New Delhi: In a significant milestone in the construction of the Kolkata Metro’s Joka-Esplanade corridor, Tunnel Boring Machine (TBM) ‘Divya’ on Tuesday (11 August) successfully achieved breakthrough at Victoria Metro Station.
“The breakthrough took place at around 12:00 hrs in the presence of Shri Prem Sagar Gupta, General Manager, Metro Railway, Kolkata, senior officials of Metro Railway, Rail Vikas Nigam Limited (RVNL), L&T, the executing agency, and other distinguished guests,” Kolkata Metro said in a statement.
This successful breakthrough marks the completion of the second tunnel from Khidderpore to Victoria Metro Station, tunnelling work for which commenced on 11 October 2025, the statement added.
TBM Divya completed boring the tunnel from Khidderpore to Victoria, with a total drive length of 1.72 km.
This comes as TBM ‘Durga’ had already achieved breakthrough at Victoria Metro Station on 10 July 2026.
“With the breakthrough of TBM ‘Divya’, 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),” the metro authority said.
According to the statement, a launching shaft having size of 37 m length x 22 m wide x 17 m deep was constructed inside the Saint Thomas School, Khidderpore for the tunnelling work.
The 6.60 m diameter (outer) TBM was manufactured at Chennai and mobilized to Kolkata in the month of March 2025 for subsequent assembling and lowering.
According to the metro authority, two TBMs are being used for construction of twin tube tunnels from Khidderpore to Park Street, beyond which tunnelling will be done by conventional cut and cover method.
To cater to the effects of high ground water table and soft soil condition in the city of Kolkata, Earth Pressure Balancing (EPB) Type TBMs are being used to burrow the tunnels, it added.
The TBMs, having length of 95 m and weighing approx. 600 tons, are equipped with inflatable seal, pressure transducers TSG Lines and Backup TSG Pump as an additional precaution considering the soil strata of Kolkata.
“Precast concrete segments of M50 Grade having thickness 275 mm are being used to achieve a finished tunnel having 5.80 m diameter,” the statement said.
According to the authority, the Joka-Esplanade Metro Corridor is an important addition to Kolkata’s expanding Metro network and will significantly improve connectivity to the central business district upon completion.
