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Workers installing one of the final steel plates using a robotic arm during works in a tunnel at the Dakota MRT station on Feb 9.

ST PHOTO: KUA CHEE SIONG

Vanessa Paige Chelvan

SummaryCircle Line tunnel reinforcement between Mountbatten, Dakota and Paya Lebar is almost 50% complete. Work on the second tunnel starts end-February, finishing by April 19.Tunnels require reinforcement due to soft clay and defects to prevent future disruptions. Robotic arms are innovatively used to install steel plates, improving safety and productivity.The three-month disruption affects 480,000 daily commuters with longer train intervals.AI generated

Published Feb 10, 2026, 12:00 PM

Updated Feb 10, 2026, 01:06 PM

SINGAPORE – Nearly half of the works

to reinforce the underground tunnels

The completed stretch is in the direction of HarbourFront station.

Works will move to the second tunnel – which runs towards Marina Bay and Dhoby Ghaut – by the end of February, said Mr Saiful Rasno, director of infrastructure enhancement at the Land Transport Authority (LTA), on Feb 9.

He added that the works were on track to end by April 19.

There will be no further impact on train services or intervals beyond the current arrangements when works move to the second tunnel, and commuters can follow signage to board shuttle trains from the opposite platform, LTA said.

During the three-month planned disruption, trains are still running across the line, albeit at longer intervals.

LTA announced on Dec 10 that tunnel-strengthening works would be carried out

The tunnels connecting the stations are being closed one at a time to allow the installation of steel rings. The affected 450m stretch also includes a portion of the tunnels between Stadium and Mountbatten stations.

The stretch of tunnels was built in soft marine clay, making it more prone to deformation. Minor defects such as water leaks have already surfaced. Steel rings are being added to reinforce the circumference of the tunnels.

Although there is no immediate safety risk, failing to address these defects could lead to severe service disruptions, LTA has said.

During a visit to the tunnels between Dakota and Paya Lebar stations on Feb 9, The Straits Times witnessed the installation of the final steel ring, one of 152 rings along the stretch.

Each ring is made up of six steel plates fabricated in China to specific measurements.

More than 300 steel rings are expected to be installed by the time the works are completed.

Workers demonstrating how a robotic arm is used to install the steel plates on the tunnel wall.

ST PHOTO: KUA CHEE SIONG

Behind the scenes, engineers are relying on specialised machinery to carry out the tunnel works efficiently and safely in a round-the-clock operation.

During the Feb 9 demonstration, engineers showed how a robotic arm is used to install the steel plates with precision. This is the first time robotic arms are being used in such tunnel works, Mr Saiful said.

“We are able to achieve good progress using the robotic arm and getting good productivity,” he said.

Each plate weighs about 800kg. The robotic arm lifts the plate to the tunnel wall and holds it in position while engineers drill five mechanical bolts to temporarily secure it.

The robotic arm lifts the plate to the tunnel wall and holds it in position while engineers work on securing it.

ST PHOTO: KUA CHEE SIONG

The process is repeated along the tunnel using two robotic arms, each operated by a specialist from China. In total, five operators are involved, alongside more than 300 engineers and contractors who have been working round the clock in shifts since work began.

With the steel plates now installed in the first tunnel, crews are carrying out finishing works. These include permanently securing the plates to the tunnel wall using chemical bolts containing epoxy – an adhesive used to bond or seal materials – as well as welding and grouting works, Mr Saiful said. Grouting involves filling voids or cracks with a dense fluid mixture.

Each steel plate requires 120 bolts, and installing one steel ring with six plates takes about four hours.

LTA engineers said the use of robotic arms has significantly reduced the labour needed in the confined tunnel space. Without the machinery, five or six workers would be required to lift each plate manually – a difficult and potentially unsafe task given the tight working space.

Even with the robotic arms, about 300 workers are deployed in the tunnels. Without them, labour needs would be many times higher, LTA added.

The works are further complicated by the presence of live utilities and services running along the tunnel walls, including cables that power signalling and electrical systems. These had to be carefully shifted forward to allow the steel plates to be installed behind them.

Electric and signalling cables had to be carefully shifted for the steel plates to be installed in the tunnels.

ST PHOTO: KUA CHEE SIONG

To prevent damage, the live cables are wrapped in cloth during welding works, shielded with PVC pipes and protected using fire blankets, as they are highly sensitive.

Once the finishing works are completed, LTA will conduct comprehensive testing of the tunnel. The tests ensure that the strengthened tunnel is robust and reliable for passenger service, it said.

Workers seen during a media tour of one of the tunnels at the Dakota MRT station.

ST PHOTO: KUA CHEE SIONG

About 500 additional employees have been deployed at affected stations and key interchanges to assist commuters and direct them to alternative travel routes during the service adjustments.

At three months, this is one of the longest planned MRT service disruptions so far.

During this period, shuttle trains run on a single platform at 10-minute intervals connecting Mountbatten, Dakota and Paya Lebar stations. This is slower than the usual three-minute frequency.

Passengers need to switch to another train at Mountbatten or Paya Lebar to continue their journey on the CCL.

There are slightly longer waits between trains along the entire length of the CCL during this period.

The 20-station stretch between HarbourFront and Paya Lebar sees peak-hour intervals rise from two to three minutes. Train intervals between Mountbatten and the Dhoby Ghaut and Marina Bay stations also increase from six to 10 minutes.

Several shuttle bus routes are operating during weekday peak hours to provide an alternative to passengers.

An average of 480,000 passengers are affected each day.

More on this topicWhat you need to know when taking the Circle Line from January to AprilLonger waits for CCL trains from Jan 17 to April 19 due to tunnel works between three stationsVanessa Paige Chelvan is a correspondent at The Straits Times. She writes about all things transport and pens the occasional commentary.

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