Cross Island Line Construction: CRL - A snapshot in July 2025

Overview of CRL1 works under contracts CR106 - CR117 as at July 2025.
Top (L - R): CR106 - Loyang, CR4 - Pasir Ris East, CR5/CP1 - Pasir Ris, CR6 - Tampines North
Middle (L - R): CR110 – Large diameter tunnel, CR7 - Defu, CR8 - Hougang, CR9 - Serangoon North
Bottom (L - R): CR10 – Tavistock, CR11 – Ang Mo Kio, CR12 - Teck Ghee, CR13 - Bright Hill

There's a fair bit to update in this snapshot of the Cross Island Line (CRL) for July 2025. This update will mainly focus on progress along phase 1 of the line, the section with the most progress thus far due to the section's earlier announcement, contract award and commencement in general. Nonetheless, tunneling is also underway across all announced phases thus far, so we will touch a little on the progress made on that front thus far. All this & more after the jump.

Phase 1
Most of the stations along phase 1 are still busy with the construction of the earth retaining & stablising systems (ERSS), which take the form of diaphragm walls or bored piles. A handful have commenced excavation works - such as Tampines North, Defu and Hougang. Tunneling works along the phase were in full swing, with 5 tunnel sections completed thus far, out of 29 - approximately 17% of the tunnel sections. Considering that tunneling works only commenced in 2024, this is good progress. Tunnel boring works are expected to complete by 2027.

Tunneling chart for CRL's phase 1.

CR3 - Loyang (Contract CR106)
In a nutshell: Tunneling works for both bounds was in progress. Interestingly, the launch shaft for this contract is located next to the site for the adjacent contract CR107, with the shaft being constructed by that contractor as well. It was then handed over to the contractor for CR106, which has since commenced tunneling works. A watchman station, denoted by a big multi-colour umbrella, was present along Pasir Ris Drive 2. These mobile stations are deployed to allow the contractor to monitor any settlement incidents along the Tunnel Boring Machine (TBM)'s path, allowing quick responses & remedial actions. You might be familiar with the sinkhole incident along Tanjong Katong Road South, which occurred next to a Public Utilities Board (PUB) sewer construction site. The watchman station functions for early identification, reaction to and prevention of similar incidents along the TBM's path.

31 July 2025

Where is the TBM?
Based on observations, both TBMs had commenced tunneling works, although only 1 watchman station could be seen. One of the TBMs, as of 31 July 2025, was located underneath Pasir Ris Drive 2.

Tunneling chart for contract CR106.

July 2025 - Approximated location of contract CR106 TBM.
Base map from URA Space.

31 July 2025

CR4 - Pasir Ris East (Contract CR107)
In a nutshell: With tunnel boring taking place at one end of the site (at the launch shaft, since handed over to contract CR106), diaphragm and cross wall construction works continued within the station box site. King posts were also observed on site, which would be added into the ground to provide stability to the station box once excavation works commence. These are long steel poles which are sunk into the ground and embedded in piles, serving as temporary columns to hold up the roof, concourse and platform slabs as they are constructed.

31 July 2025

CR5 | CP1 - Pasir Ris (Contract CR108)
In a nutshell: Works at the Pasir Ris station site were spread out over a rather long work site, stretching from Sungei Tampines all the way to Coco Palms condominium. At the eastern end next to Sungei Tampines, work was ongoing within the excavated launch shaft to prepare for eventual TBM assembly within. Since the road was swung out in June, access to the launch shaft has become a lot easier. Further west, works were in progress for the diaphragm walls of the cut & cover tunnel section. This would allow tracks from the Punggol extension to rise upwards to meet the main line tunnels of the CRL Phase 1, providing trains on the Punggol extension with access to the Changi East depot.

