An airport in the middle of nowhere which is slowly sinking cost a staggering The Kansai International Airport serves the Japanese city of Osaka and occupies two artificial islands in Osaka Bay.
When it opened in 1994, millions were excited. Finally, they said, an airport close to our home. Oddly enough that airport has grown further away from the city since it first opened.
That is because each year, the Kansai International Airport has slowly succumbed to the Earth beneath it. It has, in total, sunk 38 feet and counting, yet continues to serve as a hub for All Nippon Airways, Japan Airlines, and Nippon Cargo Airlines which fly all over Asia.
Kansai’s engineers knew the airport was slightly sinking but predicted it to evenly settle over a 50-year period. They said it would stabilise at 13 feet above sea level, the minimum elevation required to prevent flooding in case a breach develops in an encircling seawall.
Within six years, however, portions of the first of the two islands created reached that threshold. Some £117million was spent to raise the seawall, but some engineers believe it is too little too late.
Predictions now put Kansai’s demise as occurring by 2056, when sections of the two artificial islands may well sink more than 13 feet to sea level. The airport is built on reclaimed land, land that is essentially like a wet sponge. Before it is able to support the huge weight of something like airport buildings, this land must be transformed into a dry, dense foundation.
To achieve this, construction crews laid sand five feet deep above the cay seabed, the installed 2.2 million vertical pipes, each nearly 16 inches in diameter.
Once the pipes were pounded into the clay, they were filled with sand which absorbs moisture from the surrounding soil and layers beneath. Heaps of soil were then dredged and brought into the area, squeezing into the ground layers to create a stiffer floor.
A seawall was then built and the rock consolidated, and before long, the artificial mounds on which the airport would sit were finished. To save the airport from the sea, workers excavated below the passenger terminal, inserted plates beneath the hydraulic jacks, and raised the columns in stages.
Yet, even with these corrective measures, the airport is likely to continue sinking. Engineers are not only concerned about the rate of sinkage but also the fact that Kansai isn’t actually even. It means parts of the airport are sinking at different rates.
The centre of the airport, for example, is thought to be sinking quicker than the speed recorded at the ends of the building. While it has cost a pretty penny, Kansai has served its purpose and continues to connect Osaka, Japan’s third biggest city, to the world.
In 2016 alone, more than 26 million people used Kansai, making it among the 30 busiest airports in Asia. For how long that may last, however, is anyone’s guess.
