On Saturday, April 14, 2018. a 6.67m diameter CREG TBM (CREC 426) broke through on Changi Bound drive of Thomson Line Contract T227 and on a high note. The EPB TBM was launched on January 27, 2018 for the 750m tunnel drive and finished its job in two and a half months, two months ahead of the schedule. That’s another exciting news following the completion of The Woodlands Bound drive by CREC 216. The machine broke through on November 29, 2017, 43 days ahead.
The geology of Contract T227 is quite a challenge for TBM excavation. It consisted of reconsolidated soil, sandy clay (mixed with peat soil), old and new alluvial soil. The soil is generally soft and unsteady for EPB to bore. The reception part of Changi Bound drive includes 359m of parallel tunnels and the minimum clear spacing in-between is 4m. TBM for the Woodlands Bound drive has to underpass a 1500mm sewer line. The minimum curve radius is 300m and the spacing between dislocation segments shall not exceed 5mm.
With the two tunnels boring, CREG field service staff were on hand to assist and support as required. During the course of each bore, CREG advised how best to maneuver through challenging ground and best operate the machine. Thanks to their efforts, the two machines did efficient performance.
The two drives are part of the construction of the Marina South station and tunnels, wich is awarded to Sinohydro Corporation Ltd. (Singapore Branch) – Sembcorp Design and Construction Pte Ltd Joint Venture by the Land Transport Authority (“LTA”).
Singapore MRT Thomson subway line is about 30 km and is expected to be put into use by the end of 2020. Once completed, it will be the major rail line connecting northern Woodlands region, the southern commercial center (CBD) and Marina Bay’s.