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"Dies war mein schönster Entwurf." "It was my most beautiful design." These words appear in Bruecken/Bridges by Fritz Leonhardt, where he refers to a proposed mono-cable suspension bridge. The use of a single cable would probably reduce the tendency to torsional oscillations in wind, but the design was rejected on other grounds. Such virtual bridges must be very common indeed, for many designers will consider several possible designs, often in detail, before choosing the one they consider the best. Designs may also be chosen or rejected by outside bodies that may or may not have expert knowledge.
The cornes-de-vache masonry arch at Over near Gloucester was forced on Telford because the local authorities would not consider the use of cast iron, even though Telford already had a standard design that would have been both adequate and more economic. The Clifton suspension bridge near Bristol was the subject of many entries, some of which were absurd, including one by Telford, who after a lifetime of great achievement had lost his touch. A glass reinforced footbridge was rejected by local opinion in Lechlade, Gloucestershire, because it was deemed "inappropriate" for the surroundings.
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One of the attributes of bridges and other big structures is that they offer the possibility that someone may start to cross, but never reach the other side. For that person, the bridge is virtual. The Clifton Suspension Bridge has been fitted with structures to prevent people from falling from it. In addition it has long been equipped with TV cameras.
On April 1st, 2002, the Golden Gate Bridge Patrol began to operate. Since that date, the number of suicides from the bridge has fallen. Nobody knows the exact number of suicides from the bridge, but it is known to be over one thousand. In the age group 15 to 24, in San Francisco, from 1990 to 1995, only vehicle accidents killed more people than suicide.
On Friday 14th January, 2005, a man apparently jumped from the world's highest bridge, at Millau, only 29 days after its opening on 16th December 2004.
Let's also look at Dogs for the Disabled, Guide Dogs for the Blind, and Hearing Dogs for Deaf People. Each of these dogs becomes a kind of bridge or connection between its person and parts of experience which are normally denied by a disability. These dogs don't just perform a set repertoire of tasks: they also bring new experiences to their person in many unofficial ways. Simply having a dog brings an obligation to get out and exercise it, which may mean outings that would not previously have been made, and offers opportunities for social contact. People will often stop and talk to a person, merely because they have a dog, especially if they are fond of the same breed. Helping dogs have been known to save the lives, or at least the health, of their people by detecting some kind of abnormality, for example in the breathing of an unconscious person, or the preliminary symptoms of an epileptic seizure, sometimes before the person is aware of it.
These types of organizations have sometimes begun in quite unexpected ways. Dogs for the Disabled grew out of the partnership between one person, Frances Hay, and her dog Kim. Mrs Hay was diagnosed as having bone cancer at fifteen years old, and had a leg amputated a year later, radiotherapy having not been able to save it. Mrs Hay continued to live an active life, and her dog Kim, a Belgian Shepherd, was a great help around the home, steadying her when she moved about. As a result of this, Mrs Hay resolved to train dogs to help disabled people. These dogs now perform a wide range of tasks, even including helping people to undress.
Sadly, Frances Hay died in 1990 at the age of 40, but the charity continues to grow. So far over 250 dogs have been trained, and with more income, more dogs could be trained.
The domestication and training of dogs was a great invention. Dogs can be trained to find people in the remnants of avalanches, in collapsed buildings, in any outdoors situation, and they can be trained to find contraband such as drugs and explosives. They can be trained to control farm stock, and to act as guards.
Perhaps the most amazing virtual bridge is one that really does not exist. Suppose you were told that a heavy weight could be carried to a point 1 km away, and only 20 m lower, through apparently empty space, you would want to know how. Yet that is indeed possible with a high-performance glider. The glider builds its own bridge by deflecting the air through which it moves, in a specific way. This requires energy, which is obtained by the loss of height. If a glider has a glide angle of 1 in 40, then it must have a lift-to-drag ratio of 40, and that means it is 97.5 % efficient. Or does it? How do you define efficiency in this case? Most birds travel by actively flying, though many can glide as well. Some glide briefly after every few wing-strokes, while others, such as the wandering albatross, glide almost all the time. The albatross can use the varying wind speed over the waves to travel near the surface with no average loss of height. How does gliding compare with ice skating? What is the minimum slope of ice that would allow someone wearing skates to slide downhill with no effort? What about air-cushion vehicles and lifting devices?
You can probably think of many other forms of virtual bridges.
Some religions and mythologies have included the idea of crossing a river or a sea in order to reach the next world. This is usually achieved by means of a boat or a ship, rather than by a bridge. What do you think is the reason? Even in the 20th century story, "Lord of the Rings", we find the idea of ships to take people to the Grey Havens. A bridge does figure dramatically in the epic, at the point where Gandalf and a balrog fall into the depths in the caverns of Moria.
At the end of Wagner's "Das Rheingold", the gods walk over a rainbow bridge into their home, Valhalla. After three more parts of the Ring, the Valhalla has been destroyed, like the statue of Ozymandias. Security and invulnerability are impossible to achieve. The wall of China, Hadrian's wall, the Antonine wall, the Maginot line, the iron curtain, the Berlin wall, all designed to prevent the passage of people and ideas, did not work in the long run, and, in some cases, did not work at all. Technology, even when backed by violence and terror, cannot prevent change.
The absence of bridges in the mythology of the death passage can be explained logically by the lack of the required technology when the myths arose. But is that the only reason? Death has always been viewed as mysterious and frightening. A bridge would change the whole concept, because it would enable a return journey. Listen to "The Swan of Tuonela" by Jean Sibelius, for an evocation of the darkness of the waters. Strangely enough, some people who have experienced what they believe to have been a near death experience report an opposite feeling - a tunnel of brilliant light.
The emotional difference between a ship and a bridge is marked by the use of the word "she". Some locomotives and airliners have individual names, like ships, but especially for aircraft, this doesn't have quite the same evocation. A very famous aircraft name - "Enola Gay" - was not in fact the real name at all.
If you think that bridge-building is a purely logical and technical business, look into the story of the Skye bridge. Click here for a socio-economic evaluation of the effects of building the bridge, and here for a picture of the bridge. Try to imagine the scene without the bridge. There is an emotional aspect to the idea of an island. Read the words of the Skye boat song, listen to the melody, and try to imagine the length of the boat journey that it depicts. In fact, quite a small change in sea level would result in Skye being joined to the mainland.
Far away in Japan, the main islands have all been connected by great bridges and tunnels, including the world's longest clear span.
Was the design of the Bayonne bridge a purely logical process? Is it a coincidence that its span is very slightly longer than that of the Sydney Harbour bridge? Can you think of any engineering projects, such as individual aircraft, bridges, dams, monuments, palaces, etc, that were motivated by more than economic and logical considerations?
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