Metro Rail Kolkata announced the commencement of the Second Tunnelling Work of Purple Line at Khidderpore.

The tunnelling work of the Purple Line from Khidderpore to Victoria had commenced earlier on 10.07.2025. Today, i.e., on 11.10.2025, Mr. Subhransu Mishra, General Manager, Metro Railway, inaugurated the tunnelling boring work by the second Tunnel Boring Machine (TBM) Divya at Saint Thomas School premises, Khidderpore. Senior officials of Metro Railway, Rail Vikas Nigam Limited (RVNL), and Saint Thomas School were also present on this occasion.

A launching shaft measuring 37 metres in length, 22 metres in width, and 17 metres in depth has been constructed inside Saint Thomas School for this work. The 6.63 metre diameter (outer) TBM was assembled in Chennai and moved to Kolkata in March 2025 for assembling and lowering operations.

Two TBMs namely: Durga and Divya are being deployed to construct 2.65 kilometres long twin tube tunnels from Khidderpore to Park Street, the desired break through is expected by December 2026 and March 2027 respectively.

These new generation TBMs are safe and efficient and can bore at the rate of 80 millimetres per minute. Each TBM, measuring 95 metres in length and weighing about 600 tons, is equipped with inflatable seals, pressure transducers, Tail Skin Grease (TSG) lines, and backup TSG pumps as additional safety measures suited to local geological conditions. Precast concrete segments of M50 grade, with 275 millimetres thickness, are being used to construct the finished tunnel with an inner diameter of 5.80 metres.

At present, construction work at Victoria station has progressed almost 66% of its completion of the Top Slab, while Diaphragm Wall (D-Wall) construction at Park Street station stands at 50% completion.

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