In a major boost for urban transit connectivity in West Bengal, the Kolkata Metro’s Purple Line achieved a significant engineering milestone on July 10, 2026. Tunnel Boring Machine (TBM) ‘Durga’ successfully completed its first phase of tunnelling, marking a vital step forward for the Joka-Esplanade Metro Corridor project aimed at bridging the gap between south and central Kolkata.
Key highlights of the project progress include:
– TBM Durga completed a challenging **1.7-kilometer underground stretch**.
– The route successfully navigated beneath the **Royal Calcutta Turf Club heritage zone**.
– Tunnelling work commenced on **July 10, 2025**, from a shaft at St. Thomas’ Boys School.
– The twin tunnel project is officially expected to be completed by **March 2027**.
Overcoming Engineering Challenges
The breakthrough followed exactly one year of intensive work. The stretch between Kidderpore and Victoria Memorial is widely considered one of the most technically demanding segments of the entire corridor due to the city’s complex soil structure. Union Minister for Railways, Ashwini Vaishnaw, praised the feat, describing the project as a display of **”engineering excellence beneath the city.”** The event was marked by a celebration attended by senior officials from Metro Rail, Kolkata, alongside representatives from Rail Vikas Nigam Limited (RVNL) and the civil contractor, Larsen & Toubro (L&T).
Technical Specifications and Future Outlook
The underground section of the Purple Line stretches for **5.05 kilometers** from Mominpur to Esplanade. To manage Kolkata’s unique challenges, such as soft soil and a high groundwater table, engineers are utilizing advanced Earth Pressure Balancing (EPB) TBMs. These machines are massive, measuring **95 meters in length and weighing approximately 600 tonnes**.
Work on the parallel tunnel is already well underway, with TBM ‘Divya’ having commenced its journey on October 11, 2025. As these twin tunnels progress toward Park Street, the completion of this link promises to significantly reduce travel time and traffic congestion for thousands of daily commuters in the city. With the current momentum, the project remains on track to meet its March 2027 completion target, further solidifying Kolkata’s reputation for complex subterranean infrastructure development.