5 Steps to Building a Model Bridge

By on June 11, 2007 -- Modified on October 4, 2016

This ebook, 5 Steps to Building a Model Bridge, answers the most common questions people have about building bridges. In the ebook I outline the steps of building a model bridge, and then walk people through the actual construction of a bridge. The ebook contains many photos and illustrations, as well as 25 bonus tips.

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Download the ebook Downloads: 30908 (application/pdf)

Support the Cause

I am giving out this ebook for free. There is no obligation for you to donate, but please consider helping the cause. You can donate as much or as little as you want. Even as little as $5 helps me to know that you find the ebook helpful. Any donations will go to my time making this website better and so I can continue to make updates to this ebook. The payment is processed through PayPal’s secure servers.





Here is a condensed version of the table of contents:

#1: Know the rules!

  • Be able to define in your own words what the bridge must accomplish
  • Do not get disqualified

#2: Design the bridge

  • Design the bridge around the loading points
  • Choose a truss to use
  • Draw the bridge to scale

#3: Gather Materials

  • Wood
  • Tools
  • Workspace

#4: Build the bridge

  • Step One
  • Step Two
  • Double check for leaning

#5: Testing and Evaluation

  • Testing Procedures
  • Evaluation Procedures

Related Posts:

Post Information

28 thoughts on “5 Steps to Building a Model Bridge”

  1. Thank you for this steps. #ubi #ulticon #ulticonbuildersinc

    By Ulticon Builders Inc -- February 19, 2017
  2. Will your bridge blueprints work with 3/32″ basswood instead of popsickle sticks?

    By Twyla -- February 4, 2014
    • Twyla,

      The blueprints are designed to work with popsicle sticks which are 3/8″ wide. It would be possible to substitute 3/32″ wide basswood sticks, but you will need to make a few minor adjustments on the fly. It is definitely doable, but just know that you will have to do just little extra thinking to make it work well.

      By Garrett Boon -- February 5, 2014
  3. i love this website(:
    thanks for the help i enpjoyed it so much

    By bonnier -- October 21, 2010
    • i agree

      By rerer -- November 26, 2011
  4. Hi Garret

    Nice eBook. However, as a structural engineer I can tell you that you are making some fundamental errors in the ebook. Members taking the largest load does not always need to be the bigger member (for efficiency). This is mistake many young engineers make. Increasing the size of your member actually ‘attracts’ more load and so you achieve the opposite. I would suggest you have an engineer have a look at your ebook.

    Besides that – good work.

    By Menno -- November 8, 2009
    • Hello Menno,

      Thank you for your comment. Unfortunately I have not had the opportunity to take any engineering classes, and base my ebook on my observations from my time spent building model bridges. The ebook wasn’t really meant to be a manual for learning the in-depth engineering concepts that would be useful for building bridges. However, I would love the chance to chat with an engineer about my ebook, and about bridges in general. I always strive to learn more about how bridges work, so thank you for informing me about this phenomena where making a member larger will increase the load acting on it. Do you have any resources where I could learn more about this? Is this something that always happens, or does it depend on the location of the member in the truss?

      By Garrett Boon -- November 11, 2009
      • Great book and website. I do not agree with the previous comment that the larger members “attract” more load. This would be true if stiffness of members were a factor (moment resistance), but since this is a simple truss your assumptions are basically correct: larger loads should have larger members to reduce the stress (force per unit of cross sectional area) — especially the compression members, due to buckling. Thanks

        By Brock -- November 17, 2009
    • This is great! Thank you so much for this resource!!!!!!!!!!!!!!!!!!!!!!!

      By Jared -- May 3, 2017
  5. hi i havent read your ebook yet, but this information is really helpful!

    By Harmony -- October 19, 2009
  6. Enjoyed reading your e-book. There is a small typo on the trusses page where you use the word “implantation” rather then “implementation.” Thought you might want to know.

    I’m wondering if you’ve noticed that there appears to be a ca. 7-8 year cycle in balsa wood strength. This is an observation based on 29-years of balsa bridge contests.

    By Peter -- May 25, 2009
    • Peter, thanks for the comment and pointing out the typo.

