Bridging the Gap

Hadly Eisenbeisz
South Dakota Department of Transportation
STEM Savvy


Report written and submitted by Teen Leader Nevaeh Starr

It might not seem like it, but bridges are an important part of transportation and have been for many centuries. When you think of bridges, you probably think of famous ones like the Golden Gate Bridge or the Brooklyn Bridge. What you might not think about is a bridge that’s close to home. Inspired by Pierre’s Missouri River Bridge and its future remodeling, STEM Savvy invited Hadly Eisenbeisz, a bridge construction engineer from South Dakota’s Department of Transportation, to introduce us to bridge design.

To introduce everyone, the cafe started with an icebreaker. We had to build a bridge using only marshmallows and pretzels. This was a good activity to allow the everyone to learn about each other and to show how much they know about the structure and function of bridges.

After eating a good meal, the teens were ready to learn. Hadly took them on a world tour as they discovered the fascinating history of the first ever bridges and their architectural designs throughout the ages. He explained the basic mechanics of bridges and the incredible ways they defy the weight of gravity. Students learned about beams, arches, trusses, and suspension. Hadly described the complex forces that act on bridges; compression and tension. He used easy to understand examples and hands on activities to show the effect compression and tension has on bridges.

Hands on Activity

Another lesson we learned was on the materials we use to build bridges. Mr. Eisenbeisz made the key distinction between cement and concrete by letting the students make some! They mixed the ingredients that are used to make concrete and made flower pots they could take home.

Making Concrete







To finish up the cafe, Mr. Eisenbeisz  had the students participate in an activity that demonstrates the force of suspension. Four students sat on chairs, supporting the ropes held by four more students. In the middle, a platform sat on top of the ropes. A student would sit on the platform and watch as the platform would stay up in the air!