Kolkata: The final cross-passage in the subsidence-prone Esplanade-to-Sealdah section of the East-West Metro has been successfully completed, marking a significant milestone in the project. This achievement paves the way for connecting the two disjointed sections of the Green Line, bringing the entire 16.6km corridor closer to operational status.
The completion of the cross-passages is crucial for the safety and functionality of the underground metro line. These small tunnels, built at 250m intervals, allow passengers to cross between the main tunnels in emergencies such as fires. Despite their importance, the Kolkata Metro Rail Corporation (KMRC) and contractors ITD-ITD Cementation had to adopt a cautious approach due to the area’s history of ground subsidence. Work on the final cross-passage, designated 5B, was particularly challenging. On April 18, water seepage was detected at two locations during micro-tunnelling operations below Hind on Ganesh Chandra Avenue. This led to an immediate halt in construction. Intensive chemical and cement grouting were conducted over three days to stabilise the area, allowing micro-tunnelling to resume on April 22. As a precaution, a high-rise building at 1A, Subodh Mullick Square was evacuated for a week. “The priority was to prevent ground settlement and avoid damage to nearby buildings,” an engineer involved in the project explained. This careful approach ensured that the work proceeded without further incidents of subsidence.
KMRC had initially planned eight cross-passages in the Esplanade-Sealdah section, but three were scrapped following a significant subsidence event on October 14, 2022. The project has faced multiple subsidence incidents since 2019, necessitating alterations to the original plans. The site for cross-passage 5B, originally under Nirmal Chunder Street, had to be relocated due to unstable soil conditions. The new site, beneath a cinema, also required extensive grouting to ensure stability. Using the New Austrian Tunnelling Method (NATM), a high-tech micro-tunnelling process began on April 16. Despite initial success, water seepage was detected within four days, prompting another halt and evacuation of a nearby building with a weak foundation. Work resumed cautiously on April 22, and the project continued without further subsidence issues.
With the cross-passages now complete, work on the Esplanade-Sealdah stretch is expected to conclude shortly. Once finished, this will connect the currently operational sections between Sector V and Sealdah and between Howrah Maidan and Esplanade. This integration will enable full services across the entire East-West Metro corridor, significantly enhancing Kolkata’s urban transit infrastructure. This development underscores the meticulous engineering and careful planning required to overcome the challenges posed by urban infrastructure projects in geologically sensitive areas. As Kolkata prepares for the full operation of the East-West Metro, the city’s residents can look forward to a more connected and efficient transit system.
