Introduction
Chennai Metro Rail Limited (CMRL) announced on 7 August 2026 the successful completion of tunnelling works on the first 6.3-kilometre stretch of Corridor 4 (Light House to Poonamallee) under Phase 2 of the Chennai Metro Project. The milestone was achieved with the breakthrough of the tunnel boring machine (TBM) 'Mangal' at the Alandur underground station, marking a key step toward the 2028 operational deadline for Phase 2.
Phase 2 Overview
Chennai Metro Phase 2 spans 118.9 km with three corridors and is being built at an estimated cost of ₹63,246 crore. Upon full completion, it will expand Chennai's metro network from the current 54 km (Phase 1) to over 172 km, making it one of India's largest metro networks.
- Corridor 3: Madhavaram Milk Colony to Siruseri Sipcot — 45.8 km, 48 stations
- Corridor 4: Light House to Poonamallee — 26.1 km, 28 stations (tunnelling completed on 6.3 km stretch)
- Corridor 5: Madhavaram to Sholinganallur — 47.0 km, 46 stations
Key Details of Corridor 4 Tunnelling
- Completed stretch: 6.3 km from Nandanam to Alandur
- TBM used: 'Mangal' — Earth Pressure Balance (EPB) machine
- Breakthrough station: Alandur underground station
- Stations covered: Nandanam, Saidapet, Guindy, Little Mount, and Alandur
- Depth: 18–25 metres below ground level
CMRL and TNPSC Facts
- CMRL: Chennai Metro Rail Limited — a 50:50 joint venture between the Government of India and the Government of Tamil Nadu
- CMRL Managing Director: M. A. Siddique IAS
- Phase 1 operational: 2015–2019 (Green Line and Blue Line, 54 km)
- Phase 2 approval: Union Cabinet approved in February 2021
- Phase 2 completion target: 2028 (Corridors 4 and 5 partial opening by 2027)
- Total Phase 2 stations: 122 stations (including 70 underground)
Why It Matters
Chennai Metro Phase 2 will directly impact over 60 lakh commuters in Chennai and its suburbs, significantly reducing travel time between southern IT hubs (Siruseri, Sholinganallur) and northern industrial areas (Madhavaram). Corridor 4 connects key residential areas like Poonamallee with the city centre at Light House, and provides interchange with the suburban railway network at Guindy and Beach stations.
Exam Perspective
For TNPSC aspirants: Memorise the three Phase 2 corridors with their endpoints and lengths. CMRL is a 50:50 Centre-State JV. MD of CMRL: M.A. Siddique IAS. Phase 2 total length: 118.9 km, cost: ₹63,246 crore. TBM names are sometimes asked — 'Mangal' is for Corridor 4. Alandur is an interchange station for Phase 1 and Phase 2 networks. The completion target is 2028.
Conclusion
The completion of tunnelling on Corridor 4's first stretch is a critical milestone for Chennai Metro Phase 2. The project underscores Tamil Nadu's commitment to sustainable urban transport, and upon completion in 2028, will transform intra-city connectivity, reduce congestion, and lower carbon emissions for one of India's largest metropolitan regions.