Cross Island Line: Traffic to be diverted in Ang Mo Kio Ave 3 amid suspension of tunnelling works

SINGAPORE – Motorists can expect traffic delays near AMK Hub for the next 18 months while roads are realigned to remove a tangle of steel wires underground that is obstructing Cross Island Line tunnelling works.

Traffic will be rerouted during the road diversions, which will last from Nov 14, 2026, to May 2028.

The stretch of road that runs past AMK Hub mall in Ang Mo Kio Avenue 3 – next to the Ang Mo Kio Avenue 8 junction – will close partially to motor traffic. One lane will remain open for buses.

The Land Transport Authority (LTA), in a statement on Oct 16, said the closures and diversions will help its engineers take a closer look at the thick wires hindering underground tunnelling work for the Cross Island Line (CRL).

Tunnelling work for the first stage of the CRL is being paused while LTA determines the full extent of the obstruction, how the materials got there, and how all of this will impact the overall timeline of CRL works. Ground stabilisation works will also be carried out, LTA said.

The first phase of the CRL – slated to be completed in 2030 – comprises 12 stations over 29km, from Aviation Park in Changi to Bright Hill. Ang Mo Kio station is one of the four interchanges on this stretch.

LTA group director for CRL Ng Choon Yeang, in response to queries on whether the suspension of tunnelling operations will result in delays to the completion of the first phase of CRL, said the team is still assessing the impact of the obstructions.

Once traffic diversions are in place, more work will be done to investigate the obstructions before any further steps are taken, he added.

“We will share more information when it is available to us,” said Ng.

As for why the obstructions were not discovered earlier, Ng said it was an “unforeseen” development because the wires were not detected during advance soil investigation works, and not reflected in drawings made available to the team during engineering studies.

It was only when the tunnel boring machine reached that spot that the underground objects turned up, he added.

When the materials were first encountered during tunnelling works in May, LTA tried to first remove the thick wires entangled around the cutterhead before carrying on with tunnelling works.

The cutterhead is the rotating steel wheel at the front of a tunnel boring machine, which excavates soil or rock.

Between May and July, workers came across even more obstructions, and needed to intervene 100 times to stop the tunnel boring machine before removing the wires by hand.

Along the way, 22 cutters – a component of the cutterhead – were damaged and had to be replaced, and about 800kg of wires were pulled out from the machine.

Investigations later found that the wires were part of ground anchors – steel structures drilled into the ground – to temporarily support retaining walls or structures, and prevent them from shifting during construction.

LTA said running into ground anchors during tunnelling works could damage the tunnel boring machine’s cutter tools, disrupt tunnelling and pose safety risks to underground works and the roads above.

That is why tunnelling works came to a stop before ground improvement works – to strengthen and stabilise the ground where the tunnel is – began.

Workers will then start removing the obstructions from the machine, before resuming tunnelling works in a safe and controlled manner, said LTA.

To enable these efforts, the 180m stretch of road at AMK Hub in Ang Mo Kio Avenue 3 will be reconfigured for about 1½ years, starting from Nov 14.

Changes include converting the three-lane east-bound carriageway – for motorists heading towards Ang Mo Kio Avenue 8 – into one bus-only lane.

The three-lane west-bound carriageway – for those travelling towards Ang Mo Kio Central 1 – will become a two-lane road.

The pick-up and drop-off point at AMK Hub will also have its traffic direction reversed, with exiting vehicles needing to stop at a new traffic light before they turn right towards Ang Mo Kio Central 1.

Vehicles leaving the AMK Hub carpark also have to turn right towards 51@AMK mall when the new traffic arrangement is in place.

A new pedestrian crossing, complete with traffic lights, will be set up near the exit of the AMK Hub carpark.

Pedestrians can still cross the road using the existing overhead bridge, although they will only be able to access AMK Hub through the second level – and not the ground floor – during the mall’s operating hours.

LTA said motorists can expect longer lines to enter AMK Hub during peak hours, with an added travel time of about 10 to 15 minutes.

Ng said: “Safety remains our top priority. We understand the temporary traffic changes will cause some inconvenience to residents, motorists, and businesses in the area.

“These changes are, however, necessary to give our teams safe access and space to carry out the investigations, assessments, and recovery works.”

LTA said the area will remain safe for the public. It added that ground conditions around the mall will be monitored closely throughout the works.

In response to queries, a spokeswoman from Link Asset Management, which manages AMK Hub, said the mall remains open and continues to operate as usual during works at the site.

She said: “Visitors can continue to access the mall, shop and dine.

“To facilitate traffic movement, the exit route has been adjusted with clear directional signage in place to guide motorists and ensure a smooth journey to and from the mall.”