Bengal: TBMs Durga, Divya achieve breakthroughs in Kolkata Metro project

Kolkata, Aug 11 (AHN) Metro Railway, Kolkata, achieved yet another milestone in its ongoing Joka–Esplanade (Purple Line) project after Tunnel Boring Machine (TBM) “Divya” achieved a breakthrough at the Victoria station on Tuesday.

The breakthrough came around noon in the presence of Prem Sagar Gupta, General Manager, Metro Railway; senior officials of Rail Vikas Nigam Limited (RVNL), the executing agency; L&T; and others.

This successful breakthrough marks the completion of the second tunnel from Kidderpore to Victoria stations. Tunnelling work in this section had started on October 11, 2025. TBM “Durga” had already achieved breakthrough at Victoria station on July 10, 2026. With TBM “Divya’s” breakthrough, boring of both tunnels between Kidderpore and Victoria has now been completed, marking substantial progress in the construction of the Joka–Esplanade Metro Corridor (Purple Line).

Officials said the achievement represents engineering excellence, meticulous planning, teamwork and dedicated efforts of all stakeholders. Gupta appreciated the commitment of project personnel who ensured safe and efficient tunnelling while maintaining quality and safety standards, without disturbing surface traffic and normal activities in this densely populated part of the city.

A launching shaft measuring 37 metres in length, 22 metres in width and 17 metres in depth was constructed inside St Thomas School, on Diamond Harbour Road in Kidderpore. The 6.60‑metre diameter TBM was manufactured in Chennai and mobilised to Kolkata in March 2025 for assembly and lowering.

Two TBMs are being used for the construction of twin tube tunnels from Kidderpore to Park Street, beyond which tunnelling will be done by the conventional Cut and Cover method. To cater to the effects of high groundwater table and soft soil conditions in Kolkata, Earth Pressure Balancing (EPB) Type TBMs are being used.

The TBMs, each 95 metres long and weighing nearly 600 tons, are equipped with inflatable seals, pressure transducers, TSG lines, and Backup TSG Pumps as precautions, considering the soil strata of Kolkata. Precast concrete segments of M50 Grade, 275 mm thick, are being used to achieve a finished tunnel diameter of 5.80 metres. The tunnel length between Kidderpore and Victoria is 1.72 km.

The stretch from Joka to Kidderpore will be elevated. Operations have already started between Joka and Majerhat. The Joka–Esplanade Metro Corridor is expected to significantly improve connectivity to the central business district upon completion.

The project has faced hurdles, including land acquisition issues for the Joka depot, delays in permissions from the Local Military Authority (LMA) for use of land on the Kolkata Maidan, and temporary relocation of several clubs on the Maidan. Once completed, the link will connect Joka, home to the country’s first Indian Institute of Management, to the central part of the city.