Japan spent £15 Billion on an airport Now it’s sinking into the sea

Kansai International Airport in Japan is a major travel hub which serves some of the country’s biggest cities and plays host to millions of passengers a year. Yet there’s a problem.

The airport was welcomed when it first opened in 1994 as a solution to overcrowding at the nearest airport in Osaka – but just 30 years later it’s slowly sinking into the sea. And it’s doing so at such an alarming rate experts have suggested it could be underwater within 30 years.

Kansai came about after it was decided that the region was losing out on trade to Tokyo, and therefore needed a bigger airport.

With the existing local airport – Osaka International – surrounded by densely populated suburbs and unable to expand, two artificial islands were created in Osaka Bay to house the new site, with these linked to Rinku Town in Osaka by a connecting bridge over the water.

Work on this began in 1987 – with Kansai International opening seven years later.

The airport – which serves as a hub for major airlines including All Nippon, Japan Airlines and Nippon Cargo, as well as the low-cost Japanese airline Peach – has survived natural disasters over the ensuing decades and emerged relatively unscathed.

As well as making it through the Great Hanshin earthquake of 1995, it was also hit by a typhoon in 2018 which sent seawater cascading onto the runways.

A few days after the disaster a tanker crashed into the bridge connecting the airport to the mainland, leaving passengers stranded. However, it survived and continued to operate.

Yet the rush to save it is on as it slowly submerges – with the building having sunk 38 feet since it was built.

While engineers knew the airport would sink over a 50-year period they never imagined it would be by this much, instead predicting it would eventually stabilise at around 13 feet above sea level – the minimum elevation required to prevent the site from flooding.

However, the first of the two islands sank to that level within six years.

Although attempts have been made to raise the seawall – spending around £117 million on doing so – some experts have suggested it could be too late to save the airport. In fact, they’ve suggested Kansai could be submerged by the year 2056.

Airport representative Yukako Handa was reported as saying in 2018: ‘When the Kansai airport was constructed, the amount of soil to reclaim the land was determined based on necessary ground level and subsidence estimation over 50 years after the construction.’

The land which was reclaimed for the site has been compared to a ‘wet sponge’, one which needed to be transformed into a dry and dense foundation to support the weight of the airport buildings.

A seawall was then constructed before the artificial ‘islands’ where the airport sits were added.

In an effort to keep the buildings from sinking, workers hollowed out the area underneath the passenger terminals, put plates underneath the hydraulic jacks and hoisted the columns up in stages. However, it’s unlikely to make much difference in the long term.

Construction crews laid five feet of sand on top of the clay seabed to create the foundations for Kansai, as well as installing 2.2m vertical pipes, which were pounded into the clay and filled with sand to strengthen the floor.

The airport remains popular with passengers, receiving approximately 30 million passengers every year.

Although how long it will be able to continue in that manner remains to be seen.