What Bridge Design Holds the Most Weight?

What is the strongest bridge design?

This is the question I get asked the most.

Before we can begin to look for an answer, I need to know more specifically what you are looking for. Are you looking for the the strongest Type of Bridge, such as:

Bridge Types:

  • Beam
  • Arch
  • Truss
  • Suspension

Each of these has advantages and disadvantages. Each type could be the best for a specific situation, and there are a ton of factors that engineers must consider when choosing which one to use.

You can learn more about each of these by clicking the link above.

Perhaps you are asking about which truss design is the strongest. Since most model bridges are truss bridges, this is a great question to ask.

Truss Designs:

  • Warren
  • Pratt
  • Howe
  • Many More
Is the the Pratt, Howe, or the Warren truss stronger? Each of these designs, along with the host of variations, was developed for a specific reason or to make better use of existing or new materials or construction methods. Their history is fascinating, and you definitely should check out the articles about each of them.

Each truss design takes a load or force and spreads it out, eventually transferring it to the bridge abutments and/or piers.

So Which Truss is Strongest?

You really are going to pin me down to answering this question, aren’t you?

In my mind, none of these truss designs has an inherent advantage over the others in a very broad and general sense.

However, when we are considering small model bridges, I have a hard time seeing the Howe as efficient as the Pratt. But is one of these better than the most common, the Warren? You can explore my reasoning on this throughout this website.

Why don’t you take a look at each design and comment below which on you think is the best, especially in the context of model bridges.

72 thoughts on “What Bridge Design Holds the Most Weight?”

  1. Girder bridges
    Arch bridges
    Cable-stayed bridges
    Rigid Frame Bridges
    Truss bridges.

    Which one of these can hold the most weight?

    • Thanks for the comment, Brenden. We have a lot more detail in our article database covering a wide range of topics related to model bridge building. One article can’t do it all, so we have things split up to focus on certain things.

  2. Garrett, we recently did a bridge experiment in scouts using card stock to demonstrate how a regular piece will only hold a little weight but the same piece with the long sides folded up a little will hold a lot more. What is the principle being demonstrated? And more importantly, can you use it in Popsicle stick bridge design??

    Any one can try this using the front or back from an empty cereal box.

  3. sweatland@peoplepc.com I am a welding student and have to build a brige 22 inches long 3 inches wide out of 1/8th in rod. the bridge will be tested by how much weight that can be hung on the underside before it collapses. I plan on an arch brige but am trying to figure the best truss system to use for strength. any feedback would be greatly appreciated. ty ben

    • If it is not too late, a good system is to have the support beams extend out from the center to evenly spaced points on the arch

  4. I tested the popsicle stick versions of the howe, pratt, warren, and k bridges. The bridge that withstood the most weight was the pratt bridge.

  5. Does anyone know the strongest type of truss to use for a bridge that will be supporting a hanging a mass in the centre?

    • Usually bridges like the bowstring truss bridge or the double intersecting pratt bridge could hold the most weight, but it depends on what wood you are using. if you are using balsa wood, which is traditional wood for school projects, you would want either triangle or crossing shapes.

  6. im in year 7 and i need to build a bridge that has to be 65cm long, 10cm high. it has to be 200 grams it than has to hold the weight of a road that is 750grams and a trolly that has to be 910grams.(it has to be made from dried spaghetti

    • I am doing an 8th grade science fair project about bridges. How did your project turn out? What type of bridge did you build? How did you do it?
      I am thinking of building a bridge out of spaghetti too. I need to gather data, make graphs. I will vary the length of the spaghetti bridge and keep the weight hanging from the center the same and see how length affects its ability to resist breaking. What do you think? I hope I hear from you.


    • I created an expirement for my fourth grade science fair that tested both the flat truss and the warred truss using the exact same materials; balsa wood and glue. The flat truss held up 46.3 pounds of water, the warren only held 30.9. They both were across a span of eleven inches and in the end I only had chunks of demolished bridge… 🙂

      • LOL. That would be my result!

        What types of materials can you use to make a drawbridge that can hold the weight of many cars at one time?

        I haven’t been lucky enough to see many drawbridges but up in Portland Oregon they are mostly steel (the parts that raise and lower)
        and concrete at the pillars that hold the bridge up.

  7. I am in the 4th grade and have to make a science project about what type of bridge holds the most weight? All new to me and might as well be a language from another planet. Can any one help? Is ther a formula to use?

    • The best design would be a cable-stayed bridge-
      Here’s an image:

      However, I am currently doing a project with material that don’t allow this style of bridge or supports in the chasm, so I’m improvising best I can. I originally intended to attempt a suspension bridge, but have since changed it to an eye-looking thing held by triangles that disperse the weight to either side. I wish I had a picture to show you, but our camera is MIA at the moment.

      I do not know the effectiveness of this bridge yet, and won’t until Tuesday, but feel free to give it a try if this is the type of project you’re dealing with as well.

  8. i am currently workin on a sciencefair project where i will be constructing 3 different bridges.. i am looking for ideas on 1. what 3 designs i should use.. 2. how should I test them as far as which will be able to hold the most weight. and 3 which supplies i should use, hellp mee!

    • i am working on a science project too. i have to design a scale model of a suspencion bridge. but i am not sure how ro build or design a suspension bridge because i am simply a beginner to all of this. what tyoe of equipment should i use?

      • You should probably use balsa wood and wood glue. these materials are really strong and can widthstand a lot of weight.and bridge types such as the parker bridge or the double intersecting pratt bridge are really strong. wow, i feel like a teacher! And im only in 7th grade~!

    • Hello, i see you need help on your science fair project. I know i’m a little late but i’m here to help. You should make three models of bridges use three different trusses and test what one is strongest.

      Your Friend, Juan

  9. Just an observation…The Burr Arch (and King Post) design as used in covered bridges in western Indiana not only allow for distribuation of load, but the archs stiffen the truss and stop twist or deflection that can cause a truss to fail.

  10. i have to construct a bridge that is exactly 7 inches long. i will be given 25 miniature wooden beams that are 7 inches long themselves and i can cut and put the mtogether as i like but i cannot laminate them ( and no not like running them through a lamination machine) using these materials what bridge would have the most strength but would weigh the least?

    • Ralph, I don’t know the modulus of elasticity of a popsicle stick. But I imagine it is not consistent, because of the total lack of quality control with popsicle sticks. For the most part we don’t even know what wood popsicle sticks are made of. Thus, knowing the modulus of elasticity would not really be helpful. What is more beneficial is simply sorting through and finding the popsicle sticks with the best grain and least deformity.

  11. Thank you for not specifing a certain bridge because i know that you would be flamed horribly if someone didnt agree with you. I agree with you 100%! Well Done!

  12. i myself prefer to experimment with combining different desingns and i hav held over 100 pounds on a six ounce bridge withmy technique

  13. Lil Roy, personally I prefer the Pratt truss. I have had good success with it. Do you have to use tubing? Tension members do not need to be anything other than flat pieces of wood. Compression members can be made more efficient if they are in an I or T shape.

  14. In a specific case, such as the truss spanning 15 inches with a single constantly increasing force applied directly in the middle (7.5) inches from the ends, which would be the stronger truss, assuming that a limited amount of material is used. I guess the better question is given a specific amount of material, what is the optimum truss design. Also for the truss members, would a round, square or rectangular tubing be stronger, again the material is limited.


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