Bridge Competition

Objective:

My brother held the school record of 285 pounds for a bridge competition. I am extremely competitive, so I was determined to beat his record, even though the rules were changed after his record to make it harder!

Competition parameters:

• Bridge must be at least 35 cm long

• Bridge cannot dip more than 10 cm below the starting block

• Allowed materials: wood glue, popsicle sticks, cardboard, balsa wood sticks

• Bridge must allow two lanes of Hot Wheel car traffic to cross (at least 4 inches wide)

• Maximum of 300 popsicle sticks

• Minimum bridge weight to hold for full marks was 50 pounds

Brainstorming process:

Based on research on the strongest bridge structure, I chose an arch bridge design. Additionally, I decided to use an interlocking layering design, because I knew that the joints would be the weakest point. Given that the weight would be hooked onto the middle of the bridge, I also decided to build a platform within the bridge for the hook to lay on using vertically rotated popsicle sticks.

Assembly:

I built the side layers of the bridge one layer at a time, with a total of 10 layers on each truss of the bridge, using 296 of the 300 allowed popsicle sticks. Then, I connected the two sides with balsa wood sticks. Finally, I added a cardboard roadway for the Hot Wheels cars to pass over.

Results:

Success! The bridge far surpassed the minimum requirement of 40 pounds, holding an incredible 440 pounds before the provided load block broke under the shaft. There was only damange to the central load beams, so the arch trusses of the bridge could have conceivably held much more. I had broken my brother's all-time school record of 285 by 155 pounds!