A massive TBM Durga piercing through the final barrier at maidan Victoria Memorial, as the underground cavern erupted with the ecstatic chants of ‘Vande Mataram’ from jubilant engineers and project workers. (Express photo/Partha Paul)Written by Subhosree ModakA major milestone was etched into the history of the Kolkata Metro Railway on Friday as the Tunnel Boring Machine (TBM) ‘Durga’ successfully made a breakthrough at the under-construction Victoria Metro station around 10.30 am.This engineering triumph marks the flawless completion of the first phase of underground tunneling on the up-line facing Park Street along the Joka to Esplanade Metro line, also known as the Purple Line.As the massive 90-metre-long, 650-tonne machine blew up the soil and pierced through the final barrier into the open reception shaft, the underground cavern erupted with the ecstatic chants of ‘Vande Mataram’ from jubilant engineers and project workers.The momentous event took place in the presence of Prem Sagar Gupta, General Manager of Metro Railway, Kolkata, along with Jakka Prasad Acharya, Consul General of Nepal, and other senior officers from the Kolkata Municipal Corporation, Howrah Police, Rail Vikas Nigam Limited, and L&TAlso Read | Kolkata Metro Purple Line: Land deal with Nepal Consulate clears path for Joka-Esplanade metro workA mission that lasted for 365 daysExactly one year ago, on July 10, 2025, TBM Durga commenced its challenging underground journey from Kidderpore, burrowing 17 metres below the surface near St Thomas’ Boys School. Over the past 365 days, the machine meticulously excavated a 1.7-km-long underground path, travelling safely beneath highly sensitive zones, including Fort William and the PTS station, before safely reaching the premises of the iconic Victoria Memorial without causing any structural damage to the surface.Story continues below this ad“The success brings massive relief and excitement to the Kolkata Metro authorities, especially given the project’s complex history and Kolkata’s notoriously difficult subterranean terrain. The Purple Line project, originally conceived in 2009, has historically faced severe land unavailability hurdles, forcing engineers to start work in a fragmented ‘as-and-when-available’ manner. Furthermore, memories of past disasters in which underground tunneling triggered ground subsidence and structural damage four times in the Bowbazar area had heightened anxieties surrounding the excavation near Victoria Memorial,” said General Manager Gupta.However, Metro sources confirmed that this breakthrough was accomplished with absolute precision, zero surface disruption, and with the utmost safety guaranteed for the underground workforce.Durga, a ‘Make-in-India’ endeavourGeneral Manager Gupta hailed the breakthrough as a monumental achievement for civil engineering and a vital step toward a modern ‘Viksit Bharat’. “Manufactured with parts imported from Germany’s Herrenknecht and assembled in Tamil Nadu as a proud ‘Make-in-India’ endeavour, TBM Durga represents the pinnacle of modern public transportation infrastructure,” he added.Gupta extended his appreciation to the executing teams for maintaining top-tier quality and safety standards while keeping surface traffic completely undisturbed. He also expressed high optimism that Durga’s sibling machine, TBM ‘Divya’, which is currently constructing the downline Jokamukhi line after launching from Kidderpore on October 11, 2025, will meet its deadline to complete its respective stretch by the first week of August 2026.Story continues below this adThe completion of this 1.7-km stretch marks a pivotal transition for the Purple Line, which currently operates an elevated 8-km run from Joka to Majerhat. Work is concurrently underway to finish Mominpore, the final elevated station, before linking the line to its first underground station at Kidderpore. Looking ahead, the overall project aims to span a 14 km corridor from Joka to Esplanade. Following this breakthrough, TBM Durga will eventually be relaunched from the Victoria station to excavate the remaining 900-metre underground stretch toward Park Street, ultimately completing the 2.65 km twin-tube tunnel system and bringing faster, safer, and more sustainable transit to the heart of Kolkata.