At the station box area, similar works were underway as well, with hydrofraise machines on site to dig the trenches in which rebar cages are lowered to construct the diaphragm walls. Part of the section that would allow transfers to the existing East-West Line (EWL) station had commenced excavation works. Tubular struts were being used along this section. At the western-most end, traffic decking was being installed over the crossover box located west of the station.

31 July 2025

CR6 - Tampines North (Contract CR109)
In a nutshell: The gantry cranes have been completely disassembled from the northern launch shaft and re-assembled at the southern launch shaft. This indicates conclusively that tunneling works to Pasir Ris station have concluded. A watchman post was seen along Tampines Avenue 11 where the TBM boring the westbound tunnel has commenced its drive towards Facility Building 3. At the station box, excavation works continued with strutting advancing towards the north. The entire station box has nearly been completely marked out by now.

24 July 2025

Where are the TBMs?
The TBM boring the westbound tunnels towards Facility Building 3 has been launched, and as of 24 July 2025, was located beneath the junction of Tampines Avenues 6 and 11.

Tunneling chart for contract CR109.

July 2025 - Approximated location of contract CR109 TBM.
Base map from URA Space.

24 July 2025

CR7 - Defu (Contract CR111)
In a nutshell: With both TBMs launched, progress is being made rather quickly. TBM Daphne, boring the westbound tunnel, has completed more than half of her drive with the TBM being located in the vicinity of Hougang CC. TBM Hera, boring the eastbound tunnel, was in the vicinity of Hougang Rivercourt BTO development due to a much later launch. Excavation work was underway at the station box, with the first level of struts installed.

24 July 2025

Where are the TBMs?
One TBM, Daphne, was approximately halfway through her drive towards Hougang station. Daphne was located beneath the carpark behind Hougang Community Centre. TBM Hera was launched later on, and was still located along Tampines Road in front of the Hougang Rivercourt BTO precinct.

Tunneling chart for contract CR111.

July 2025 - Approximated location of contract CR111 TBMs.
Base map from URA Space.

24 July 2025

CR8 - Hougang (Contract CR112)
In a nutshell: Diaphragm wall construction appears to be tapering down with the removal of the hydrofraise machines from the main station box site. Preparation works for an upcoming road diversion of Hougang Central (Major) some time in Q4 were also in progress. Within the existing North East Line (NEL) station, the lift connecting the concourse and platform levels was shut down for modification works. A temporary platform lift began operations to replace the permanent lift as it undergoes upgrading & modification works. This arrangement will be in place for 18 months.

31 July 2025

24 July 2025

22 July 2025

Where are the TBMs?
TBM Artemis was the first to be launched, and as of 24 July 2025, was located along Hougang Avenue 8. TBM Valkyrie was the second to be launched and was located further behind.

Tunneling chart for contract CR112.

July 2025 - Approximated location of contract CR112 TBM.
Base map from URA Space.

24 July 2025

CR9 - Serangoon North (Contract CR113)
In a nutshell: A road diversion was carried out this month to swing Ang Mo Kio Avenue 3 further north, allowing works on the southern half of the station to begin. With the process only recently completed, works to remove the asphalt laid for the previous stage of road diversion had yet to be removed.

24 July 2025

CR10 - Tavistock (Contract CR115)
In a nutshell: The fourth set of TBM shield was delivered to the intermediate launch shaft site, ready for assembly to allow TBM1 to complete its second drive towards Ang Mo Kio station. Several back up gantries were noted on site with remnants of excavated soil along the top portion. This would likely indicate that the first drive has since been completed and the TBM parts were being removed for reassembly within the new shield, which was confirmed at the road show held for the contract on 2 August 2025.

24 July 2025

Where are the TBMs?

Three TBMs will be used for 4 drives under this contract. The first TBM, referred to as TBM1, had completed its first drive towards Ang Mo Kio station. The back up gantries had since been retrieved from the tunnel and brought back to the surface at the launch shaft. A new shield was being prepared before being lowered for the second drive along the westbound tunnel. TBMs 2 and 3 were on their way towards Serangoon North and Tavistock stations respectively.

