Kansai International Airport, which opened in 1994, was constructed on a manmade island 5 km offshore, in consideration of environmental issues, such as abating aircraft noise, and safety concerns. The challenge envisioned from the beginning of the project was how to promptly deal with the large scale problem of the sinking of the airport island reclaimed from the spongy ocean bed.

Varieties of innovative technologies were introduced in the world’s first airport on the sea, such as measures to protect buildings from the uneven sinking of the ground, which varies according to location. KYB’s Measurement and Compensation System for Uneven Sinking of Structures is one such technology. This system consists of a precision measuring system for uneven sinking and a jack system to compensate for the sinking. This system is installed in the passenger terminal building, which expands 1.7 km in length and occupies 115,000 m2 of the building area.

Imagine a space that expands 2.5 times the Tokyo Dome. The length of the building is the distance between JR Shinbashi Station and Hamamatsucho Station (1.2 km) plus 500 m. The architect for the project commented that it was so large that he had to compensate for the curve of the earth.

About 800 measuring points are scattered over this huge building, and the status of the uneven sinking is automatically measured and the amount required to compensate is calculated automatically. Based on the results of the calculation, multiple movable hydraulic jacks are controlled in harmony to lift the column where a correction is required, and liners (steel plates) are inserted under the column.

This Measurement and Compensation System for Uneven Sinking of Structures is installed in many of the buildings on the airport island in addition to the passenger terminal building. This system supports buildings behind the scenes; a technology that literally deserves the motto of KYB.

Status of ground sinking at Kansai International Airport The average sinking of the island since the beginning of construction to date is 12.3 m. During construction before the opening of the airport, it sank 9.82 m, and during the 10 years since the opening of the airport, it sank 2.48 m. Sinking for the last year was 0.12 m. These values are quite comparable to the results of simulations conducted in the planning of the project and will decline gradually and ultimately stop settling 50 years from the opening of the airport.

Monumental structure of the 20th century The terminal building at Kansai International Airport was awarded the Civil Engineering Monument of the Millennium (for air transportation) from the American Society of Civil Engineers (ASCE). Other monuments selected by them are the Panama Canal, Empire State Building, Hoover Dam; all of them are world-famous structures.

Hydraulic jack sysmtem