1. BRIDGE BUILDING ASSIGNMENT
Work with a partner to construct 1 bridge.
Choose a partner.
Draw a full size truss pattern from one of the six truss examples or you may design your own truss.
Construct the bridge using balsa wood.
Test the efficiency & applied force of the bridge.

2. BRIDGE SPECIFICATIONS
Work as a team to design and construct a balsa wood bridge.
You may use no more than ”x1/8” balsa sticks. (14 ft. total)
The bridge must have two identical trusses, a roadbed & a top.
The bridge must be exactly 10” in length.
The test block must fit between the two trusses.
No excessive glue blobs.
Support weight = 50 lbs. or more
Tape may only be used to hold pieces while glue dries.
Only two pieces of balsa wood may be laminated together.

3. EXAMPLES OF TRUSS BRIDGES

4. UNDERNEATH DECK TRUSS

5. THROUGH TRUSS

6. TRIANGULAR TRUSS

7. K TRUSS

8. WARREN TRUSS WITH VERTICAL SUPPORTS

9. BALTIMORE TRUSS

10. TRUSS BRIDGE INTERCONNECTED TRIANGLES
The truss bridge... consists of an assembly of triangles. Truss bridges are commonly made from a series of straight, steel bars.

11. BRIDGE TERMS WATER ROADBED SUPERSTRUCTURE SUBSTRUCTURE SPAN
ABOVE ROADBED
SUBSTRUCTURE
BELOW ROADBED
RIGHT ABUTMENT
LEFT ABUTMENT
SPAN
WATER

12. Warren Truss with Vertical Supports1 2 3 10 9 8 4 5 6 7 10 9 8 1 2 3 4 5 6 7
Warren Truss with Vertical Supports
Underneath Deck Truss 1 2 3 10 9 8 4 5 6 7
Baltimore Truss 10 9 8 1 2 3 4 5 6 7
K Truss 1 2 3 10 9 8 4 5 6 7
Through Truss 10 9 8 1 2 3 4 5 6 7
Triangular Truss
TRUSS EXAMPLES

13. EXAMPLES OF JOINTS USED IN BALSA BRIDGE BUILDING

15. DO NOT SHADE IN THE LINES!
GRADING PROCEDURE
Lines are drawn with ruler (no wavy lines)
Lines are 1/8” thick.
Appearance of drawing (Easy to read)
Complete wood usage calculations.
Joints are clearly drawn.
GRID SIZE = .25 1 2 3 4 5 6 7 8 9 10
DO NOT SHADE IN THE LINES! 3 2 1
WATER
TRUSS VIEW Drawn by: __________________________________ Block #_____ Date: ____________

16. DO NOT SHADE IN THE LINES!
GRADING PROCEDURE
Lines are drawn with ruler (no wavy lines)
Lines are 1/8” thick.
Appearance of drawing (Easy to read)
Complete wood usage calculations.
Joints are clearly drawn.
GRID SIZE = .25 1 2 3 4 5 6 7 8 9 10 3 2 1
DO NOT SHADE IN THE LINES!
Good joint
Bad joint
WATER
TRUSS VIEW Drawn by: __________________________________ Block #_____ Date: ____________

17. 10
GRADING PROCEDURE
Lines are drawn with ruler (no wavy lines)
Lines are 1/8” thick.
Appearance of drawing (Easy to read)
Complete wood usage calculations.
Joints are clearly drawn.
18.25
15.50
43.75
3.6
7.2
GRID SIZE = .25 1 2 3 4 5 6 7 8 9 10 3 2 1
10”
8.25”
2.25”
2.75” 2”
WATER
TRUSS VIEW Drawn by: __________________________________ Block #_____ Date: ____________

18. TRUSS VIEW DRAWING GRADE
BRIDGES GRADESHEET
TRUSS VIEW DRAWING GRADE
ALL Lines are drawn with a ruler. No wavy lines ____ pts. (20)
ALL Lines are 1/8” thick ____ pts. (20)
Drawing should have neat appearance. ____ pts. (20)
Joints are clearly drawn ____ pts. (20)
Complete wood usage calculations ____ pts. (20)
____ pts. (100)
BALSA BRIDGE CONSTRUCTION
Two trusses must be standing vertically ____ pts. (15)
No excessive glue blobs ____ pts. (15)
Tight joints ____ pts. (15)
Roadbed & top pieces do not over hang trusses. ____ pts. (15)
Over 50 lbs. = 40 pts. 40 – 49 lbs. = 30 pts. Below 40 lbs. = 20 pts. ____ pts. (40)
____ pts. (100)

19. WHAT IS WRONG WITH THIS TRUSS VIEW DRAWING?
WAVY LINES.
LINES ARE NOT 1/8” THICK.
MESSY APPEARANCE.
JOINTS ARE NOT CLEARLY DRAWN.
DID NOT COMPLETE THE WOOD USAGE CALCULATIONS.

20. AN EXCELLENT EXAMPLE OF A TRUSS VIEW DRAWING!
NO WAVY LINES.
LINES ARE 1/8” THICK.
NEAT APPEARANCE.
JOINTS CLEARLY DRAWN.
COMPLETED THE WOOD USAGE CALCULATIONS.