Introduction to Technology

Unit 6: Construction Technologies

WebQuests

Building Bridges

Introduction
Bridges are among the most beautiful structures people create. But all bridges must be functional and safe as well. We use them everyday to cross over streams, railroads, valleys, highways, bays, and even long stretches of ocean. Bridges help us get where we are going faster.

People have built bridges since prehistoric times. The earliest bridges were very simple: Stacked stones or fallen tree trunks served to span short distances over streams and gullies. More than 2,000 years ago, the Romans built many bridges and aqueducts to carry water using the technology of the arch. Early cantilever bridges were built in China and Tibet using wood. The world's first iron bridge was built in the 18^th century. Later, steel and reinforced concrete came to be the materials of choice for bridge builders.

Which type of bridge is best for the various purposes and situations they are designed? How are bridges built today? How have technology and construction techniques changed over time? In this WebQuest, you will explore these and other questions related to bridge, bridge design, and bridge building.

Task
Your job in this WebQuest is to learn about different kinds of bridge designs and how they work. You will also learn about the history of bridge building, and investigate ways bridges have impacted the lives of the people who live near them and use them. You will also learn about some famous bridges and bridge disasters and find out what caused them. Finally, you will answer questions to demonstrate what you have learned about bridges and bridge design.

Process
Read through the following questions. Then research the Internet sites that are listed after them. As you explore each site, look for answers to the questions. Keep a record of the sites where you find answers.

Questions about Bridge Building
1. Since ancient times, engineers have designed three major types of bridges to withstand the forces of nature. What are they?

2. When were bridges first built in the ancient world? What are some of the oldest bridges still in use today?

3. What types of bridges can be found in your community?

4. What is a cofferdam, and how is it used in bridge building?

5. Can you demonstrate how a cable-stayed bridge system works?

6. What are the natural forces that affect bridges as they span the distance between two points?

7. In which American city was the prototype of the famous Brooklyn Bridge built?

8. What would be an ideal location for a steel arch bridge? A suspension bridge?

9. How long is the world's longest bridge?

10. What bridge projects are planned for the future?

Resources
Look at the Web sites given here to find the information that will enable you to answer the questions about bridges, bridge design, and bridge building.

Bridge Basics Visit the Public Broadcasting System Web site to master the basics of bridge design. Take the Bridge Challenge to test your ability to design the best bridge for various real-life situations.
http://www.pbs.org/wgbh/buildingbig/bridge/index.html

Expand Your Vocabulary Check out the Word Bank at Think Quest's Web site and become familiar with the terminology of bridges and bridge design.
http://library.thinkquest.org/CR0210346/history.html

Strengths and Weaknesses Discover the strengths and weaknesses of various types of bridges at this Nova Online Web site.
http://www.pbs.org/wgbh/nova/bridge/build.html

Forces at Work Visit this "How Stuff Works" Web site to learn about compression and tension and the effect of these natural forces on bridges. Follow the links to read about how torsion (the twisting force) is controlled in suspension bridges.
http://science.howstuffworks.com/bridge.htm

Bridge Contest Design a virtual bridge and learn about engineering by participating in the West Point Bridge Design Contest.
http://bridgecontest.usma.edu/

Famous Bridges Visit this site for more information about some of the world's most famous bridges.
http://www.civl.port.ac.uk/comp_prog/bridges1/

Historic Bridges This Web site contains a database of information and photographs about the historic bridges of the United States.
http://bridgehunter.com/

Bridge Disasters You can learn about some spectacular and tragic bridge failures at this Web site.
http://filebox.vt.edu/users/aschaeff/titlepage.html

Dig Deeper This site can link you to great photographs and detailed information about all aspects of the world's most famous bridges.
http://www.oswego.org/staff/abarry/web/famous_bridges_websites.htm

Bridge News Keep up to date on the latest in news about bridges and bridge building at this Web site.
http://bridgepros.com/

Conclusion
In the process of completing this WebQuest, you have learned about bridges, bridge design, and bridge building. You have learned something about the history of bridges and the science behind the natural forces that affect them. You have studied famous bridges around the world and learned about some famous bridge failures and disasters.

As you travel around your community, notice the bridges you cross. Think about the people who designed and built them and how they have enhanced the ability of people to travel and communicate.