Fri, Mar 6th 2009, 10:58
The Pearl Bridge, or the Akashi Kaikyo Bridge, currently holds the record for the longest suspension bridge in the world, the tallest suspension bridge in the world and is also the most costly suspension bridge building project ever undertaken.
Akashi Kaikyo Bridge links the city of Kobe on the Japanese mainland with the island of Awaii, part of a major highway route to the southern island of Shikoku. The bridge crosses the Akashi Strait, a busy shipping zone prone to extremes of weather, from earthquakes to hurricanes and tsunamis. So, not only is this the longest suspension bridge in the world but it has to stand up to the worst weather conditions.
The construction of the bridge was a major engineering feat ... the quantity of steel cable used on the bridge would go round the world seven times! Construction started in 1988, taking 10 years and 2 million workers.
The Pearl Bridge gets its strength from a complex system of triangular braces fitted beneath the roadway. These braces give the bridge its strength while allowing wind to pass through. The 2 towers supporting the bridge are the tallest bridge towers in the world. They each contain 20 tuned mass dumpers (TMDs) which act to counterbalance the effect of heavy wind.
In 1995 a massive earthquake struck the Akashi Strait, severely testing the construction of the bridge. It resulted in a movement of the 2 supporting towers making the bridge even longer than originally designed. Even though the bridge was not complete it stood up to the effects of the earthquake, giving engineers a real feel for the conditions that the bridge would have to survive under.