In a world where technology is advancing, the buildings are getting heights and bridges getting longer. The Akashi Kaikyo Bridge is beyond words. It is the world’s longest, tallest, and most expensive bridge to date. The two towers that reach a height of 297 meters above the surface make it the tallest. The bridge’s central span is 1991 meters. The total cost of construction was a whopping 500 Billion yen.
It is now 22 years old and is commonly known as the pearl bring for the view at night. This suspension bridge links the city of Kobe to Iwaya, also crosses the Akashi Strait. The construction began in 1988 and was completed in 1998.
Before the bridge had been built ferries, transported passengers across the Akashi Strait, this waterway often experienced severe storms and other natural calamities. The bridge design enables it to withstand earthquakes up to 8.5 on the Richter scale.
The towers on the bridge were of their current height to anchor the cabling required and to allow boat traffic from below. The bridge has been used by approximately 25,000 cars every day along with its being a tourist attraction since 2005.
Fact: Akashi Kaikyo Bridge was built by the government to make the Akashi strait much safer for travel, as it was the only way to transport people and goods.
Design
The design of the bridge was synchronized, with the structural characteristics of the bridge itself and the surroundings. The anchorages make the enormous structure balanced and aesthetic. Some design features include exclusive shapes and exterior wall cladding. The grey-green paint on the bridge was chosen based on it being modern and blending in with the cityscape.
It took two million workers ten years to construct the bridge.
“Seismic design features of the bridge are quite different and unique when compared to bridges constructed in the past.” (road traffic-technology)
Fact: The bridge design enables it to withstand earthquakes up to 8.5 on the Richter scale. Since this part is much prone to earthquakes, tsunamis, and other natural disasters.
Two dual-hinged stiffening grinders enable the bridge to face any natural calamities. They are located in an area of strong tidal currents. To protect the tower, it has an installation of a filtering layer around the caisson covered with ripraps. The structure can expand or compress anytime and multiple times during the day due to the temperature change. Each anchorage requires approximately 350,000 tonnes of concrete.
Construction and materials
Tuned mass dampers are designed to operate the resonance frequency for dampening forces. This helps to prevent earthquakes. Along with these foundations resist the vibrations caused. There are 1084 main cables in the entire Akashi Kaikyo Bridge along with 1737 illumination lights. These lights are mounted to be displayed on different occasions in patterns depending on their location. Engineers used a complex system to withstand wind which included counterweights, pendulums, and steel-truss girders. Despite these, the bridge still expands and compresses. It was due to these challenges the bridge had the innovation of wind tunnel and cable fabrication.
The foundation depth is said to be that of a 20-storey building. More than a million cubic meters of concrete have been used in construction. Non-disintegration concrete was developed, for better underwater structure. The main contractor was Honshu Shikoku Bridge Authority.
The roadway and the deck are supported by a steel truss. This may make the bridge look less secure but has a strong effect. The truss maintains stability and rigidity while handling the wind pressure.
Fact: Akashi Kaikyo Bridge construction cost is nearly 500 billion yen. This is said to be recovered by the tool that was introduced for vehicles. Since it is also now a tourist spot it is an added source of income.
The main construction material is steel along with reinforced concrete. The rope hangers used galvanized steel wire for high resistance. The beams also used steel for high tensile strength but for keeping it lightweight thus, making it cheaper.
Sustainability
The bridge constructed in 10 years is supposed to last for the next 200 years with very minimal maintenance. This is said, to be done, with the new technology of the Dry injection system. This system prevents corrosion. It is injected to keep constant humidity. To reduce any after sustaining with the exterior a final paint coat was done with a highly resistant fluoropolymer for it to shine and prevent corrosion.
To conclude the Akashi Kaikyo bridge has proved to be a powerful invention in technology and design. It has the integration of engineering taken from over two centuries. After almost 20 years of operation, it remains to be the world’s longest, tallest, and most expensive bridge.
