SP Group Construction of Transmission Cable Tunnels

SP Group Construction of Transmission Cable Tunnels



2006 – 2008








With rapid growth and urbanisation of Singapore’s economy and society, demand for power supply has increased, pushing for the need to build a more sustainable solution to the ongoing upgrading and renewal of our grid infrastructure. Planning and undertaking the responsibility to serve the ever-increasing needs of Singapore, the SG Group had carried out and completed the Construction of Transmission Cable Tunnels. With the new cable tunnels, it will allow replacement of existing underground cables to meet the increasing demand for power supply.


For this national project, MSI provided consultancy services related to bored tunnels, mined tunnels, shaft excavation and construction of associated structures. The tunnels, to be excavated to an internal diameter of 6m, run east-west across the island state for 16.5km, and north-south for 18.5km, intersecting at May Road. With a combined tunnelling length of 35km, these cable tunnels were constructed at a depth of approximately 60m where the engineering challenges were unavoidable as the team worked tediously behind the scenes to overcome them.


The challenges which accompanied the tunnelling work at such depth, were not limited to the geologies which the Cable Tunnels had to go through. The geologies included Faults, Fault Damaged Zones, Hot Springs, Blocky Rock Condition, High Rock Strength and the High Abrasiveness of the rocks. These challenges increased the difficulty levels and risks as the tunnelling works crossed the Nee Soon Fault, Springleaf MRT station, PIE expressway and Whampoa canal. In the midst of tunnelling, the team had to adapt quickly to changes in geologies as many transition zones of Bukit Timah Granite, Jurong Formation, Clayey Old Alluvium and Old Alluvium awaited within the tunnelling alignments.





Geotechnics & Tunnelling, Singapore