Toothpick Truss Bridge Project
Name:__________________________________________
Date:_______________
Period:_______________
Purpose:
To design and build a Truss bridge which can be tested for its structural strength
and design.
Instructions:
Each student will research truss bridge designs from the Internet or analyze
actual structures, noting materials used, bracing points and reinforcements, and
how each design takes into account gravitational and load forces. Each student
will then design and build a truss bridge using wooden toothpicks, Elmer's white
glue and construction paper.
Construction:
This is a one or two person project that will be completed in and out of school.
We will research ideas on truss bridge design and construction in school through
the library, laptop cart and computer lab. Some class time will also be given to
design a real-life blueprint scale of the truss bridge. The actual construction of
the truss bridge will take place at home and in the classroom. On test day,
students will test their truss bridge in the classroom to determine its maximum
force load.
Materials:
Here is a list of items that will be provided for you with an explanation of what
it’s used for:
Materials provided:
Purpose:
Graph Paper ¼” grid
Blue Print design
Construction Paper
Roadbed surface
Here is a list of items that will not be provided for you with an explanation of
what it’s used for. These items are to be bought or supplied by yourself and
should only cost a few dollars:
Materials NOT provided:
Purpose:
Toothpicks (wood-rounded) 750ct Bridge members
Elmer’s white glue (small bottle)
Attaching members together (nodes)
Wax paper (25 sqft roll)
Keeps glue from sticking to blueprints
Blueprints and Design:
Along with the construction of the truss bridge, blueprints of the truss bridge
must be provided. The blueprints are going to be scaled to the truss bridge’s
actual size (Scale 1:1). There should be one blueprint for the truss and one
blueprint for the roadbed, each having a side and top view. The blueprints
should have vertical supports, diagonal supports and horizontal supports located
on the bridge for bracing.
Toothpick Truss Bridge Project
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Specifications & Constraints:
1. The total mass of the finished truss bridge must be less than 40.0 grams.
2. The span of the truss bridge is equal to or greater than 10 inches.
3. The width of the truss bridge is equal to or greater than 2 inches.
4. The height of the truss bridge is equal to or less than 5½ inches.
5. The truss bridge members cannot be more than 3 toothpicks thick at any point on the
bridge.
6. A roadbed must be a part of the truss bridge design. Any design can be used
as long as the roadbed is flat and unobstructed so that a matchbox could roll
across the bridge from one end to the next.
7. The only materials that can be used for the truss bridge construction is
wooden round toothpicks, Elmer’s white glue and construction paper for the
roadbed.
8. Excessive amounts of glue may not be used as part of the structure, such as
coating or covering the truss bridge in glue.
9. The truss bridge must be free standing.
Testing the Truss Bridge:
1. Prior to the start of testing, the truss bridge will be checked to make sure it’s within
specifications:*
- The mass of the truss bridge is less than 40.0 grams.
- The span of the truss bridge is equal to or greater than 10 inches.
- The width of the truss bridge is equal to or greater than 2 inches.
- The height of the truss bridge is equal to or less than 5½ inches.
- The truss bridge members cannot be more than 3 toothpicks thick at any point on
the bridge.
- The roadbed is flat, complete, unobstructed, and a matchbox car can roll across the
bridge from one side to the next freely.
- Truss bridge is only made from wooden round toothpicks, Elmer’s white glue and
construction paper for the roadbed surface.
- If left untouched, the truss bridge remains standing without assistance
*Truss Bridges not meeting these requirements may be disqualified from the testing and receive a zero for that part of the project.
2. The truss bridge will be placed over a span that measures 9¾ inches wide.
3. In the middle of the truss bridge, a beam will be laid across the truss bridge’s roadbed
perpendicular to the span. A string will be attached the beam and a bucket will hang
from the string.
4. Weight will be added to the bucket until the truss bridge fails, which is when the weight
falls below a certain level or the truss bridge crumbles.
Toothpick Truss Bridge Project
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Competition:
The lightest mass truss bridge that withstands the greatest force load will be
declared the winner of the competition.
Toothpick Truss Bridge Grading:
Research and Development: (70 points)
 A 1-2 page paper explaining the following: (11 Calibri – double spaced)
o What your truss bridge design looks like, specifically the truss design and
background information on it. The bullets below is just a guide to help
you create your paper:
 Type of truss you are building and what it looks like.
 Discuss the forces acting on the truss bridge
 Who invented it and in what year
 Discuss the people involved in the truss design
 Why was it invented
 Who used this truss design in their bridges (railroads, roads, etc)
 What bridges use this design
 Where are these bridges located
 The results from the Truss Bridge Designer program. (If applicable)
 http://www.jhu.edu/virtlab/bridge/truss.htm
 A small diagram or picture of what the truss.
o The diagram can be hand drawn using a ruler and pencil to scale. (No
Pens)
OR
o A print out of the truss bridge design from an existing bridge or a diagram
found on the internet.
 Make sure that the truss bridge you are printing out is the design
you are going to build.
 The paper must include a works cited page with at least three sources. Follow
MLA format for the works cited.
Blue Print Design: (70 Points)
 A side and top view blue print is required for the truss and the roadbed.
