‘Durga’ starts working under Purple Line of Kolkata Metro

Kolkata: There are 72 days still left for Mahalaya but Durga has started her journey — not from the heavens, rather beneath the earth. It is not the deity but the tunnel boring machine S1410 — used for the Purple Line metro works — nicknamed ‘Durga.' The tunnelling for the 5 km Mominpur-Esplanade section of the Purple Line began on Thursday. The machine started burrowing at Kidderpore to build one of the twin underground tunnels."This is a historic day for Kolkata. Tunnelling starts days after the state govt finally allowed Metro to use land at Alipore Bodyguard Lines for key Purple Line station construction at Kidderpore," Metro Railway general manager, P Uday Kumar Reddy said, after pressing a button for the giant machine to roll below the 236-year-old St Thomas' Boys' School at Kidderpore. Sibling TBM Divya (S1410A), being assembled inside the same 17 m-deep launching shaft, will start digging a month later to maintain a 150 m gap with Durga.The duo's first stop will be at the Victoria Memorial, across 1.7 km. The 95 m long borers will be relaunched from the Victoria Metro station box for another 950 m of tunnelling to Park Street, beyond which the 640 m stretch to Esplanade will be built using the cut-and-cover method (without TBMs). "Durga should reach Victoria by May 2026 and Park Street by Dec 2026," Vipin Kumar, chief project manager of the project implementing agency, Rail Vikas Nigam Ltd (RVNL), said. Other RVNL officials, including executive director (ED) Amit Tandon, attended the Puja to mark the occasion.The Purple Line (14 km Joka-Esplanade corridor) now runs on an elevated 8 km Joka-Majerhat stretch. It will duck underground near Ekbalpore, not far from the last elevated station at Mominpore. TOI reported on Mar 9 that mammoth 650-tonne tunnel boring machine had completed 1,600-km journey from Tamil Nadu to Kolkata. Guided by superior technology, the earth pressure balance (EPB) machines can dig through rock, soil or sand to build tunnels with precast segment rings.Traditionally, TBMs are given feminine names from the time when Saint Barbara, patron saint of miners, would be invoked to save those working with explosives for underground construction in the 16th century. "In the land of Maa Durga, it only seemed appropriate to christen a TBM after the deity. The twin TBM is called Divya, which, in Sanskrit, stands for divine," an official explained.The TBMs were assembled in Herrenknecht's Alinjivakkam unit in Tamil Nadu. "Durga, with a 6.6 m outer diameter arrived in March and was subsequently lowered in the St Thomas' launching shaft," Kumar said. Extra precautions are being taken to ensure the TBMs dig safely, taking note of the East-West Metro tunnelling fiasco in Bowbazar, the Metro GM said. On the Orange line's Chingrighata hurdle, he said, "The railway minister recently requested the state govt to take the project forward. The cost is soaring. It's the taxpayers' money."