Robbins Breakthrough in SingaporeOn 26th January, 2005 Robbins 4.3 m-diameter double shield TBM 1413-301 broke through in Singapore. This completed the excavation of the second and final tunnel on the Senoko Power Station to Gambas Avenue Cable Tunnel Project. The construction contract was awarded to the joint venture consisting of Obayashi of Japan and McConnell Dowell of Australia. The project owner is Powergrid Ltd of Singapore.At its onset, the project was anticipated to be challenging with extremely hard granite and TBM excavation of 90 degree turns with 100 m radii. In fact, the challenges faced were more extreme. During the first 200 m of boring, theTBM faced high water inflows and flowing ground. Many months of surface and underground grouting were required to solidify the material. During the grouting process, the JV was advised that access to the Senoko Shaft (the reception shaft) had been denied. The client had to find a new location for the shaft.Partway through the excavation of the first tunnel, the Robbins double shield TBM was modified to improve performance in poor ground. After modifications, the TBM bored with better production rates and the rock improved. Upon completion of the first tunnel, the TBM was parked for several months awaiting the new shaft to be sunk at Senoko. The second tunnel was lowered by 10 m to improve ground conditions, and the 1.8 km drive was completed in less than five months. The Obayashi-McConnell Dowell JV has successfully completed the most difficult task on an extremely challenging project. Visit www.robbinstbm.com 06/05.