A 90-meter-long, 650-tonne tunnel boring machine (TBM), primarily manufactured in India, has arrived in Kolkata after a 1,653 km journey from Tamil Nadu’s Alinjivakkam, marking a major step in the Purple Line Metro expansion. Unlike previous Metro projects that relied on fully imported TBMs, these machines were largely built and assembled in Tamil Nadu, with only four key components—cutter head, manlock, material lock, and propulsion system—sourced from Germany. Despite unresolved land acquisition issues at Kidderpore station, authorities have decided to move ahead with tunneling from Kidderpore to Park Street to keep the project on track.
Manufactured at Herrenknecht AG’s Tamil Nadu unit, the TBMs—S-1410A and S-1411A—will be used to excavate twin tunnels for the underground section of the Joka-Esplanade Metro corridor. The first phase will cover 1.7 km from St Thomas’ to Victoria, followed by a 950 m stretch to Park Street. The final section between Park Street and Esplanade will be built using the cut-and-cover method. The massive TBM was transported in 17 trailers and will be unloaded into a shaft inside St Thomas’ Boys School. Meanwhile, L&T’s Sarkarpool facility near Mahestala is manufacturing around 3,000 tunnel ring segments for reinforcement.
Rail Vikas Nigam Ltd (RVNL) awarded the Rs 2,447 crore contract to L&T, which began work in September 2023, initially focusing on Victoria station. Casting of tunnel ring segments started in July 2024, paving the way for full-scale tunneling operations. While Kidderpore station remains uncertain due to land constraints at Kolkata Police’s Bodyguard Lines, tunneling progress signals steady advancement in the underground section. This project highlights India’s push for self-reliance in Metro construction, reducing dependence on imports and strengthening domestic infrastructure capabilities.
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