      I had not noticed that trend of balsa wood strength that you mention. I have only been working with Balsa for 9 years.

      By Garrett Boon -- May 29, 2009
  7. i did not find this helpful 🙁

    By rose -- February 18, 2009
  8. Garrett,

    Great web page! My daughters and I will be referencing your page as we prepare for this years SO.

    Thanks,
    Tony

    By Tony -- January 27, 2009
  9. G’day,

    I’ve tried to use your “Contact me” form to contact you about some ideas for a bridge i’m building (22grams suppporting min. 25N and dimensions of 648 x 100 x 75mm)

    Is there something wrong with it?

    By Josh -- December 29, 2008
    • Josh, thank you for pointing this out. The contact form did have an error and was not working properly. I have fixed the problem now. If you have any specific questions I will try and answer them. Thanks.

      By Garrett Boon -- December 29, 2008
  10. By using construction methods (joint structure & clamping) from your very helpful site, my son Jackson & I built a bridge using less than 125 Popsicle sticks which supported 500 lbs. and set a new Cub Scout record for our area! Thanks for helping us become the talk of the town!

    By Mark -- December 24, 2008
    • wow, 500 lbs that great. i have built a bridge using about the same number of sticks. mine only held 280 lbs though. Great job. if you dont mind can you tell me what design you used?

      By josh van trump -- January 27, 2009
  11. A big thanks for your publishing such a helpful site. I was not sure where to begin with this project but you have really helped us get started ! Thanks so much for all your efforts

    By our school projict -- November 28, 2008
  12. Thank you so much garrett. You helped me get an A on my project.

    By Kaitlin Lemmert -- November 14, 2008
  13. I would like you to know that this is, by far, the best website on model bridges that I have found. I have been doing intensive research for my engineering technology class, but I find myself coming back to your website over and over again.

    My team and I thank you.

    By ML -- November 12, 2008
  14. You rock! This will definitely help out my science project!

    By anonamous -- November 6, 2008
  15. Wow! This is soo helpful. Everything on your site is. How ever I have been arguing with my dad for quite some time of the reason to use bass and balsa wood. How ever he says that maple is much a better wood for building bridges. Would you agree with him?

    By Cyrus Duong (SO student) -- October 26, 2008
    • Hey Cyrus, I want to put a disclaimer that I have not used maple for building a model bridge. I do know that maple is commonly used to make violins, which speaks for its strength. My question is whether or not you can get maple wood in small enough dimensions to work for a model bridge.

      When I evaluate something, especially for model bridges, I look at several things. For wood, I would compare the following four things to find the “best”:

      Is it efficient?
      Is it a consistent wood?
      Is it readily available?
      Is it cheap?

      Balsa and Basswood fit most of these, but I don’t know about maple. It probably is efficient, but I don’t know whether it is consistent. Balsa wood is definitely NOT consistent, and one must take a lot of care to select good wood. I also don’t know if I have ever seen maple in a hobby store, so I wouldn’t know where to purchase it at. I am pretty sure that it would be more expensive than either Balsa or Basswood.

      By Garrett Boon -- October 28, 2008
  16. THANK YOU! I’m coaching Elevated Bridges for SO this year because my 6th grade son picked it as his first choice. I’m much better with say… reptiles and amphibians! But that’s ok, I feel like it’s all going to be ok because I found your site. THANKS for all of the advice, I’m still reading and trying to grok it all, but it’s the best resource I’ve found for me so far.

    Thanks again,

    n00b Coach Mrs. Klug

    By Mrs. Klug -- October 8, 2008
    • Mrs. Klug, thanks for your comment. And as a former participant in Science Olympiad, I want to thank you for taking the time to be a coach. Especially for an event like Elevated Bridge. There is another resource that you (and your son) will probably find very helpful. It is the Science Olympiad Student Center. It is a forum where competitors from all over the nation talk about ideas and hints. Sometimes the national champions in events will be there offering advice.

      Right now they have a thread dealing with Elevated Bridge that has a lot of good information in it. Here is a link:
      http://scioly.org/phpBB3/viewtopic.php?f=16&t=79

      By Garrett Boon -- October 8, 2008
  17. i am using this in my tech class with my students

    By sabrena -- July 30, 2008

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