Chennai Metro begins tunnelling work between Nungambakkam and Sterling Road
- Tunnelling work has commenced on the 1.2 km stretch between Nungambakkam and Sterling Road.
- The tunnel is part of Chennai Metro's Phase 2 expansion, covering 118.9 km.
- The route will pass under key roads and buildings, with construction expected to take over a year.
Tunnel work begins on key Metro stretch
Chennai Metro Rail has started tunnelling work on a critical 1.2 km stretch connecting Nungambakkam and Sterling Road. The tunnel forms part of the city's Phase 2 expansion, which aims to add 118.9 km of new lines across the metropolitan area.
Officials said the work began this week with the deployment of a tunnel boring machine (TBM) at the launch shaft near Nungambakkam. The machine will dig at an average depth of 15 to 20 metres below ground level.
Route and challenges
The tunnel will run under busy roads and commercial areas. The alignment passes close to several high-rise buildings and heritage structures. Engineers have conducted soil surveys and structural assessments to minimise risks.
Metro officials said the boring process will take about 14 months. The TBM will move at roughly 10 metres per day, depending on ground conditions. The stretch is part of the 26-km corridor connecting Madhavaram and Sholinganallur.
Impact on traffic and residents
Traffic on stretches of the route may be affected during construction. Metro authorities have promised to maintain at least two lanes of traffic open at all times. Pedestrian diversions and signage will be put up near the work sites.
Residents in the area have been informed about potential noise and vibration. The Chennai Metro Rail Corporation has set up a helpline for complaints. Officials said they will monitor air quality and dust levels around the tunnel portal.
Phase 2 progress so far
Phase 2 of Chennai Metro is being executed in three corridors. Corridor 3 runs from Madhavaram to Sholinganallur via the city centre. Corridor 4 connects Lighthouse to Poonamallee Bypass. Corridor 5 links Madhavaram to Sholinganallur along the Inner Ring Road.
Work on several other stretches is already underway. The full Phase 2 network is expected to be operational by 2027. The project is funded jointly by the central and state governments, with some assistance from the Japan International Cooperation Agency.
What happens next
The TBM will now advance towards Sterling Road. Once it reaches the retrieval shaft, the tunnel lining will be completed. Stations at Nungambakkam and Sterling Road will be built simultaneously. Officials said they will update the public on milestones as the tunnelling progresses.