Singapore’s Land Transport Authority (LTA) has finished tunnelling works for Circle Line 6 (CCL6), resulting in nearly 55% completion for CCL6’s civil construction works.

The completion was marked with the boring of 2km-long twin tunnels stretching from Prince Edward Road station to Cantonment station.

The tunnelling works commenced in August 2019 and covered three new stations, namely Keppel, Cantonment and Prince Edward Road.

The three stretches of twin tunnels that will connect these new stations to the rest of the Circle Line were built by deploying three tunnel boring machines (TBMs).

In August 2020, the initial stretch of tunnelling works between Keppel station and HarbourFront station were over.

Last July, works to mine from Keppel station to Cantonment station were concluded.

The LTA will now get involved in the construction of structural connections between the bored tunnels and stations.

These works will be executed along with the structural works for the three new underground stations for CCL6.

In addition, structural works are moving ahead for the underground Kim Chuan Depot extension.

Following the basic civil structural works completion, track-related equipment will be deployed, along with the commencement of electrical and mechanical services.

The systems will subsequently be trialled and commissioned.

The LTA said in a statement: “The CCL6 tunnelling works had to be planned and undertaken carefully as they were carried out beneath heritage buildings and close to the foundations of many existing commercial buildings and road infrastructure in the densely built-up Central Business District.”

“At the sections which interface with the existing HarbourFront and Marina Bay stations, precautions were also taken to avoid affecting daily train operations.”

CCL6 is set to launch in 2026, closing the Circle Line loop by linking HarbourFront to Marina Bay stations.

Last month, the LTA awarded a $571.51m civil contract to Shanghai Tunnel Engineering (Singapore) Pte Ltd – LT Sambo (Singapore Branch) Joint Venture.