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Bridges

From DT Online

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Description

Bridges were needed to enable us to cross obstacles such as rivers. Trees on river banks often fall of their own accord and 'bridge' across streams. It is quite likely that such natural occurrences gave early travellers the idea to cut down a suitable tree to cross a river.


The word beam describes this basic bridge design and is also an old word for tree - such as found in Hornbeam or Whitebeam for example.


Features and Applications

Naturally occurring creepers which could be slung between two trees might also have provided some early inspiration for an idea which was to become the Suspension Bridge.


Flat stones placed on stepping stones in a stream is another example of an early bridge. As the need grew to span wider gaps and carry heavier loads so did our expertise and ingenuity. Corbel arches developed from this simple starting point, then arch bridges and the idea of cantilever bridges emerged.


Later, the Romans had specialist engineers who designed and built many stone arch bridges including the magnificent Pont du Gard at Nimes which still stands today. More recently, famous 19th century bridge engineers such as Telford, Brunel, Stephenson, Eiffel, Roebling, Maillart and Baker built bridges which are still in use.


Modern bridges exceed even these achievements with examples such as the Humber Bridge, Øresund Bridge, and Millau Viaduct spanning huge distances as result of improved materials and structural techniques.


Media in category ‘Bridges’

The following 19 files are in this category, out of 19 total.