Do you know?

THE KEYSTONE
The keystone is the most important stone in an arch bridge, without this stone the arch would collapse. The keystone holds the arch together.
Draw a stone arch and label the keystone. Explain why the Keystone is very important.

Background
The Arch Bridge is very common. They were built with stone before iron and steel bridges were introduced. A good example is seen in the picture below. The Romans used arch bridges throughout Europe and many of them are still standing today as they are very strong.

Example of a Stone Arch Bridge - Built by the Romans over two thousand year ago. The techniques mentioned above were used to construct this magnificent example of stone arch architecture

The 'Landwasser Viaduct' (Switzerland) an excellent example of a stone arch bridge. Built in 1902 as part of a daring railway track through the mountains. In the photograph the train has just come out of the Landwasser Tunnel. The viaduct has six high arches which carry the train over a river, far below. This bridge was built using revolutionary new methods. Scaffolding was not used, instead steel towers were built and the stone pillars were built around them.

Montreux is a well known city in Switzerland made famous by its scenery and the Montreux Film Festival which takes place every year.
It has one of the best examples of modern viaducts in the world. The viaduct is composed of several arches which carries a busy roadway. Modern building techniques have been used to construct the roadway from reinforced conctrete.

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