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| CRL1 tunnel chart as of end-2025, to the team's best knowledge. |
Tunneling works along the Cross Island Line (CRL)'s phase 1 have been progressing well, thanks to the favourable soil conditions in the eastern side of the island. Soil here is typically composed of old alluvium, great for tunneling as seen through the quick work made of tunnels under several contracts of late.
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August 2023 - A view of the displays within the CRL1 Project Information Centre. The display
on the left shows the Soil Profile along the CRL1. |
Old Alluvium is a dense and strong material, capable of supporting the surroundings while tunneling work is being carried out. While strong, it is also easier to tunnel through than Bukit Timah Granite, an extremely hard rock that dominates the soil profile of Western Singapore. The transition from Old Alluvium to Bukit Timah Granite takes place in the vicinity of Ang Mo Kio and Teck Ghee.
With the favourable Old Alluvium in Eastern Singapore, here are some updates on tunneling work across CRL1.
- Contract CR106 - The second tunnel boring machine (TBM) has passed under housing blocks and is in the vicinity of Loyang Avenue.
- Contract CR109 - The westbound TBM has completed its second & final drive. Eastbound TBM was boring underneath Tampines Road in the vicinity of Tampines Dormitory.
- Contract CR111 - Both TBMs have completed their drives towards Hougang station.
- Contract CR112 - According to the Land Transport Authority (LTA), both TBMs have completed their drives toward Serangoon North station.
- Contract CR116 - As of end-November, the TBM's second drive was 63% completed.
Contract CR106 - Loyang station and tunnels connecting to Pasir Ris East station
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| Tunneling details for contract CR106, from Pasir Ris East to Loyang. |
Work to construct tunnels connecting Pasir Ris East station with Loyang station have been underway since the middle of the year. Two TBMs were being used to construct the twin bored tunnels, with the watchman station for the second machine seen along Loyang Avenue. The watchman station for the leading TBM was previously seen at the junction of Loyang Avenue with Pasir Ris Drive 3 and New Loyang Link.
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26 October 2025 - Watchman station for the lead TBM at the junction of Loyang Avenue with
Pasir Ris Drive 3 and New Loyang Link. |
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| 26 October 2025 - A close up view of the watchman station. |
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| 26 October 2025 - Watchman station for the trailing TBM next to block 268. |
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| 26 October 2025 - Another view of the trailing TBM's watchman station. |
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| 14 December 2025 - Trailing TBM's watchman station along Loyang Avenue. |
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| 14 December 2025 - Another view of the trailing TBM's watchman station. |
Contract CR109 - Tampines North station and tunnels connecting to Pasir Ris station & Facility Building 3
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| Tunneling details for contract CR109, from Tampines North to Pasir Ris & Facility building 3. |
Under this contract, 2 TBMs were to be used on 2 drives each to construct a total of 4 tunnels connecting to neighbouring contracts. The machines were first launched in mid-2024 for their first drives towards Pasir Ris station, potentially to allow work there to complete ahead of CRL Punggol Extension (CPE) contract P102's tunneling work towards Pasir Ris station too. These tunnels were completed by around Q1 2025. Towards the middle of Q2 2025, the machines were being assembled for their second drives, with the westbound machine launched by July 2025.
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14 June 2024 - The launch of contract CR109's TBMs for their first drives.
Source: Baey Yam Keng |
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29 May 2025 - New shields for the re-assembly of machine for its second drive. Back up gantries
can be seen in the background as well. |
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June 2026 - A view of the TBM with segments for its initial drive visible.
Source: LinkedIn |
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June 2026 - A view of the TBM from inside the southern launch shaft.
Source: LinkedIn |
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| 24 July 2025 - Watchman station for the westbound TBM. |
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| 24 July 2025 - Portable & makeshift sign to indicate the TBM's location. |
The eastbound TBM soon followed suit, with the watchman station becoming visible along Tampines Avenue 11. By November, the watchman station for the westbound TBM was seen just outside the boundary of contract CR110's worksite. Subsequently, the watchman station was no longer seen, likely indicating that tunneling works had been completed for the bound. Around this time, the watchman station for the eastbound tunnel had advanced along to Tampines Road.
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| 19 October 2025 - Watchman station along Tampines Avenue 11. |
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19 October 2025 - Portable & makeshift sign, this time indicating
TBM-2B (Eastbound) instead. |
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| 6 December 2025 - Watchman station visible just ahead of Tampines Dormitory bus stop. |
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| 6 December 2025 - A view of the watchman station along Tampines Road. |
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| 6 December 2025 - Portable & makeshift sign seen. |
The confirmation of the westbound TBM's breakthrough at the Facility Building 3 (FB3)'s site came through this month, with several celebrative images showing workers standing within the tunnel to mark the milestone moment.
