A new hovercraft service allows passengers to travel to and from the city of Oita on the Japanese island of Kyushu to the city’s airport in less than half the time it used to take. Our engineers worked with acclaimed architect Sou Fujimoto to design three distinctive buildings that facilitate the new hovercraft route, blending advanced engineering with traditional Japanese construction techniques.

A faster journey

Oita Airport has been one of the most inconvenient in Japan for passengers and staff to reach, with a city centre-to-airport bus service taking almost an hour. With the airport’s passenger numbers rising, there was growing demand for a better alternative. The airport juts into the Seto Inland Sea and is positioned across a bay from the city. The Oita Prefecture decided to reinstate a hovercraft service from city to airport, an option that had been available until 2009. Arup and Sou Fujimoto Architects won the public competition to design the new airport and city terminals, as well as a boatyard building fit for modern hovercrafts.

We’re proud that the new terminal buildings are not only making the journey to the airport more enjoyable and convenient for passengers, but also fulfilling a vital function as a designated tsunami evacuation centre for the local community.

Junichiro Ito

Project Director, Arup

Architectural vision

The challenge for Arup was to bring Fujimoto’s remarkable designs to life, within budget and sustainability goals, and make them resilient enough to withstand typhoons and tsunamis. Traditional Japanese timber construction techniques are sustainable, beautiful and keep costs down. Dovetail timber joints minimise the need for additional steel fixings, and locally sourced Japanese cedar has been used as the main material for the airport terminal’s sweeping roof. 

Timber model
Traditional Japanese dovetail joints used to construct the terminal roof

Innovative engineering

On the city-side, the terminal building’s no-wall, steel structure is designed to minimise the extreme force of a tsunami. An innovative, strategic use of both steel and timber columns gives the building its robust structure and, crucially, controls vibration. On the airport-side, we engineered a timber seismic wall at the centre of the building, leaving the south side open for passengers to enjoy the views. The hovercraft boatyard, at 16 metres high, is protected by a reinforced concrete seismic wall that also soundproofs the building, reducing local noise impacts. The boatyard’s roof is made from an elegant space frame system, eliminating the need for columns to facilitate hovercraft access.

BIM model of the hovercraft terminal

2D model of the 'no wall' steel frame designed to reduce tsunami impact

Community value

The city-side terminal is at risk of 4 metre tsunami waves in the event of an earthquake, and keeping the surrounding community safe was a key consideration. Columns support a large flat plate roof, 11 metres above ground, that acts as an evacuation facility and viewing platform. Access is provided by the roof itself, where it slopes down to meet the ground, as well as by an external stairway.

Enhancing the passenger experience

The hovercraft as airport transit is unique in Japan, and the experience is an added attraction for people using the airport. The open and welcoming design of the passenger terminals enhances this. In addition to facilitating a much faster and cheaper journey, they deliver fantastic views out to sea and of the hovercrafts in action. Oita Airport passenger numbers are expected to grow to 2.6 million by 2026. Built to meet this demand head-on, the new terminals are helping to drive better connectivity between Kyūshū and the rest of Japan.

Oita hovercraft terminal
Hovercraft exiting the boatyard adjacent to the city-side terminal building