Preparatory work on the underground stretch of Metro’s phase II project has begun in areas like Madhavaram, Purasawalkam and Greenway’s Road.
In the first week of November, full-fledged work, including excavation and building of diaphragm wall, will begin in eight locations across the city. The project will span 118.9 km and will be carried out at an estimated cost of ₹61,843 crore, comprising of three corridors — Madhavaram to Shollinganallur, Madhavaram to SIPCOT and Light House to Poonamallee — with many stretches running underground.
Before constructing a tunnel, Chennai Metro Rail Limited (CMRL) will have to first build a diaphragm wall, a box-like structure about 1 m thick, which is essential to prevent settling of soil. According to sources in CMRL, Madhavaram, Murari Hospital, Ayanavaram, Purasawalkam, Chetpet, Royapettah Government Hospital, Greenway’s Road and Thiruvanmiyur will be among the locations where diaphragm walls will be built.
“The trench cutters will arrive from Germany shortly. Work to raise the walls will start in the first week of November. Six months later, when this work is finished, tunnel boring will be launched and the process will go on for a few years,” an official said. The first underground stretch of the phase II project will be opened in 2026 between Madhavaram and Taramani, for which the preliminary work has been kick-started in Madhavaram, Purasawalkam and Greenway’s Road.