LTA Reports Technical Challenges and Ground Condition Obstacles for North-South Corridor

Construction of the North-South Corridor (NSC) is entering its most technically demanding phase as the Land Transport Authority (LTA) manages challenging ground conditions and complex engineering requirements. The project, which spans more than 20km and includes an 8.8km elevated viaduct and a 12.3km underground tunnel section, has encountered unexpected obstacles at several locations. In Novena, tunnelling crews found hard rocks and water seepage instead of the anticipated softer clay, complicating work on a tunnel that passes as close as one metre beneath the operational North-South MRT line. In the Thomson area, engineers encountered large boulders and a hard rock layer closer to the surface than expected.

To safeguard existing infrastructure, the LTA has adjusted its construction methods. In Novena, workers shifted to a compartmentalised excavation strategy, digging the tunnel in small sections to prevent ground movement. In the north, foundation works at Gambas Avenue and Woodlands Avenue 8 were slowed by utility diversions and adverse ground conditions. The LTA noted that because viaduct works are sequential, these foundation delays have impacted subsequent activities. The viaduct, which will be Singapore's longest, requires the installation of over 6,000 precast elements, often during narrow night windows to minimize traffic disruption.

While the LTA previously stated that the viaduct section is expected to open from 2027, other reports indicate the project was delayed by Covid-19 to 2029. When asked if current engineering challenges would further delay completion, an LTA spokesperson stated that the authority is monitoring progress and will provide a timeline update in due course.