Kolkata Purple Line Clears Another Underground Hurdle
Kolkata’s Purple Line has crossed another major construction threshold, with the second tunnel between Khidderpore and Victoria completed on Tuesday. The breakthrough brings the Joka–Esplanade Metro corridor closer to its central-city connection, with implications for daily commuting, road congestion and the city’s longer-term shift towards higher-capacity public transport.
Tunnel Boring Machine (TBM) Divya completed a 1.72-km underground drive from Khidderpore to Victoria after tunnelling began on October 11, 2025. The achievement follows the breakthrough of the parallel tunnel by TBM Durga on July 10, meaning both underground tubes on this section have now been bored.The engineering challenge is significant because the route passes through a densely built part of Kolkata where construction has to contend with soft ground and a high groundwater table. The machines use Earth Pressure Balance technology, which helps maintain pressure at the tunnel face and limit ground movement during excavation. Precast concrete segments are being installed to form the permanent tunnel lining.For residents, the importance of the Kolkata Purple Line will ultimately depend less on the tunnelling milestone itself and more on how effectively the completed corridor connects neighbourhoods with employment, education and commercial destinations. The Joka–Esplanade route is planned to extend the Metro network from southern Kolkata towards the central business district, creating an alternative to road-based journeys across some of the city’s busiest corridors.
The underground approach also has an urban-planning advantage. Where surface space is constrained by established neighbourhoods, heritage assets, roads and existing activity, tunnelling can reduce the need for continuous above-ground construction. That does not remove environmental or social risks, however. Ground settlement, construction safety, access around work sites and protection of older structures remain important considerations as the project progresses.The Kolkata Purple Line is part of the wider Joka–Esplanade corridor, whose completion is expected to strengthen links between southern parts of the metropolitan area and central Kolkata. The next stages will involve completing the remaining underground works towards Park Street and integrating the new infrastructure into the operational Metro network.
For Kolkata, the real measure of success will come when construction translates into reliable, accessible and affordable journeys. Completing tunnels is a crucial infrastructure step; delivering a well-connected public transport system that reduces dependence on private vehicles will determine its wider civic and environmental value.
