Singapore’s North-South Corridor (NSC) will be completed about two years later than previously planned because of challenging ground conditions and complex engineering works, the Land Transport Authority (LTA) said.
The 21.5km corridor, which will connect northern towns with the city, was previously expected to open in phases from 2027. The viaduct section from Admiralty Road West to Lentor Avenue is now expected to open in phases from 2029, while the tunnel section from Lentor Avenue to East Coast Parkway is expected to open from 2031.
The NSC comprises an 8.8km viaduct and a 12.3km tunnel. It is designed to improve connectivity between areas including Sembawang, Yishun, Ang Mo Kio, Toa Payoh, Novena and Rochor, while helping to ease congestion on the Central Expressway and major arterial roads.
LTA said more than 90 per cent of the viaduct foundation works had been completed as of August 2026. More than 90 per cent of the tunnel foundation works had also been completed, with major excavation continuing along the route.
However, construction teams have encountered several site-specific difficulties that were not fully apparent during earlier investigations.
Along Gambas Avenue and Woodlands Avenue 8, harder and fractured rock and complex utility networks required additional foundation work. Some piles also had to be driven deeper than originally planned.
The work in Novena has been particularly challenging because the NSC tunnel is being constructed in close proximity to the operational North-South MRT Line. Fractured rock and groundwater flowing beneath the existing rail tunnel forced engineers to adopt a slower excavation method involving smaller sections, continuous rock removal, grouting and additional structural support.
At its closest point, the NSC tunnel passes within about 1m of the operating MRT infrastructure, requiring extensive monitoring and careful sequencing to prevent ground movement or settlement.
In Thomson, workers encountered harder-than-expected rock formations and highly variable ground conditions. Controlled rock blasting, additional rock removal and ground stabilisation were required before excavation could continue safely.
LTA said the delays at these critical work sites had a knock-on effect because different stages of the project must be completed in sequence before subsequent structures, including columns, crossheads and viaduct segments, can be installed.
Despite the revised completion dates, LTA said motorists and commuters should see gradual improvements in travel conditions. More construction activity is expected to move underground from 2027, reducing disruption at road level.
From 2028, roads, footpaths and other public areas currently occupied by construction works will also be progressively reinstated for public use ahead of the NSC’s opening.
The authority said it would continue deploying additional manpower and equipment where effective, while adjusting construction sequences to make up time where possible.
Once completed, the NSC will also allow surface roads along the corridor to be progressively redesigned with greater priority given to walking, cycling, public transport and community spaces.
LTA said the revised timeline was necessary to ensure the remaining works could be completed safely while maintaining the operation of existing roads, utilities and MRT infrastructure.
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