Nerdy Notes: The Little Airport That Could

In Japan, land is hard to come by.  Although there’s plenty of if, the majority is in the form of steep-sided mountains (dormant volcanoes, mostly).  This makes it pretty hard to build a new airport—or anything else flat.  Nevertheless, Japan is a bustling, modern nation, and needs airports.  Solving this problem has meant constructing whole new islands and landmasses.

For decades, the industrialized nation has been confronting the problem of a burgeoning population and the need for urban sprawl by taking down its mountains and emptying them into the sea… literally.  Japan’s coastline looks like shards of broken glass—straight-edged peninsulas and islands define the shores of every urban area.  Over the years, landfill—mostly coming from gutted hills and mountains—has extended the shoreline outwards, greatly increasing the total land area of the island country.

In 1987, Osaka—one of Japan’s biggest cities—began an incredible undertaking aimed at giving the city an entirely new international airport without using up any existing land.  If you’ve followed the debacle regarding O’Hare’s expansion, you can imagine how valuable the proposal might be to build a new airport without using anyland.

Kansai International Airport sits on two man-made islands three kilometers out into Osaka Bay. (Image source: http://www.bestnweb.com)

Doing this would mean taking twenty-seven million cubic yards of dirt from the hills surrounding Osaka and building with it a new island three kilometers offshore in Osaka Bay.  Unlike other land reclamation projects, which dredge and heap seabed material, the project to give Osaka a new airport was to consist entirely of material taken from mountainsides and emptied into the ocean.

Three years, eighty soil-bearing ships, and ten-million man hours later, the island which would become home to Kansai International Airport was born.  A massive, rectangular seawall was built, then filled with the excavated soil.  Environmentalists protested loudly, but to no avail.

From 1990 to 1994, workers took up the task of building an airport on the virgin land.  The project involved erecting what was—and is—the longest airport terminal in the world, a large cargo area, and a two-mile-long runway.

Although the project proceeded on schedule, it was hampered by some unique setbacks.  Because dirt and rocks are heavier than water, the large footprint of the airport on the Osaka Bay seafloor introduced a significant weight increase to that area relative to the water which had been there previously.  As a result, the soft seabed compressed, and the airport sank.  Although some compression was anticipated, the novelty of this approach meant that no one really knew how fast or how far the island would sink.  To the chagrin of many, it’s descent toward sea level was quicker and went on longer than expected.  In the first year after the island itself was completed, it sank an incredible twenty-six feet.  The addition of new soil and shoring up of the seawall kept the island above sea-level, but only just.

As the need to keep the island “afloat” became more evident, postponement of work was not an option.  New soil had to be added, or the island would be lost.  As a result, two decades after the plan to build Kansai International Airport was finalized, it became the most expensive civil works project in history, with a total cost eclipsing twenty billion US-dollars.

Kansai’s island was never fully stabilized, and continues to sink very slowly every year.  When—or whether—this subsiding will cease remains unknown.  For the time being, it is slow enough (an inch or two a year) that it will take decades for the airport to be in any real danger.  Heightening seawalls around the property could keep the problem at bay (pun intended) indefinitely.

In the mid ‘90s, many thought of Kansai as an engineering disaster.  They considered its rate of sinking so severe that the airport might have to be abandoned altogether.

Today, almost two decades later, the story has changed completely.  Not only has Kansai managed not to founder, it has proven to be a remarkably resilient bit of engineering.  All of the airport’s buildings are erected on sliding piles and struts, allowing them to be lifted as necessary if the island’s sinking threatens to deform the structures atop it.  This design also made the airport almost impervious to earthquakes.  In 1995, just a year after the airport opened, the Kobe Earthquake struck, registering 6.8 on the Richter Scale and killing thousands in mainland Japan.  Though the epicenter was just twelve miles from Kansai, not a single pane of glass was shattered or beam of metal broken.

In 2003, confidence had grown that Kansai was no longer sinking fast enough to be a problem.  The government made the decision to build an entirely new island parallel to the existing one, for a new runway and expanded passenger terminal.  Although the new terminal has yet to be built, owing to the economic recession, the reclamation project and construction of a second runway went much more smoothly than the first.

Japan has made the most of land reclamation projects; most of its cities' coastlines bear little resemblence to the original geography of the islands, having been extended out into the sea on dozens of man-made peninsulas and islands over several decades. (Image source: Wikipedia)

Across the world, but mainly in Asia, the lessons learned from building Kansai have been put to good use.  Many other airports—several of which are quite large—have been built using similar land-reclamation techniques.  Methods have been developed for forcibly compacting soil, and engineers have a better understanding of what is involved in creating artificial landmasses.

Kansai International Airport created just over four square miles of new land for Japan.  Other airports and reclamation projects have created thousands of acres more.  Although expensive, the benefits of such projects have been proven.  No one’s land has to be taken to build them, they can be designed precisely as needed, and they make room for projects which otherwise seem impossible to bring to fruition.  In crowded, urban areas of the United States, these lessons may be worth looking at.  In the past, the debate has raged over expanding Chicago’s O’Hare International Airport, as has that over building a new airport in far southern suburbs.  What, one wonders, would happen if we were to take the Japanese approach, and build the airport miles out in Lake Michigan?

Editor’s Note: This post was written by Mark Jacobs, an editor at The Jet Fuel Review.  He is an Aviation major, but the left side of his brain is an avid writer.  Mark is a sophomore and will be working a few hours as a tutor in the Writing Center in the 2011-2012 school year.

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