 "Kolkata Metro's first India-made tunnel boring machine arrives, tunneling for Purple Line to begin soon")
synopsis
Kolkata Metro’s first largely India-made TBM has arrived, ready to tunnel for the Purple Line despite Kidderpore station land issues. L&T and RVNL push forward on the underground stretch, accelerating Metro expansion with indigenous technology.
A 90-meter-long, 650-tonne tunnel boring machine (TBM), primarily made in India, has reached Kolkata after a 1,653 km journey from Tamil Nadu's Alinjivakkam, marking a major milestone for the city’s Purple Line Metro expansion.
Despite uncertainty over land acquisition for Kidderpore station, authorities have decided to proceed with underground tunneling from Kidderpore to Park Street, reports Times of India. This signals a determined push to complete the much-anticipated 14 km Joka-Esplanade Metro corridor, of which 5 km is underground.
Unlike earlier Metro projects where TBMs were fully imported, the two new tunnel borers were primarily built and assembled in Tamil Nadu, with only four key parts—cutter head, manlock, material lock, and propulsion system—sourced from Germany.
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The TBMs, S-1410A and S-1411A, manufactured at Herrenknecht AG's Tamil Nadu unit, will be used to dig twin tunnels for the underground section. The first stretch to be excavated will span 1.7 km from St Thomas' to Victoria, followed by 950 m from Victoria to Park Street. The final segment between Park Street and Esplanade will use the cut-and-cover method.
The giant machine, transported in 17 trailers, will be directly unloaded into a shaft built inside St Thomas' Boys School and launched from there. The tunnel ring segments, crucial for reinforcing the tunnels, are being produced at L&T's Sarkarpool facility, near Mahestala, which is expected to manufacture around 3,000 segments.
Awarded the Rs 2,447 crore contract by Rail Vikas Nigam Ltd (RVNL), L&T began work in September 2023, first focusing on Victoria station. Casting of tunnel ring segments started in July 2024, setting the stage for full-scale tunneling operations.
While Kidderpore station's fate remains uncertain due to land unavailability at Kolkata Police’s Bodyguard Lines, the tunneling progress ensures the Metro’s underground section moves forward.
This project marks a historic shift toward indigenous Metro construction, reducing dependency on imported equipment and boosting India's infrastructure capabilities.
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