100 Stick Popsicle Bridge: 21″ Howe Truss

The 100 stick popsicle bridge challenge is on. This Howe Truss bridge uses 99 popsicle sticks, spans 21 inches, and holds 200+ pounds. It’s efficiency score is 678. This is an updated version of my old “Popsicle Bridge #3” which was the same length, but slightly different in construction.

This bridge was built from completely un-modified popsicle sticks, Level 1 sorted. I used only Elmer’s White glue to join the sticks together. To test the bridge’s strength I raised the ends up off the ground with wooden blocks, and placed free weights from a weight set on top of the bridge. I did my best to keep the weights centered over the bridge and to place them down gently, and I do not think the bridge broke because of the method of testing.

These three photos show the progression of the bridge breaking. Watch the left side as it starts to fail.

Slow Motion of the Bridge Breaking

My conclusion based on these photos is that the lateral bracing on the left side popped off from the side of the bridge closest to you in the photo. This caused those angled popsicle sticks to twist, and the bottom chord starts to twist a little as well. I think it was a glue joint that came loose and started the chain reaction. The angled sticks on the ends may not have been perfectly even and square with each other, which would have caused a weaker joint.

The other possibility is a weak popsicle stick, which started to fail and then brought the rest of the bridge down with it. I only used a level 1 sort for these popsicle sticks, so this is possible.

Here we have a shot of the bridge holding some weights. Also you will see the analysis of this Howe Truss Bridge as shown by the free Bridge Designer program. This picture shows how the forces were spread out on the bridge at the time it failed. Notice how the forces are concentrated much higher in the middle of the top and bottom chords, as well as on the end angled members. This supports my thought that the left side angled members would have failed first. They were under a very significant load.

So now you have seen the video, and the photo evidence. How do you think the bridge broke first? What would you do to make this bridge better? Keep in mind that I was building under a 100 stick limit constraint.

Build this Howe Truss Bridge

If you are interested, you can purchase the blueprints to build this bridge in my store, and you can also buy a complete kit to build this bridge.

44 thoughts on “100 Stick Popsicle Bridge: 21″ Howe Truss”

  1. I have a limit of 99 popsicle sticks and how can I reasure the sticks so they dont break without going over and I cant break the sticks or they have to stay whole.

    Reply
    • It is called Bridge Designer. It is available for free, but it uses a web technology that is not considered “safe” and is blocked by most browsers.

      Reply
  2. if u could have made the both ends of double riveted joint including lacing with very first truss of both emd. may be it could have more efficiency

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  3. Garret, How much would this Bridge hold if the bridge was held up by a tower of paddle pop sticks 15cm tall? if you haven’t tried this please do so and reply

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  4. Would this bridge work better if each of the sections on top had an X made out of popsicle sticks instead of just some sections with an x?

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    • I believe the failure in this bridge was a bad glue joint on the lateral bracing. Having an X might have helped with that simply because there would have been more joints to get more surface area for the glue.

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  5. if the weight was centerd on the bottom beams rather than plates set on top of the bridge would the weight support be the same or would the amount of weight the bridge is able to support decrease significantly? (significantly meaning more than 25 pounds

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    • Unless there was a local failure, as in the area directly being in contact with the load, then the bridge should hold the exact same amount loaded from the top or the bottom.

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  6. He can i have a posible weight and more info so that i can try to replicate this project for my class studys. And if you have 3d design drawing that would be cool.

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  7. Garret, how much does the bridge weight? I really need this question answered. And if you don’t know… What do you think it would had been?

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  8. Garret, I have to make a Popsicle bridge with 150 Popsicle sticks that spans 60 centimeters. When tested, the load will be centered in the middle (bucket and sand). It has to hold 30 lbs.
    I have tried several times building a bridge with a warren truss, but they all fail. I’m at wits end here, I have to hand it in next week. The bridges I made are all warren trusses (they never give out so far in my experiments), the Popsicle sticks along the bottom and top are all doubled together, the truss is a over truss, I made triangles on the top and bottom, and when I test I use my teachers way; keeping the load at center dangling underneath.
    I know that there is no right way to build a bridge and that you have keep trying and trying. But, Can you please spare me a few tips and what I did wrong?

    Reply
    • Amy, can you clarify what you mean by an “over truss”? I am not sure what that is. From watching your previous bridges breaking, have you noticed any particular weak spot? Are your popsicle sticks breaking first or are the joints failing? Are you sure that both sides of the bridge are perfectly parallel and perfectly vertical? If your bridge is leaning to one side even the slightest amount, it will break easily.

      Reply

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