Tunneling chart for contract CR115.

July 2025 - Approximate location of contract CR115 eastbound TBMs.
Base map from URA Space.

CR11 - Ang Mo Kio (Contract CR116)
In a nutshell: TBM Fatimah had completed her first drive from the contract's intermediate launch shaft to Teck Ghee station. With this, a second TBM shield was waiting on site for assembly for the subsequent drive. No back up gantries were seen at the site of the intermediate launch shaft yet, likely indicating that retrieval had not yet been achieved.

24 July 2025

17 July 2025

Where is the TBM?

The contract uses a single TBM, named Fatimah, to construct 4 drives. The first drive towards Teck Ghee station along the eastbound tunnel has since been completed. At 200m long, the drive was a rather short one, approximately 5 times the length of the TBM which was designed on an atypically compact 45m length. A new shield was awaiting on site ahead of tunneling works commencing for the second drive.

Tunneling chart for contract CR116.

CR12 – Teck Ghee (Contract N109A)
In a nutshell: Excavation has commenced along the challenging site where the North-South Expressway is being built above the station box. Parts of the permanent structure, such as the roof slab of the subways near Exit 4 have been cast and are visible.

24 July 2025

CR13 – Bright Hill (Contract CR117)
In a nutshell: Works at the station were focused on the construction of the ERSS as bored piling works continued around the station perimeter. Tunneling works were in full swing for the tunnels connecting to Teck Ghee station.

24 July 2025

Where is the TBM?
The watchman station was seen outside the perimeter fence of Innova Junior College (JC) last month, but has since disappeared. As such, the TBM is likely to be passing through the JC campus.

Tunneling chart for contract CR117.

Punggol Extension
Tunneling works along the Punggol Extension were underway for contract P103. In this contract, the large diameter TBM would bore a single tunnel from the cripple siding site in front of Pasir Ris camp and end its first drive at Punggol station. A second drive would connect the line from the cripple siding site to the Elias station. Under contract P102, a single TBM would be used to bore a set of twin tunnels connecting to Pasir Ris station in 2 drives. Tunneling under contract P102 had not commenced yet, although launch shaft construction was well underway.

Tunneling chart for CRL's Punggol Extension.

Phase 2
This section of the line reached a milestone in early July with the groundbreaking ceremony being held at Clementi station. The same day, the opening ceremony was also held for the Project Information Centre (PIC) for phase 2 of the line. You can read more details about the 3 PICs for the various sections of the line here:

The Land Transport Authority (LTA) kindly invited us to attend the ceremony where we got the chance to understand more about phase 2's engineering challenges. For instance, the tunnel alignment between Turf City & King Albert Park stations passes underneath a large neighbourhood of landed properties. It was not possible for soil investigations to be conducted every few metres here, posing a challenge for engineers to understand the ground composition in the area. It is imperative for the engineers to understand what types of rocks make up the ground to allow them to plan for stoppages of the tunnel boring machines (TBMs) in safe locations. Stoppages are needed to replace parts of the scrapers and cutters on the cutterhead that will be worn down after prolonged use.

To overcome this limitation, other techniques for understanding the ground were used instead. One such method was the use of ground penetrating radar to allow engineers to understand the soil composition from alternate methods. Such alternatives, combined with historical records and other regular soil investigation methods allowed engineers to overcome the hurdles presented.

7 July 2025

Thus far, only 1 contract has commenced tunneling works along phase 2 - contract CR202. Tunneling under this contract involves the construction of a 5.7km long tunnel up to 70m deep below the Central Catchment Nature Reserve to connect Turf City station with Bright Hill station along phase 1.

Tunneling chart for CRL's phase 2.

A similar but consolidated (a.k.a. simplified) post will be available on Instagram & Facebook on 16 August 2025.

Cross Island Line Construction

Saturday, August 9, 2025

CRL - A snapshot in July 2025

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