Kansai Floating Airport That’s Sinking – Can It Be Saved?

Kansai Floating Airport That’s Sinking – Can It Be Saved?

Kansai International Airport, nestled on an artificial island in Osaka Bay, is a testament to human ingenuity and engineering prowess. Opened in 1994, this floating airport was designed to alleviate congestion at Osaka's existing airports and serve as a major hub for international travel. However, despite its impressive design and technological innovations, Kansai Airport is sinking, presenting a daunting challenge for engineers and raising questions about the feasibility of such mega projects.

The Birth of a Mega Project 

Constructing Kansai Airport on an artificial island was a bold and ambitious project. The island, spanning 4 km in length and 2.5 km in width, was created using 21 million cubic meters of landfill. The location was chosen for its proximity to Osaka and the need to minimize noise pollution for nearby residents. The project cost a staggering $20 billion and took over a decade to complete, involving thousands of workers and the latest engineering techniques.

Why is Kansai Airport Sinking?

The sinking of Kansai Airport can be attributed to several factors:

  1. Soft Soil: The island was built on a seabed of soft clay, which has a high potential for settlement. Engineers anticipated some degree of sinking, but the rate has exceeded expectations.

  2. Weight of the Infrastructure: The sheer weight of the airport's infrastructure, including runways, terminals, and support buildings, exacerbates the sinking process.

  3. Natural Forces: The region is prone to natural subsidence and seismic activity, which further complicates the situation.

Since its opening, Kansai Airport has sunk by approximately 13 meters, and it continues to sink at a rate of about 7 cm per year.

Nearby Marinas and Shipping Yards

Kansai Airport's location in Osaka Bay places it near several key marinas and shipping yards, including:

  1. Osaka Nanko Yacht Harbor: A popular marina located to the northeast of the airport, offering berths and services for private yachts and boats.

  2. Sakai Senboku Port: An industrial port to the south, handling a significant portion of the region's commercial shipping and logistics operations.

  3. Suminoe Marina: Situated to the north, this marina caters to recreational boating and small-scale maritime activities.

These facilities underscore the strategic importance of the airport's location for both passenger and cargo transport.

Engineering Solutions and Challenges

To address the sinking issue, engineers have implemented several measures:

  1. Adjustable Supports: The airport's structures are equipped with adjustable supports that can be raised to compensate for the sinking. This solution has been effective in maintaining operational levels but is not a long-term fix.

  2. Regular Maintenance: Continuous monitoring and regular maintenance are essential to ensure the safety and functionality of the airport. This includes resurfacing runways and adjusting terminal buildings.

  3. Reinforcement Projects: Engineers have undertaken projects to reinforce the seabed and stabilize the island. However, these efforts are costly and time-consuming.

Future Plans to Save Kansai Airport

The future of Kansai Airport hinges on innovative engineering and substantial investment. Potential plans include:

  1. Advanced Ground Improvement Techniques: Employing cutting-edge ground improvement techniques to stabilize the foundation and reduce the rate of sinking.

  2. Expansion of Artificial Island: Expanding the artificial island and redistributing weight to lessen the burden on any single area.

  3. New Technologies: Utilizing new technologies in construction materials and methods to create more resilient structures.


Kansai International Airport stands as a remarkable achievement in engineering, yet it also serves as a cautionary tale about the challenges of constructing on unstable ground. While the airport continues to sink, engineers remain committed to finding solutions to ensure its longevity and operational efficiency. As technology advances, there is hope that Kansai Airport will remain a vital gateway to Japan, showcasing human ingenuity's ability to adapt and overcome even the most daunting challenges.