650-tonne TBM Reaches Kolkata for Purple Line Tunneling

A 90m-long, 650-tonne tunnel boring machine (TBM), mostly made in India, has arrived in Kolkata after a 1,653 km journey from Tamil Nadu's Alinjivakkam. Despite land acquisition issues at Kidderpore station, Metro authorities have decided to proceed with underground tunneling from Kidderpore to Park Street.
The TBM will first excavate a 1.7 km stretch from St Thomas' to Victoria, followed by a 950m drive from Victoria to Park Street. The Park Street to Esplanade section will be constructed using the cut-and-cover method.
L&T, awarded the ₹2,447 crore underground package by Rail Vikas Nigam Ltd (RVNL), has commenced full-scale work. While some critical components—like the cutter head, manlock, material lock, and propulsion system—were sourced externally, most of the two TBMs were built indigenously. Though manufactured by Herrenknecht AG's Tamil Nadu unit, they were not entirely assembled outside India.