Completion of Singapore’s North-South Corridor (NSC) has been delayed by two years because of challenging ground conditions along the 12.3km tunnelled section.
The Land Transport Authority (LTA) says more than 90% of the foundation works for the alignment have been completed and excavation is ongoing but the ground conditions and the close proximity of existing roads, utilities and operational MRT infrastructure had slowed progress.
Some of the most technically demanding works are at Novena where the NSC passes above and below the operational North-South MRT line, with clearance down to 1m.
Fractured rock and groundwater inflows hampered progress on the northbound drive below the NSL, forcing contractors to adopt a more controlled mining method. Excavation is being completed in smaller, separately supported sections, together with additional rock removal, grouting and monitoring.
LTA says the compartmentalised excavation provides tighter control over ground movement and settlement, which is critical given the close proximity of the operational NSL tunnels.
At Thomson Road, site investigations revealed harder-than-expected rock and highly variable ground conditions. Extensive controlled rock blasting, additional rock removal and ground stabilisation works were required before excavation could proceed.
The construction methodology and earth-retaining systems have also been revised.
Ground conditions have also created delays on the line’s 8.8km viaduct section.
LTA says it will deploy additional labour and equipment where effective, optimise construction sequences and prioritise critical activities to make up time where feasible but ultimately the two-year delay means the viaduct will now open in phases from 2029, instead of 2027, and the tunnel section is expected to open in phases from 2031.
The 21.5km NSC will be a multi-modal transport corridor connecting the northern region to the city centre. It is designed to support new growth in the north and relieve congestion on the Central Expressway and major arterial roads.
