TRASPORTI & CULTURA N.44
Honshu-Shikoku Bridge Project in Japan by Kazuo Endo
The Honshu-Shikoku Bridges (HSB) were constructed to facilitate transportation between Honshu and Shikoku with expressways and railways, thus contribute to the balanced development of the nation’s land and the economic development. At present, Honshu and Shikoku are connected by 3 routes including 17 long-span bridges as Figure 4 shown, and form one economic and cultural living area over the Seto Inland Sea. The Seto Inland Sea region suffers from very severe natural conditions such as typhoon and earthquake; therefore various technologies were developed when the HSB were constructed. In addition, the environmental assessment was implemented to protect the well-known beautiful natural environment of the Seto Inland Sea National Park. In doing so, special consideration was given so that they are in harmony with the surrounding environment. After the completion of the HSB, they are being maintained and operated in order to keep them in sound state for more than 200 years in a systematic manner because they are playing a vital role in the region and are only routes to connect Honshu and Shikoku. This paper describes the outline, project history, investigations implemented for design and construction and current maintenance of the HSB.
Outline of Honshu-Shikoku Bridges Kobe-Awaji-Naruto Expressway - The Kobe-AwajiNaruto Expressway, the eastern route, connects Kobe City with Naruto City via Awaji Island, and provided an 89 km, 4-lane (partially 6-lane) highway with a design speed of 100 km/h. This route contains two long-span bridges: the world’s longest Akashi-Kaikyo Bridge and the Ohnaruto Bridge. About 45 km of the southern portion including the Ohnaruto Bridge was opened to traffic in 1985, while the remaining northern portion including the Akashi Kaikyo Bridge in 1998. The Akashi-Kaikyo Bridge (Photo 1), which spans the Akashi Straits between Kobe City and Awaji Island, is a 6-lane 3-span, 2-hinged truss-stiffened suspension bridge with a total length of 3,991 m and a center span of 1,991 m. Because of its recordbreaking size, the Akashi-Kaikyo Bridge was carefully designed to withstand an earthquake with magnitude of 8.5 on the Richter scale as well as strong wind of 78 m/s, both which have approximately 150-year return period. The amount of materials used reached to 193,000 ton of steel for the
Il progetto HonshuShikoku Bridge in Giappone di Kazuo Endo I ponti Honshu-Shikoku (HSB) sono stati costruiti per facilitare il trasporto tra Honshu e Shikoku con superstrade e ferrovie, in modo da contribuire allo sviluppo sostenibile ed economico del territorio di questa nazione. Oggi, i ponti Honshu e Shikoku sono collegati da 3 percorsi che includono 17 ponti, e costituiscono una delle più importanti aree di vita economica e culturale oltre il Mare di Seto. La Regione di Seto soffre di condizioni ambientali molto critiche, dovute ai frequenti tifoni e terremoti. Per questo motivo, per la costruzione dei ponti Honshu-Shikoku sono state sviluppate tecnologie appropriate all’ambiente e per garanti della sicurezza. Inoltre, appropriate scelte progettuali sono state sviluppate allo scopo di proteggere il bellissimo ambiente naturale del Parco Nazionale del Mare Interno di Seto. Particolare attenzione è stata rivolta al loro inserimento armonico con l’ ambiente circostante. Dopo la costruzione e il completamento, i ponti Honshu-Shikoku sono mantenuti e gestiti in modo da garantirne una vita di esercizio di almeno 200 anni in modo sistematico, perché essi stanno giocando un ruolo fondamentale nella regione e sono le uniche vie di collegamento tra Honshu e Shikoku. Questo articolo descrive la tipologia, la storia del progetto, gli interventi volti al miglioramento della progettazione e della costruzione e descrive gli interventi di manutenzione corrente dei ponti HSB.
Page across, from top to bottom, from left to right: Hitsuishijima Bridge (far) and Iwakurojima Bridge (near); Shin-Onomichi Bridge (Right Side); Kurushima Kaikyo Bridge; Okayama Great Seto Bridge panoramic view.
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