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 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, he 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.
LTA, in response to queries, said soil investigation boreholes sample ground conditions only at set locations and intervals, and this type of ground anchor is difficult to detect unless a borehole intersects at a location where an anchor is present.
“At this stage, there is no indication of similar undocumented anchors elsewhere along the tunnel alignment of Cross Island Line. The issue is specific to this location,” it 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.
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