Kansai aerodrome generally processes 920 flights and over thirty million passengers. A year swell after you think about it’s already sinking below the stormy waters of the Bay of Osaka.
How did engineers pull it off in just four years?
Is long could it put up with the looming threat of rising sea levels?
How Japan built the world’s largest floating airport?
During the 1980s the city of Osaka and its surrounding area was undergoing a crisis. Rival city Tokyo was attracting tourism the bumper slides with the national export business thanks in no small part to its shiny new Narita International Airport. Osaka’s Itami airport by contrast was aging badly and hemmed in by densely populated suburbs, making any expansion impossible.
In Japan where something like 80% of all land is mountainous in character, flat places to build things like airports on or at a premium about almost always densely populated, even if the Japanese government was in the mood to snatch land off landowners for the greater good experience building Narita airport where bitter protests against the Tokyo project led to thousands of arrest at 7 deaths make this a nonstarter, so for the city of Osaka to develop new air capacity it had to start thinking outside the box.
Japanese city planners had flirted with artificial islands in the past to make up the limited land availability during the economic boom years of the 60s. But to build an island on the scale needed for a major International Airport would require a different magnitude of ambition and ingenuity all together.
Moreover, the bay of Osaka is notorious as a center for deadly seismic activity. It is also prone to unpredictable and destructive typhoons. Apart from disruption to fishing lanes, wisely settled early with a binding payout to the local fishing community, a crack team led by starchitect Renzo piano famous for designing the Pompidou center in Paris and the Shard in London sent to work directly. The site was selected 3 miles out to sea at a depth of around 60 feet below which looked like a layer of soft alluvial clay.
This material is familiar to marine engineers but at this distance from shore, a significantly trickier base layer of diluvial clay around 1000 feet thick would need to be tamed to support the entire airport, using core sampling techniques and educated guesswork civil engineers estimated the airport island might sink into this goofy mess anywhere between 19 and 25 feet before ultimately settling.
in the interests of cost-cutting project leaders cross their fingers and hope for only 19 feet of sinkage then gingerly they proceeded with the built-in order to strengthen those soft play layers around a million pipes were drilled deep into the sea bed these were then filled with sand and the pipes removed leaving a million or so sand columns to absorb the moisture from the surrounding sponge-like clay. Then it would hopefully settle and support the weight of the airport.
2 1/2 years since the project started in 1989 it was time to stuff the gap in the middle of the walk with enough soil to fill it.
2 years later, the colossal 4000 tonnes 500 feet bridge modules were lifted into place. The bridge along with a highway on the top deck and a railway down below is two miles long and costs over a billion dollars. The bridge design incorporates clever flexible joints a smart move by engineers concerned about the future impact typhoon winds might have over the lifetime of the structure.
The terminal building rented in the shape of a segment from a giant toroid is covered in some 5000 panels of glass each set within a rubber frame so as not to shatter in high winds on the roof there are 90,000 stainless steel tiles painstakingly installed by hand and tested to bear the stresses and strains of a major earthquake or typhoon.
The huge internal spaces elegantly spread over 4 stories, it can be access land by car train or hydrofoil and is studded with 41 gates each no more than 90 seconds travel from the terminal concourse proper. That 100-foot high ceiling is designed with a curve in the top to minute patterns of air circulation and thus support fresh air flow, these colorful mobiles Bob about in the invisible walls and eddies to give you an idea of how breezy it is up there.