The Purple Line, also known as Line 3 of Kolkata Metro, is a 15.08-km corridor that will connect Joka in South Kolkata to Esplanade in the city centre. (Photo: Specially arranged)Tunnelling work on Kolkata Metro’s Purple Line from Kidderpore to Victoria began Thursday, with the launch of a Tunnel Boring Machine (TBM) named ‘Divya’.Metro Railway officials said the machine will tunnel up to Victoria in the first phase, covering 1.7 km, and is expected to break through by May 2026. The entire underground stretch to Park Street is targeted for completion by the end of 2026.The launch shaft—measuring 37 metre in length, 22 metre in width, and 17 metre in depth—has been constructed within the premises of St Thomas’ School, Khidderpore. Two TBMs, ‘Durga’ and ‘Divya’, are being deployed to construct the twin tunnels between Khidderpore and Park Street. Beyond Park Street, the final stretch up to Esplanade will be built using the cut-and-cover method.Durga’s tunnelling was formally flagged off by Metro Railway General Manager Uday Kumar Reddy at the school premises, in the presence of the Consul General of Nepal and senior officials from Metro Railway, Rail Vikas Nigam Ltd (RVNL), the Defence Authority, CMRI Hospital, WBTC and St Thomas’ School.“It is a historic day for the people of Kolkata as the Tunnel Boring Machine has started off. It is a very important and joyous occasion for the city,” Reddy said.The Purple Line, also known as Line 3 of Kolkata Metro, is a 15.08-km corridor that will connect Joka in South Kolkata to Esplanade in the city centre, with a proposed extension to Diamond Park. A portion of the corridor, from Joka to Taratala, is already operational, while the extension to Majerhat has been completed.The line will intersect the Blue Line at Park Street and Esplanade, and the Green Line at Esplanade. It will include a mix of elevated and underground stations, serving locations such as Joka, Taratala, Majerhat, Mominpur, Khidderpore, Victoria, Park Street and Esplanade. Of the total stretch, eight stations are elevated and four are underground.Story continues below this adThe TBMs, each 95 metre long and weighing around 600 tonne, were assembled in Chennai and brought to Kolkata in March this year for final assembly and lowering. They are Earth Pressure Balancing (EPB) type machines, designed to tackle Kolkata’s high groundwater table and soft soil conditions. Metro officials said the machines are equipped with inflatable seals, pressure transducers, Tail Skin Grease (TSG) lines and backup pumps to manage soil pressures. Precast concrete segments of M50 grade and 275 mm thickness are being used to create tunnels with a finished internal diameter of 5.8 metres.Construction firm Larsen & Toubro (L&T) is executing the 2.65-km underground section from Kidderpore to Park Street. The first TBM drive—from St Thomas’ School to Victoria—is 1.7 km long. The second leg, from Victoria to Park Street, will cover 950 metre.The final underground station of the corridor is likely to be located near Eden Gardens’ Gate No 1, adjacent to the Mohun Bagan football ground.Sweety Kumari reports from West Bengal for The Indian Express. She is a journalist with over a decade of experience in the media industry. Covers Crime, Defence, Health , Politics etc and writes on trending topics. With a keen eye for investigative and human-interest stories. She has honed her craft across diverse beats including aviation, health, incidents etc. Sweety delivers impactful journalism that informs and engages audiences. Sweety Kumari is a graduate of Calcutta University with an Honors degree in Journalism from Jaipuria College and a PG in Mass Communication from Jadavpur University. Originally from Bihar, she is brought up in Kolkata and completed her education from Kendriya Vidyalaya SaltLake. Multilingual, Sweety is fluent in English, Hindi, Bengali, and Maithili. She started her career as an Entertainment and lifestyle journalist with a newsportal in Kolkata. She is working with The Indian Express for 8 years now. ... Read MoreStay updated with the latest - Click here to follow us on Instagram© The Indian Express Pvt LtdTags:Kolkata