Kolkata Metro achieved another major breakthrough on 11 August 2026 when Tunnel Boring Machine (TBM) ‘Divya’ successfully broke through at Victoria Metro Station. The breakthrough, which took place around 12 noon, marks the completion of the second underground tunnel between Khidderpore and Victoria on the Joka-Esplanade corridor also known as the Purple Line.
The event was conducted in the presence of Metro Railway General Manager Prem Sagar Gupta, along with senior officials from Metro Railway, the executing agency L&T and Rail Vikas Nigam. Railway Minister Ashwini Vaishnaw also noted the milestone, posting on X, “One more tunnel breakthrough! Kolkata.”
With this achievement, both parallel tunnels on the Khidderpore-Victoria stretch are now complete. This development represents substantial progress in the construction of the Joka-Esplanade Metro Corridor.
Details of the latest breakthrough
TBM Divya commenced tunnelling on 11 October 2025 from a launching shaft inside St Thomas in Khidderpore. It covered a drive length of 1.72 km and reached Victoria on 11 August 2026 after about 10 months of work.
As per the official release by the Metro Railway, Kolkata, the successful breakthrough of TBM ‘Divya’ “marks the completion of the second tunnel from Khidderpore to Victoria Station”. The tunnelling of both tunnels between Khidderpore and Victoria has now been successfully completed, marking substantial progress in the construction of the Joka-Esplanade Metro Corridor (Purple Line).”
All about the first tunnel by TBM Durga
The first tunnel was completed a month earlier. TBM ‘Durga’ began work on 10 July 2025 from the same shaft and achieved the first breakthrough at Victoria on 10 July, 2026, exactly one year later. That milestone marked the completion of one of the two underground drives between Khidderpore and Victoria and was recognised as a key step in boosting Kolkata’s metro network. Officials had noted that the tunnelling was conducted with minimal disruption to surface traffic.
How the tunnels were built
A launching shaft measuring 37 metres long, 22 metres wide and 17 metres deep was constructed inside St Thomas School. Each TBM is about 98 metres long, weighs around 600 tonnes and has an outer diameter of 6.60 metres. The machines were manufactured in Chennai and brought to Kolkata in March 2025.
Special Earth Pressure Balancing (EPB) TBMs were used to handle Kolkata’s soft soil and high groundwater. They were fitted with safety features including an inflatable seal, pressure transducers and backup systems. The finished tunnels will have a diameter of 5.80 metres and are lined with 275 mm thick M50-grade concrete segments.
Two TBMs are being used to build twin tunnels from Khidderpore to Park Street. Beyond Park Street, the remaining work will follow the cut-and-cover method.
Kolkata Purple Line Update
The TBMs will now be retrieved for maintenance and later relaunched from Victoria towards Park Street (about 900 metres). Once the full corridor is ready, the Purple Line will link southern Kolkata with the central business district.
Better connectivity across the city
The breakthrough is described in the official release as “a testimony to the engineering excellence, teamwork, meticulous planning and dedicated efforts of all stakeholders related to the project. It has also been termed “another important step towards strengthening Kolkata’s urban transport infrastructure and providing commuters with faster, safer, reliable and sustainable infrastructure for Kolkata.
The Joka-Esplanade corridor is expected to offer faster, safer and more reliable journeys, providing an alternative to road travel and helping ease pressure on the city’s transport network.