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General Engineering Science Fair Project

Comparing Bridge Strengths

Comparing Bridge Strengths | Science Fair Projects | STEM Projects
We're testing two types of bridges to see which one can hold the most weight. We'll build a suspension bridge and a cable-stayed bridge and then fill a basket with weights until one of them breaks.


The hypothesis is that a cable-stayed bridge will support more mass than a similar built suspension bridge.

Method & Materials

You will build two bridges, a suspension bridge and a cable-stayed bridge, and attach a basket to the middle of the bridges with a harness to support the mass. You will then fill the basket with weights one at a time until the bridge breaks.
You will need 4 balsa wood strips, 4 wood dowels, glue for models, lightweight twine, fishing string, and small weights.


The results showed that the cable-stayed bridges held more mass than the suspension bridges. One suspension bridge broke immediately after one of the vertical suspension strings snapped. The first cable-stayed bridge never broke with the full mass on it.

Why do this project?

This science project is interesting because it tests two different types of bridges to see which one can hold the most weight.

Also Consider

Variations to consider include testing different materials for the bridges, such as metal or plastic, or testing different lengths of bridges.

Full project details

You can find additional information and details for this science fair project here. Have fun exploring!

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