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Introduction
Who can look at the Clifton
suspension bridge, the George Washington bridge, or the Forth bridges, and not think – "How did they do
that?" ?. You only have to see the Clifton gorge, the Firth of Forth,
the Niagara gorge,
the Hudson river, to see some of the problems faced by engineers. And thanks to
them, we
can use the solutions with little effort ourselves.
More clearly than
some other forms of engineering, bridges
can be relatively easy to understand and enjoy. Not many bridges,
especially the more recent ones, have pointless decoration. Even where
surface treatment has been intended, it has sometimes been left
out, as in the cases of the Clifton bridge and the mighty George Washington
bridge, and the Bayonne bridge. But although structure must be governed by function,
one function may be to please people, by
finding a good balance between form and function. Better to be
obscure because inoffensive, than notorious because ugly.
Understanding
Bridges
These pages about bridges try to describe simply the
structures of the most common types of bridge.
For the designers and builders, of course, the
techniques are varied and complex, but the general principles are often
reasonably simple.
Some of the most ingenious
solutions remain hidden inside the structure, under the ground, or in
algorithms and programs of which only the results are visible. Although some bridges, such as
suspension bridges, are easy to understand by sight, others, such as pre-stressed
ones, are not, because parts of the structure are hidden, and of course foundations
are always hidden.
Another
important topic is the appearance of bridges, both in
themselves, and as a part of the town or landscape. Every
structure, however small, contributes to the appearance and feeling of a
place. Each object that is not well proportioned and well suited
to the location represents an opportunity lost. Even small
footbridges, that are not famous, and may never be mentioned anywhere,
can contribute significantly to the impression of a town. Topics are illustrated wherever possible by diagrams or
photographs.
Links
are provided to numerous excellent sites that provide expert knowledge,
statistics, and lists of large and important structures. A short
list of good books is provided, which provide far more detailed
information than this web-site. Some of the linked sites provide much
longer lists of books and links.
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