The excavation of a 3.3-kilometer-long drinking water tunnel with segmental lining and an inner diameter of 3.7 meters for the "Seventh Bangkok Water Supply Improvement Scheme" posed some real challenges. The EPB3776AH by Herrenknecht mastered the challenges with bravoura. A street, a section of rail track and a klong (canal) had to be crossed under avoiding disturbances or even damages above ground.
To pass under the street, the EPB machine turned at an angle of 90 degrees and drove under 20 concrete pillars. On the route ten tight cruves with radii of between 79 and 635 meters had to be mastered. The defined maximum horizontal and vertical deviation of +/- 40mm was maintained with the help of the navigation system "LNS-S". With an exactly controlled pressure of at least 1.5 bar at the tunnel face, the risk for heave or settlement could be successfully eliminated. A rail system was installed in the tunnel for the transportation of segments and muck.
With the breakthrough on March 12, 2003, a challenging tunnel project was led to a successful finish with the reliable Herrenknecht equipment.