Different Types of Bridge Construction
Teacher: Technology Education Student
Time Requirement: Two 50-minute class periods
Age Group: 9th – 10th grade level
Behavioral Objectives: At the end of this lesson, the learner will be able to:
1. Distinguish between the four different types of bridges.
2. Describe the key feature of the four different types of bridges.
3. Define the two major forces that are present in ever bridge. (compression and
4. Construct a scale model of one of the four types of bridges based on certain
specifications given to the. (i.e. total span, materials given, etc.)
I will ask the students how their lives would be different without the use of
How do bridges affect them directly? What would happen to all of the goods that
are shipped and driven across major bridges? How would they travel to work in
the morning? What would be different about highway systems?
Presentation of New Material:
1. There several forces that act on a bridge at any given time, but the two most
important forces are called compression and tension.
A. Compression: This is the force that when applied to a bridge
compresses, or shortens, the bridge.
B. Tension: This is the force that, when applied to a bridge,
expands or lengthens the bridge.
* These definitions will make more sense when we begin talking about the
different types of bridges. (Option: Use the example of a spring being
compressed and pulled.)
2. There are 4 major types of bridges:
A. Beam Bridges
1. This is the simplest and the most inexpensive type of bridge.
2. Beam Bridges are considered the “vanilla of the bridge
world”. (Craig Finley of Finley/McNary Engineers.
3. A beam bridge is simply a rigid horizontal structure that is
resting on 2 piers, one on each end of the bridge.
4. They may have more that two piers.
5. The farther apart their piers, the weaker the bridge becomes.
6. Pre-stressed concrete is used to build most beam bridges.
- It is very cheap, and the steel rods imbedded in it makes
B. Arch Bridges
1. This is one of the oldest types of bridges.
2. Instead of pushing straight down, the weight of the arch
bridge is carried outward along the curve of the arch to the
supports at each end.
3. They are made out of steel and pre-stressed concrete, which
increases the span of the bridge.
4. Discuss the Natchez Trace bridge in Tennessee.
- This is a revolutionary bridge because there are no
spandrels (the vertical members that send the load to the
C. Suspension Bridges
1. This type of bridge is the most expensive to build, yet they are
able to cover the greatest distances.
- They are able to span up to 7,000 ft.
2. In order to construct a suspension bridge, the cables are strung
across the river, and then the deck (or road) is suspended
from these cables.
3. The cables are made of thousands of strands of steel bound
and twisted together.
D. Cable-Stayed Bridges
1. A cable-stayed bridge is much like a suspension bridge.
- Both roadways suspend from cables.
- Both of them have towers.
2. A cable-stayed bridge is different because the roadway hangs
from the cables that are connected directly from the tower to
3. These bridges require less cable than a suspension bridge.
4. They also create an unobstructed view of the land the bridge
is traveling over.
Upon completion of the new material, the students will be given a quiz.
During the next class period, a handout will be passed out with a description of
the project that they will be doing. (See a copy of the handout attached at the end
of this lesson plan) The project is one in which the students will be given the
opportunity to build a bridge out of given toothpicks and glue, and upon
completion of the projects, a contest will be held to see which bridge withstands
the most weight.
At the end of the first day, the closure will tie everything together and review all
of the information that was presented in the lesson. This closure will help the
students with the quiz at the end of the lesson. Once the project sheets have been
handed out, closure will reaffirm all of the options that the students should
consider for their own bridges. Finally, at the end of the unit, I will tie this unit
into whatever the next unit should happen to be.
1. Students will complete a quiz at the end of the first class period.
2. Students will construct a bridge using toothpicks and glue, showing that they
understand the key concepts about bridges.
3. Students will write a brief one-page reflection discussing the problems that they
faced when building their bridges and how they overcame these challenges.
1. Computer with Power Point software and internet access
2. Printed quizzes
1. Nova Online, Super Bridge webpage:
2. Project scenario adapted from Building Big website:
3. ITEA (2000). Standards for Technological Literacy: Content for the Study of
Relationship to Standards:
Standards for Technological Literacy: Content for the Study of Technology
1. Standard 4: Students will develop an understanding of the cultural, social,
economic, and political effects of technology.
2. Standard 8: Students will develop an understanding of the attributes of design.
3. Standard 9: Students will develop an understanding of engineering design.
4. Standard 10: Students will develop an understanding of the role of
troubleshooting, research, and development, invention and innovation, and
experimentation in problem solving.
5. Standard 11: Students will develop the abilities to apply the design process.
6. Standard 18: Students will develop an understanding of and be able to select and
use transportation technologies.
7. Standard 20: Students will develop an understanding of and be able to select and
use construction technologies.
Different Types of Bridge Construction
Name: ___________________________ Date: ___________
1. Name the two most important forces present in bridges at all times.
2. What are the 4 major types of bridges?
3. Which type of bridge is this a picture of?
You’re here just in time! The citizens of Craggy Rock, a growing
community, are in dire need of a bridge to connect it to the city across the
river. The community is in need of a bridge quickly, and these people know
what they want!
Due to the fact that you are experts in the area of bridges, they have
asked each of you to come up with a design, and they want to see a miniature
model made entirely out of only toothpicks and glue!
The people of the community will choose the best design based on
home much weight the bridge can hold on only two piers. In our case, the
bridges will be tested by placing each end on two tables that are placed 50
centimeters apart. Weights will then be added to the center of the bridge
until the bridge breaks. The one that holds the most weight wins!
You will be given an unlimited number of toothpicks and as much glue
as you would like, but these are the only two materials you may use.