc. The rules also specify if flat or round toothpicks are allowed, what kind of glue to use, and the limit on the number of toothpicks. Competitions award the most supported weight, an unusual design, the lightest bridge, or one that spans the widest length.

A truss is a simple toothpick bridge to build, made entirely from triangles. Triangles are a unique shape because they evenly distribute weight without sheering, unlike squares. A truss bridge uses a series of triangles in two parallel walls that interlock with other triangles. Even young children can complete a truss bridge suspended between two books and test its strength by placing pennies at its center until it collapses.

Other possibilities for a toothpick bridge use other shapes to distribute focused weight. An arch transfers weight to its edges without bending, like a straight brace would. One kind of arch is called a catenary; its inverted curve is made by hanging a chain from two points. Suspension bridges have tall towers that connect long cables to the horizontal road. The towers act as anchors, stiffening the bridge, and taking some tension off the road.

Building any style of toothpick bridge encourages you to expand your knowledge of tensile strength, torsion or twisting, design, load-bearing, cost management, the difference between compression and tension, weight distribution, etc., whether you are an amateur science student or engineering graduate. There are even computer simulations available, where bars represent toothpicks, so students can virtually build and test a bridge without waiting for glue to dry.