The Shield Tunneling Association of Japan was established in 1999, and its membership consists of 97 companies including leading general contractors, TBM and lining segment manufacturers. Fourteen proven and reliable shield tunneling methods have been registered with the association to date, and the association is helping to apply these shield tunneling methods to various projects and promoting widespread use of those methods.

 In 1939, shield tunneling was used successfully for the first time to construct a circular railway tunnel. In the 1960s, shield tunneling began to be used for various infrastructure projects in urban areas, and the open shield method had its heyday until the 1980s. The period from 1980 to 1990 saw a transition from open TBM to closed TBM such as earth pressure balance shield machines developed in Japan. At present, 98 percent of TBM machines used in Japan are closed type. During the peak period in the 1980s, as many as 300 contracts were awarded each year for shield tunneling work, and marked progress was made in infrastructure development. Today, the number of shield tunneling contracts awarded each year is around 90. However, with a variety of new shield tunneling technologies developed such as the 13 shield tunneling methods.

 A variety of technologies are being developed to promote the utilization of underground space in built-up urban areas. The recent enactment of a new law permitting the use of underground space at depths of more than 40 m below ground surface has accelerated the research and development of new shield tunneling technologies, such as branching and enlargement.

 





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