How Bridges are Built and Stay Standing

Study Notes

Cities and towns are built using the same rules as a pretend village, but on a larger scale.
Six-year-old Hannah from the UK asked how some built structures stay standing, specifically wondering why bridges are so strong.
Bridges are designed and built by experts called engineers to span large bodies of water or deep valleys, such as the George Washington Bridge in New York City, which is said to be the world's busiest bridge.
Bridges can be really busy, carrying many people and vehicles, and must be built with strong materials like iron and steel to support the weight.
A simple type of bridge is a beam bridge, which can be as basic as a log or a strip of cardboard between two blocks, but it has its limitations and can collapse under too much weight.
Stronger bridges can be built using certain shapes, such as triangles, which are really strong for building due to their ability to distribute force evenly.
Triangles are often used in bridges, both above and below the deck, in the form of trusses, which help spread out the weight and make the bridge more sturdy and stable.
Another type of bridge is a suspension bridge, which uses tension to spread out the weight, such as the Golden Gate Bridge in California, and is often used to cross wide bodies of water.
Suspension bridges work by using thick cables that stretch from one side to the other, supported by tall towers and anchored on both ends, to create tension and hold up the deck.
The strength of bridges comes not only from the materials used but also from the smart designs and planning of engineers.

Description

Learn how bridges are designed and built by engineers to span large bodies of water or deep valleys, and how they use strong materials and shapes to support the weight. Discover the different types of bridges, including beam and suspension bridges, and how they work.