The Tunnel Boring Machine (TBM) S-616, nicknamed Urvi, deployed for last leg of East-West Metro Tunnelling has now completed half of its journey towards building the final 800m west-bound tunnel. On Tuesday, 6th April, Urvi crossed the 400m mark and had covered 425m at the end of the day, having made 283 rings.
Urvi’s final assignment involves building 553 tunnel rings. On Wednesday, 7th April, it finished making 287 rings and had covered 430m from the Sealdah Metro station. It is now 35m from the Bank of India building on BB Ganguly Street. Engineers of Kolkata Metro Rail Corporation (KMRC), implementing agency of the 16km Line 2, hoped the TBM would cross Bank of India in the next few days and complete its job by mid-May.
On January 4, Urvi, started its journey from below Sealdah station to bridge the last 800m gap of the westward tunnel. It had to take a month’s break on January 27 to create space to shove its own 75m length inside. Only the main 9m of the machine, comprising cutter-head, front and middle bodies and tailskin could be lowered below the ground at the initial stage. The rest “backup gantry”, were added to prepare for the “main” drive.
From March 1, tunnelling resumed and the “main” drive started. On October 9 last year, Urvi dug the east-bound tunnel till Sealdah station. It then started filling the last section of the west-bound tunnel that TBM Chundi had left incomplete after hitting an aquifer at Bowbazar on August 31, 2019.