Earthquake Memorial Park draws 300,000 visitors, exemplifies impact of bridge's construction The foundation—the soul of the suspension bridge: 15,000-ton steel caissons Bridge firmly supported by century's largest bottom-fixed offshore concrete structures Wind-speed resistance of 78 m/sec. in wind tunnel testing using a 1/100-scale model The longest suspension bridge to survive a magnitude 7.2 quake during construction—technology to share with the world *** Realization of "Dream Suspension Bridge" Key to Future Prosperity in the Kansai Economic Zone ***

The longest suspension bridge to survive a magnitude 7.2 quake during construction—technology to share with the world

On January 17, 1995, the violent shaking of the Great Hanshin-Awaji Earthquake struck the bridge while it was still under construction, and the epicenter of the quake was very close to the bridge. The event occurred after the two main towers had been erected and the installation of the main cables completed, but right before the bridge girders were to be installed. It was seen as an unexpected verification of the structure's earthquake resistance. Surprisingly, the ground that supported the foundation was moved by the great quake, and the length of the bridge was stretched about 1 meter. Aside from that, there was almost no effect on the bridge itself. The Akashi Kaikyo Bridge made history that day as the world's first bridge to survive such severe vertical shocks from an earthquake, midway through its construction. The building of great bridges is the stuff of dreams, and greater visions are already being spun both within and outside Japan. A bridge across the mouth of Tokyo Bay is one such candidate. Elsewhere, plans are brewing for bridges over the Straits of Messina, Gibraltar, and Dover. The Honshu-Shikoku Bridge Authority says, "In view of our achievements in bridging the Akashi Strait, we are willing to offer unlimited technical cooperation." And all the manufacturers involved in the project also seem to share the same sentiment. Sumitomo Heavy Industries' Miyazaki boasts, "Bridges approaching the 3,000-meter class should be possible as an extension of current technology. And if we can take full advantage of the technologies currently under development, the construction of a bridge span approaching the 5,000-meter class might be possible." As fantastic as the schemes of these starry-eyed engineers may seem, one thing they all appear to have in common is an unlimited capacity to wax enthusiastic to interested amateurs about the difficult subject of bridge technology. And with the successful completion of the Akashi Kaikyo Bridge, the world has gotten a taste of the excitement involved in bridging great expanses.

Acknowledgement: SUMITOMOQUARTERLY wishes to thank the Honshu-Shikoku Bridge Authority for its cooperation in the preparation of this article.

The Maiko Viaduct: Another bridge technology straddling crucial transport lines The Maiko Viaduct, a land-based structure on the Kobe side of Akashi Strait, is a 511-meter-long elevated feeder highway that connects to the Akashi Kaikyo Bridge. The Maiko Viaduct is surrounded by a crowded urban district and strides over other important arteries, including the JR Sanyo Line, the Sanyo Electric Railway Line, and national roads. The outbound trains of the JR Sanyo Line alone account for 313 of the passenger trains running right beneath the bridge each day, along with a number of freight and out-of-service trains. To meet the challenge of "implementing safe construction without interrupting traffic on any main thoroughfares," Sumitomo Construction employed a prestressed concrete design and cantilever construction method, both of which are unaffected by topographical factors or traffic conditions. The construction time required was about four years. In the month of August, a total of 1,189,116 vehicles crossed the Akashi Kaikyo Bridge, all of which passed across the Maiko Viaduct on their way to Kobe or Awajishima.