LTA: North-South Corridor Singapore engineers face most challenging construction phase as rocks and viaduct slow work progress

The North-South Corridor (NSC) project in Singapore has entered its most challenging construction phase, with engineers encountering difficult ground conditions that have slowed progress. The 20km project, spanning from Singapore's northern towns towards the city, includes an 8.8km elevated viaduct and a 12.3km underground tunnel section. Construction began in 2018 and is expected to be completed in phases, with the viaduct opening in 2027.

One of the most difficult sections of the project is the Novena area, where a tunnel section passes within about 1m of the existing North-South Line. This proximity has required extra tunneling safety measures, such as smaller excavation sections and additional ground support. Engineers have encountered fractured rock and groundwater while digging beneath existing MRT tunnels, necessitating specialized techniques like controlled blasting and extra grouting.

The 8.8km viaduct, which is the longest in Singapore, is being built at a height of 19m and will be constructed using over 6,000 precast pieces. Much of the work on the viaduct takes place at night, requiring four to five-hour windows to avoid disrupting live roads, major junctions, and existing transport infrastructure. Foundation work at locations such as Gambas Avenue and Woodlands Avenue 8 has taken longer than expected due to the presence of utilities and challenging ground conditions.

Despite these obstacles, over 90% of the foundation work is now complete, and attention is shifting towards the installation of columns, crossheads, and launching viaduct sections above roads and MRT tracks. The LTA has implemented additional safety measures to protect workers and nearby infrastructure, which should gradually reduce the level of disruption for residents and businesses in the affected areas.