CHENNAI (Metro Rail News): Chennai Metro Rail Limited (CMRL) has recorded 3 TBM breakthroughs in three consecutive days, adding momentum to the underground works on Chennai Metro Phase II. The latest came on October 1, when downline TBM Adyar broke through at RK Salai Station on Corridor 3.
The three breakthroughs were recorded across two underground corridors between September 29 and October 1.
Chennai Metro records 3 breakthroughs in 72 hours
The sequence began with the Kaveri TBM on September 29, followed by Maruthan on September 30 and Adyar on October 1.
- 29 September: Corridor 3 downline TBM Kaveri broke through at Kilpauk Medical College Station.
- 30 September 30: Corridor 5 downline TBM Maruthan broke through at Villivakkam Station.
- 1 October: Corridor 3 downline TBM Adyar broke through at RK Salai Station.
The latest breakthrough is also the 10th TBM breakthrough under the TU02 contract.
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Adyar completes 915-metre drive
TBM Adyar was deployed for tunnelling between Royapettah and RK Salai stations along Chennai Metro Corridor 3. The downline tunnel is 915 metres long. The drive began on December 29, 2025, and was completed on October 1, 2026, taking 277 days.
The tunnel forms part of the 12-km underground section between Kellys and Taramani, where L&T is executing the tunnelling works with eight TBMs. The corresponding upline drive was completed earlier by TBM Bhavani, which broke through at RK Salai on October 13, 2025.
TBM passed below busy urban stretch
The Royapettah–RK Salai drive involved tunnelling below or close to several existing structures along Royapettah High Road. The machine negotiated sections near:
- Peters Bridge
- EPFO building
- Andhra School
- Several commercial shop lots
The tunnel was constructed at an overburden of about 9 to 13 metres through silty sand. The tunnelling team carried out 11 cutterhead interventions during the drive.
Despite the relatively shallow alignment and the presence of existing structures, CMRL said the work was completed without major ground settlement or reported damage to surrounding infrastructure.
Chennai Metro Corridor 3 gains another tunnelling milestone
The latest breakthrough adds to the progress on Corridor 3, one of the underground sections of Chennai Metro Phase II. The repeated breakthroughs in a short period also reflect the pace of tunnelling activity now underway across the Phase II network. However, TBM breakthroughs mark the completion of individual tunnel drives and are followed by track, systems, station and other works before a corridor can enter testing and commissioning.
The three breakthroughs in three days give Chennai Metro Phase II a visible tunnelling push, with Corridor 3 recording two of the three milestones. The focus now shifts to completing the remaining tunnel drives and moving the finished sections towards the next stages of construction, systems installation and commissioning.
Also Read: Chennai Metro Phase-2 Advances as L&T’s ‘TBM Kaveri’ Breaks Through at Kilpauk
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