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Survey holes with W80, Chikushi Tunnel, Japan

Project Description:

Construction of a 11.8 km long tunnel for the Shinkansen high speed train on the Japanese island Kyushu. The sub-contractor, New Japan Development Co., drilled 200 meter, 130 meter and 125 meter long horizontal holes for the purpose of survey and drainage.

Wassara W80 was chosen for its ability to drill fast and produce straight holes. An additional advantage with using Wassara is its ability to handle water in the formation without any detrimental effects on drilling rate.


The survey and drainage holes produced by the Wassara hammers fulfilled the customers expectations to full extent.

Equipment used

DTH hammer Wassara W80
Drill bit 90 mm
Pump Tomec, model JS135E 
Drilling fluid Salt water 
Rig Koken drill boom, Komatsu crawler 
Bore hole length 60 meter vertical and horizontal
Drilling formation Granite