6) “Breathtaking Bridges”
(Date of Publication = 04 March, 2013)
Structural Engineers face the challenge of designing structures that support their own weight and the loads they carry, and that resist extreme forces from wind, earthquakes, bombings, temperature and others. Bridges, buildings, amusement park rides and many other kinds of projects are included within this specialty. Structural engineers develop appropriate combinations of steel, concrete, timber, plastic and new exotic materials. They also plan and design, and visit project sites to make sure work is done properly. The importance of Civil Engineering can easily be determined by its versatile advancement day by day.
A bridge is a structure built to span physical obstacles such as a body of water, valley, or road, for the purpose of providing passage over the obstacle. Designs of bridges vary depending on the function of the bridge, the nature of the terrain where the bridge is constructed, the material used to make it and the funds available to build it. Following are some famous and versatile bridges around the world.
Millau, France: The Millau Viaduct is an enormous cable-stayed road-bridge that spans the valley of the river Tarn near Millau in southern France. It is the tallest vehicular bridge in the world. At almost 1,000 feet high (taller than even the Eiffel Tower) and over 8,000 feet long, it sometimes sits above the cloud line
Sydney Harbour Bridge, Australia: Sydney Harbour Bridge is one of the Australia’s most well known and photographed landmarks. It is the world’s largest (but not the longest) steel arch bridge with the top of the bridge standing 134 meters (440 feet) above Sydney Harbour. It took eight years to build and opened in March 1932.
Gateshead Millennium Bridge, England:
The Gateshead Millennium Bridge is the world’s first and currently only tilting bridge. But the most amazing thing about this pedestrian and biker crossing of the Tyne River is that it appears as if an eye is winking whenever it is raised and lowered. The Gateshead Millennium Bridge, received the Outstanding Structure Award for being an “an elegan t curved pedestrian bridge with a unique concept of two interconnected arches which rotate to allow ship passage”. This unique award winning crossing has already become a landmark for Gateshead and the Tyne, linking Newcastle’s thriving north bank with Gateshead Quays – the new arts and cultural quarter – to the south. The 105m long tilting bridge is the result of close collaboration between the Structural Engineer and the Architect. The design was dominated by the requirement to retain a clear channel for shipping whilst maintaining a low level crossing for pedestrians and cyclists.
Si-o-se Pol, Isfahan, Iran:Si-o-se Pol (The Bridge of 33 Arches) is a famous bridge in the Iranian city of Isfahan. It is highly ranked as being one of the most famous examples of Safavid bridge design. The bridge is build of bricks and stones. It is 295 meters long and 13.75 meters wide.
Tower Bridge, London:Tower Bridge is a combined bascule and suspension bridge in London, over the River Thames. It is close to the Tower of London, which gives it its name and has become an iconic symbol of London. Construction started in 1886 and took eight years to build. The Tower Bridge was opened on June 30, 1894 by The Prince of Wales. The bridge consists of two towers which are tied together at the upper level by means of two horizontal walkways which are designed to withstand the forces of the suspended sections of the bridge.
Golden Gate Bridge, United States: The Golden Gate Bridge is a suspension bridge spanning the Golden Gate, the strait between San Francisco and Marin County to the north. The bridge took seven years to build, and was completed in 1937. The Golden Gate Bridge was the longest suspension bridge span in the world when it was completed, and has become one of the most popular tourist attractions in San Francisco and California. Since its completion, the span length has been surpassed by eight other bridges. The famous red-orange color of the bridge was specifically chosen to make the bridge more easily visible through the thick fog that frequently shrouds the bridge.
Akashi-Kaikyo Bridge, Kobe-Naruto, Japan: The Akashi-Kaikyo Bridge, also known as the Pearl Bridge, is the “World’s Longest Suspension Bridge“ with a span of 1,991 meters. It is located in Japan and was completed in 1998. The bridge links the city of Kobe on the mainland of Honshu to Iwaya on Awaji Island by crossing the busy Akashi Strait. It carries part of the Honshu-Shikoku Highway. The bridge took almost 12 years to build and was opened for traffic in 1998.
Tsing Ma Bridge, Hong Kong: Massively imposing by day and a twinkling span of lights by night, the Tsing Ma Bridge is an engineering marvel that links Lantau Island to the rest of Hong Kong. The bridge was opened to traffic in 1997 as part of key infrastructure serving the new airport on Lantau Island, and has since become a local sightseeing favourite. As the longest suspension bridge with both rail and road traffic in the world, the Tsing Ma Bridge got its name from the areas at both of its ends: Tsing Yi and Ma Wan. The bridge has a main span of 1,377 metres (4,518 ft) and a height of 206 metres (676 ft). The span is the largest of all bridges in the world carrying rail traffic.
In an age of rapid transportation bridges are very important. By the turn of the century we have seen several bridges that span over such long distances. Man’s desire to reach the ‘unreachable’ and venture new places led him to construct bridges that spanned huge distances and helped him overcome obstacles. A log of wood floating on water might have inspired man to build bridges for the very first time! Thanks to the developments in engineering and architecture, distances could be bridged and seemingly unreachable destinations came within man’s reach.
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