Mission of the Month: February 2008

Engineering and Bridges

The Essig Stressed Ribbon Bridge in Germany is a suspension bridge..

February 17-23 marks the 55th annual National Engineers Week, so this month’s Mission of the Month is all about engineering, and one type of engineering project — bridges. Engineers take the principles of science and math and apply them directly to making things or solving problems. There are many types of engineers and your lives are touched by their work every day.

Engineers help make things safe. Buildings, roads, bridges, machines, cars, toys, computers, clothes, furniture, food, bicycles, planes, rockets, boats, pens, medicines, replacement joints, artificial heart valves and cell phones are just a short list of what engineers dream up or improve. They design rides at Disneyland and toys like the Slinky. They are involved in every step of these processes from design, manufacture, testing, and repair.Engineering is a field that offers a wide variety of opportunities for careers that are rewarding personally and financially. As you do this month’s Mission, think about your future and whether you might like to be an engineer. Read more about engineering as a career.

Bridges, Bridges, Bridges!

Feeling Tense? Compressed?
Tension (pulling) and compression (pushing) are two of the forces of motion. Understanding them helps us to understand how brides work. Try these simple activities that illustrate the forces at work. Go to the forces activity.

Make a Sweeeet Bridge!
Build a bridge using kitchen materials by applying a few of the things you've learned about forces. It's harder than you think to design and make a marshmallow-and-toothpick bridge.

This beam bridge in Britain carries pedestrians over the road.

West Point Bridge Design Competition
Bridges are very visible example of what engineers do. Many kinds of engineers are involved in building a bridge. They have to solve many problems and consider many factors before a bridge can be built. Bridges are very complex and often beautiful works of art like the Golden Gate Bridge. But how did they become reality?  The forces that a bridge must survive are more complex than just the load of the traffic. If the bridge crosses water, the force of the water pushing against the bridge needs to be considered. What about wind? The Tacoma Narrows Bridge was first opened in 1940 and failed in four months when wind made it collapse. You may have seen film of this collapse. This is what engineers try to avoid.

When designing a bridge, engineers have many choices to make: what materials to use, the shape it will take, approaches to it, environmental factors that will attack its structure (such as salt water on steel), and how the bridge will be used. Cost and appearance must also be considered. Most want bridges that are safe, attractive, and do their job but are also built at the lowest cost. Does this sound like a challenge you would enjoy?

Well, then join in this month’s challenge of the West Point Bridge Design Contest. The contest is sponsored by the United State Military Academy and is designed to give middle school and high school students the opportunity to solve a real problem using engineering principles in the design and analysis of a bridge. Since real-life bridge engineers work in teams, the contest is designed for teams. You can design a bridge online, then submit the design for the contest. The contest uses the West Point Bridge Designer 2007 software that is available for free download. All details are available at the competition Web site. Be aware that this program is a large file, and will take some time to download.


This arch bridge in Japan is hundreds of years old.

The national contest offers no prizes but the top 10 teams in each zone will receive a handsome certificate signed by the contest director. This is a contest for the pleasure of designing a good bridge. Contest Overview and Getting Started

Now that you can build a bridge, join this online competition, sponsored by the US Army Corps of Engineers, to build the best bridge for the smallest budget. All it takes is a download, and a bit of brain power.

Explore previous missions