 The blue print must be drawn on ¼” graph paper.
 The blue print must be drawn to the exact scale of the truss bridge being built.
 The blue print must be drawn with a ruler and pencil. (No Pens)
 The blue print must label the pieces of the truss.
o node a, node b, node c, etc…
o member 1, member 2, member 3, etc…
 I highly recommend that you complete a rough copy and submit it to me early so
I can look it over and make any corrections or guidance to complete a final copy.
Toothpick Truss Bridge Project
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Truss Bridge Construction: (100 points)
 The truss bridge is built to the following specifications and constraints:
o The mass of the truss bridge is less than 40.0 grams.
o The span of the truss bridge is equal to or greater than 10 inches.
o The width of the truss bridge is equal to or greater than 2 inches.
o The height of the truss bridge is equal to or less than 5½ inches.
o The truss bridge members cannot be more than 3 toothpicks thick at any point on
the bridge.
o The roadbed is flat, complete, unobstructed, and a matchbox car can roll across the
bridge from one side to the next freely.
o Truss bridge is only made from wooden round toothpicks, Elmer’s white glue and
construction paper for the roadbed surface.
o There are no excessive amounts of glue as part of the structure, such as
coating or covering the bridge in glue.
o If left untouched, the truss bridge remains standing without assistance.
 How well is it constructed?
o Craftsmanship
o Appearance
Testing: (20 points)
 The bridge is scored on a force load to bridge mass ratio.
o This means that the bridge that holds the greatest force load doesn’t
necessarily mean they win the competition.
o The bridge must be light and also hold a lot of weight.
 Scoring will be based off force load to bridge mass ratio from the list below.
o 1st – 5 Bonus Points
o 2nd – 3 Bonus Points
o 3rd – 1 Bonus Point
o 4th to 5th – 20 Points
o 6th to 7th – 19 Points
o 8th to 9th – 18 Points
o 10th to 11th – 17 Points
o 12th to 13th – 16 Points
o 14th to 15th – 15 Points
o 16th to 19th – 14 Points
o 20th to 21st – 13 Points
o 22nd to last – 12 Points
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Results & Conclusion: (40 Points)
 A 1 page paper explaining the following: (11 Calibri – double spaced)
o The outcome of the truss bridge testing and how well it did.
o Where did the bridge fail?
 Which nodes or members broke causing the bridge to fail?
o Any changes you would have done in the process of designing and
constructing the truss bridge to make it look better and hold a larger
force load.
Due Dates:
Research and Development –
Blue Print Design –
Truss Bridge Construction & Test Day –
Results & Conclusion -
TBD
TBD
TBD
TBD
**Dates are subject to change if needed, but will be announced.**
Toothpick Truss Bridge Project
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Toothpick Truss Bridge
Construction Grading Rubric
Name:__________________________________
Date:_______________
Mod:_______________
______/10 points: The truss bridge is completed.
______/10 points: The mass of the truss bridge is less than 40.0 grams.
______/10 points: The span of the truss bridge is equal to or greater than 10 inches.**
______/5 points: The width of the truss bridge is equal to or greater than 2 inches.
______/5 points: The height of the truss bridge is equal to or less than 5½ inches.
______/10 points: The truss bridge members cannot be more than 3 toothpicks thick at any point
on the bridge.
______/5 points: The roadbed is flat, complete, unobstructed, and a matchbox car can roll
across the bridge from one side to the next freely.
______/10 points: Truss bridge is only made from wooden round toothpicks, Elmer’s white glue
and construction paper for the roadbed surface.
______/10 points: There are no excessive amounts of glue as part of the structure, such as coating
or covering the truss bridge in glue.
______/5 points: If left untouched, the truss bridge remains standing without assistance.
______/10 points: Craftsmanship – Truss bridge is built with great skill and expertise.
______/10 points: Appearance – Truss bridge looks nice and time was taken on it.
Total:
______/100 Points*
* If the Bridge receives a ZERO for 3 or more items on the list, the bridge automatically
fails and will receive a 0/20 for the testing part of the project! *
** If the Bridge is shorter than 10 inches, the bridge automatically fails and will
receive a 0/20 for the testing part of the project! **
Toothpick Truss Bridge Project
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Toothpick Truss Bridge
Testing rubric
Name:__________________________________
Date:_______________
Mod:_______________
Mass of the Truss Bridge:
________________ grams
Force load for Failure:
_________________ pounds
Force Load to Truss Bridge Mass Ratio:
Force Load (lbs) ÷ Mass of Truss Bridge (g)
= __________________lbs/g
Class Rank:
 1st – 5 Bonus Points
 2nd – 3 Bonus Points
 3rd – 1 Bonus Point
 4th to 5th – 20 Points
 6th to 7th – 19 Points
 8th to 9th – 18 Points
Class Rank: _________ place
 10th to 11th – 17 Points
 12th to 13th – 16 Points
_________/20 Points
 14th to 15th – 15 Points
 16th to 19th – 14 Points
 20th to 21st – 13 Points
 22nd to last – 12 Points
Toothpick Truss Bridge Project
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