Robbins Slurry TBM Completes Hiroshima Tunnel

Robbins has successfully completed excavation of a 1.4 km tunnel section in Hiroshima, Japan, using a 13.67 m diameter Slurry Tunnel Boring Machine (TBM). This marks the first use of a large-diameter foreign-made slurry TBM in hard rock conditions in the country, overcoming challenges posed by dense granite formations and high water pressures. The project supports the Hiroshima Expressway Line 5, improving urban connectivity and access to Hiroshima Airport.

The TBM was designed and assembled to navigate the city’s restricted site conditions and difficult geology, including granite with unconfined compressive strengths of up to 130 MPa. Special measures were implemented to minimize environmental impacts such as vibration and ground displacement, particularly in residential areas above the tunnel alignment. The successful completion highlights the effectiveness of slurry TBM technology in challenging hard rock environments.

“From the complex machine launch to breakthrough, we are proud of this tunnel being completed for the city of Hiroshima and congratulate the Obayashi-Taisei-Kosei JV. It will make a huge positive impact for the city,” said Shinichi Konda, Robbins Chief Engineer

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