Kolkata East-West metro project: Railways completes tunnelling work

The tunnelling work in Kolkata’s East-West Metro Corridor by Tunnel Boring Machine (TBM) with the breakthrough of “Urvi“ at Bowbazar, Kolkata on May 15. With this breakthrough, the Kolkata East-West Metro Project's TBM tunnelling is complete. Because of the century-old buildings, the stretch was difficult for tunnelling work. This difficult 800m tunnel drive was completed successfully amid a pandemic situation using the Covid-19 protocol. The Tunnel Boring Machine ‘Urvi,' which had previously completed the East Bound tunnel from Esplanade to Sealdah in October 2020, was relaunched from Sealdah in January 2021 after necessary refurbishment and inspection to complete the remaining 800 m tunnelling work in the West Bound tunnel from Sealdah to Bowbazar. This tunnelling drive has been completed, and the tunnel boring machine broke through at the Retrieval Shaft in Bowbazar yesterday, on May 15, 2021. This TBM (Urvi) passed beneath the Sealdah Flyover, which was closed to vehicular traffic for three days for safety reasons. After this TBM drive is completed, the tunnel boring machine ‘Urvi', as well as the other stalled TBM ‘Chandi,' will be retrieved from this retrieval shaft at Bowbazar. Excavation of the shaft after ensuring the water-tightness of the shaft and the affected tunnel, as well as retrieval of the TBMs, are intricate activities that must be completed safely and thus take time. After the excavation is completed, both TBMs will be extracted from the shaft in pieces. Following that, the RCC flooring and roofing for the shaft area will be finished, and the shaft top will be backfilled to prepare the ground for above-ground construction. Image SourceAlso read: Kolkata Metro’s East-West Corridor project kicks off Also read: Chennai Metro floats tender for tough tunnelling