Brilliant Bridges

Brilliant Bridges

Bridging the gap Bridges carry people and vehicles across rivers, roads, railways and valleys. They make it easier to travel from one place to another.

Bridges come in different shapes and sizes. Before a bridge is built, engineers think about what type of gap it's going to cross and what it will be carrying: cars, trains, people or water. Then they work out the best type of bridge for the job and the best materials to use. The Millau Viaduct in France carries a motorway across a wide valley. It's one of the tallest bridges in the world.

Arch bridges The very first bridges were built thousands of years ago. They were fallen trees or stone slabs laid across streams. The bridge takes the weight of the people crossing over. The ground carries the weight of the traffic and the bridge.

These bridges were good for crossing small gaps, but they broke if the traffic was too heavy or the bridge was too long. So, about 3, 500 years ago, the arch bridge was invented to cross wider gaps. The bricks in the arch are shaped to squeeze together and support each other. The arch moves the weight of the traffic and the bridge down to the ground. The ground carries the weight of the traffic and the bridge.

If a stone arch is too wide, it becomes too heavy and falls down. To cross bigger gaps, engineers built bridges with a set of smaller arches. This spread the weight evenly across the structure. Now, they could build much longer bridges. Did you know? The Pont du Gard aqueduct was built in France over 2, 000 years ago. It supplied the city of Nimes with 200 million litres of water every day.