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December 2025 - Workers carrying a banner showing that tunneling works for the westbound
tunnel were completed.
Source: Facebook |
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December 2025 - Another view of the TBM at the end of its 2 drives.
Source: LinkedIn |
It can be inferred that tunneling work for the eastbound tunnel is still likely to be underway, given that the TBM was launched later than the westbound machine. Nonetheless, breakthrough is probably about to happen very shortly. The completion of tunneling works for this tunnel will mean that contract CR109 will have completed all tunnel boring works.
Contract CR111 - Defu station and tunnels towards Hougang station
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| Tunneling details for contract CR111, from Defu to Hougang. |
Contract CR111 involves the construction of 2 bored tunnels with 2 TBMs, connecting Defu station to Hougang station. TBM Daphne, boring the westbound tunnels for the contract, was the first TBM to be launched for the contract around Q1/Q2 2025. With TBM Daphne on its way towards Hougang, there came news thereafter that the next TBM would be named Hera. TBM Hera would bore the eastbound tunnels of the contract.
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March 2025 - A view of TBM Daphne in the contract's launch shaft.
Source: LinkedIn |
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| 19 May 2025 - Watchman station visible next to Hougang Rivercourt. |
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May 2025 - The tunnel of the left was being constructed by TBM Daphne. To the right, the
contract's second TBM could be seen - TBM Hera.
Source: LinkedIn |
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July 2025 - A view of TBM Hera with the initial drive commenced.
Source: LinkedIn |
In October, we noticed parts of the TBM had been dismantled and lifted out of the tunnels at the Defu station site. This likely meant that tunneling works for the first TBM had been completed. The disappearance of the watchman station at Hougang station also further affirmed that TBM Daphne had completed its drive. At the same time, the watchman station for TBM Hera could still be seen along Upper Serangoon Road.
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26 October 2025 - The ring segment erector and corkscrew conveyor visible within the station
site. |
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| 26 October 2025 - Watchman station along Upper Serangoon Road. |
The LTA later announced in early-December that tunneling works for contracts CR111 & CR112 had been completed.
Contract CR112 - Hougang station and tunnels towards Serangoon North
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| Tunneling details for contract CR112, from Hougang to Serangoon North. |
The TBMs for contract CR112 were launched between Q1 and Q2 2025, with TBM Valkyrie tackling the westbound tunnel and TBM Artemis tackling the eastbound tunnel. Watchmen stations could be seen at various points along the tunnel's alignments.
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| 21 June 2025 - Watchman station next to blocks 507 & 501. |
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| 24 July 2025 - Watchman station in front of block 608 along Hougang Avenue 8. |
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29 September 2025 - A portable & makeshift sign denoting the location of the TBM along
Hougang Avenue 2. |
In early-December, in similar fashion to that seen at contract CR111, we noticed parts of the TBM re-emerging at the station site. The emergence of these TBM parts heralded the completion of tunneling works for at least 1 tunnel. According to LTA, all tunneling works have been completed. Subsequently, further TBM back up gantries were seen on site.
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6 December 2025 - A view of the launch shaft with the ring segment erector and corkscrew
conveyor visible. |
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| 6 December 2025 - A close up view of the ring segment erector and corkscrew conveyor. |
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| 6 December 2025 - TBM gantries not seen at the the section of site used for tunneling works. |
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| 24 December 2025 - TBM back up gantries seen on site. |
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| 24 December 2025 - A close up view of the TBM back up gantries seen on site. |
CR116 - Ang Mo Kio station & tunnels to Teck Ghee
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Tunneling details for contract CR116, from an intermediate launch shaft to Teck Ghee & Ang Mo
Kio stations. |
As of November 2025, the second drive towards Teck Ghee station was well underway. This drive saw TBM Fatimah boring the westbound track, with progress at 63%. Unlike sections further east, the soil profile here was slight different with harder and more abrasive Bukit Timah granite being encountered. Tunneling for the eastbound tunnel, a stretch of around 200m from the intermediate launch shaft, took 37 working days. This excluded 5 scheduled stops for maintenance of the TBM's cutterhead and change out of tools given the nature of the ground profile.
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28 November 2025 - A view of the westbound tunnel from the intermediate launch shaft towards
Teck Ghee station. Completion of the tunnel was at approximately 63%.
Source: LinkedIn |
Good progress has been made over the year for tunneling works along CRL1. With the completion of at least 5 more tunnels in the past quarter, tunneling work is approximately 1/3 completed for phase 1. We look forward to the continued progress that 2026 is sure to bring, with the bulk of tunneling work to be completed next year.
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