Akashi Kaikyo Bridge 1998

Akashi Kaikyo Bridge 1998

© Shenghung Lin

© Sean Pavone

Akashi Kaikyo Bridge

The world's longest main span suspension bridge

Key Facts

Also known as the ‘Pearl Bridge’

Constructed after two ferries sank in the Akashi Strait

Designed to withstand earthquakes and strong winds


Hyōgo Prefectur, Japan

Across the Akashi Strait

Connects Kobe (Honshu) with Iwaya (Awaji Island)

Designers / Engineers

Honshu Shikoku Bridge Authority

Satoshi Kashima (Lead Designer / Engineer)


Steel truss suspension bridge

1,991m main span

3,911m total length

Main contractors

More than 100 contractors, including:

Mitsubishi Heavy Industries (Steel Superstructure)

Yokogawa Bridge Corporation (Steel Superstructure)


Began May 1988

Opened 5th April 1998

The Bridge

Before the Akashi Kaikyo Bridge was built, ferries carried passengers across the Akashi Strait in Japan. This dangerous waterway often experiences severe storms, and in 1955 two ferries sank in the strait during a storm, killing 168 people. The ensuing shock and public outrage convinced the Japanese government to develop plans for a bridge to cross the strait.

For Japan it’s now a symbol of national pride, and it was the final bridge that united the four main islands. The bridge provides easy access to the island of Shikoku for commerce and tourism.

World's Longest Span Bridges in 1998

Akashi Kaikyo Bridge, 1998, Japan, 1,991m
Humber Bridge, 1981, England, 1,410m
Verazzano Narrows Bridge, 1964, USA, 1,298m
Golden Gate Bridge, 1937, USA, 1,280m
George Washington Bridge, 1931, USA, 1,100m

The Engineering Challenge

Japan experiences some of the worst weather on the planet. Gale winds whip through the Strait. Hurricanes, tsunamis, and earthquakes rattle and thrash the island almost annually. The bridge was designed to withstand winds of 286km per hour (178mph), earthquakes measuring up to magnitude 8.5, and harsh sea currents.

During construction on 17th January 1995 the Kobe area was hit by the ‘Great Hanshin’ earthquake. The earthquakes epicentre was right between the two towers of the bridge which stood 1,990m apart. The seismic event moved the towers further apart by almost a metre, however, as only the towers had been constructed the change was easily accommodated.

Engineers placed 20 tuned mass dampers (TMDs) in each tower. The TMDs swing in the opposite direction of the wind sway. When the wind blows the bridge in one direction, the TMDs sway in the opposite direction, effectively “balancing” the bridge and cancelling out the sway.

© Tomoyuki Hatta

Other long-span bridges