Kolkata Metro’s Purple Line has achieved a major tunnelling milestone with Tunnel Boring Machine (TBM) ‘Divya’ breaking through at the under-construction Victoria Metro station, completing the second underground tunnel between Khidderpore and Victoria on the Joka–Esplanade corridor. The breakthrough on August 11 marks the completion of the first phase of underground tunnelling on this section.
The breakthrough follows nearly 10 months of tunnelling, with Divya covering a 1.72-km drive from a launching shaft at St Thomas’ School in Khidderpore to Victoria. The machine began excavation on October 11, 2025, working beneath one of Kolkata’s most densely developed urban areas.
The tunnelling work has been particularly challenging because it is being carried out beneath central Kolkata, where underground construction requires careful control of ground conditions and close monitoring of surface structures. The project has employed Earth Pressure Balance (EPB) tunnelling technology, allowing excavation and ground-pressure management to be carried out simultaneously in the city’s complex subsurface environment.
The completed tunnels will form part of the Majerhat–Esplanade section of the Purple Line, extending the existing Joka–Majerhat metro corridor deeper into central Kolkata. The corridor is being developed to provide a direct rapid-transit connection between the city’s southern suburbs and important central locations.
The Victoria station itself is an important component of this underground section, located close to the Victoria Memorial and the central business and cultural districts. Its eventual integration into the network is expected to improve access to central Kolkata while providing an alternative to heavily congested road corridors.
The breakthrough also demonstrates the growing role of advanced tunnelling technology in Kolkata’s metro expansion. Unlike elevated metro construction, underground sections in established urban areas require specialised equipment capable of operating within constrained spaces while maintaining strict control over settlement, vibration and ground stability.
The latest achievement does not, however, mark the completion of the entire Purple Line. Further construction and systems work remain on the route towards Esplanade, including station construction, track installation, signalling, electrical systems and other finishing activities before the new section can enter passenger service.
For Kolkata’s wider urban transport network, the milestone is significant. The Purple Line’s expansion is intended to strengthen north-south connectivity, reduce dependence on road-based transport and provide a faster public-transport link between growing southern neighbourhoods and central Kolkata.
The successful completion of the twin tunnels between Khidderpore and Victoria therefore represents more than a tunnelling achievement. It marks the transition of a technically demanding underground section from excavation towards the next stage of metro construction, bringing the Purple Line closer to its planned extension into the heart of Kolkata.