123 Kolkata: After five harrowing years, East-West Metro's westward (Howrah-bound) tunnel below Bowbazar is finally complete. The last six metres gap between the two open ends of the subsidence-hit tunnel is now bridged, and the track bed cast. This essentially means the westbound tunnel is now a continuous structure from Howrah Maidan to Sector V. The milestone for the Rs 10,000 crore East-West corridor project, which happens to be India's first under-river Metro, was achieved on Saturday. The corridor is expected to run its entire 16 km length around mid-2025.
"Now there are no doubts about East-West Metro making it to its full length. The most critical hurdle has been crossed and our headaches seem to have disappeared overnight," an engineer from ITD ITD-Cementation, contracted to build the Esplanade-Sealdah section, said.
He remembered the fateful evening of Aug 31, 2019, when the city's most ambitious infrastructure project suffered a major subsidence and tunnelling disaster at Bowbazar, rendering around 750 residents homeless. The tunnel boring machine (TBM) burrowing the westbound tunnel hit a sand aquifer in Bowbazar's Durga Pituri Lane-Syakra Para Lane area, leading to building collapses and cracks in several other structures. The TBM was damaged beyond repair. The incident was followed by at least four more setbacks relating to water seepage and subsidence in the 2.5 km Esplanade-Sealdah section, or more precisely the 200 m area around Durga Pituri Lane. This led to question marks over East-West Metro (Green line) completing the Esplanade-Sealdah section and running its full Howrah Maidan-Sector V stretch. The line now operates in two disjointed sections: 4.8 km Howrah Maidan-Esplanade via Hooghly and 9.2 km Sealdah-Sector V.
With the damaged TBM lying 12 m below the ground, its twin, the TBM digging the eastbound (Sector V-bound) tunnel had to U-turn from Sealdah to complete the remaining 900 m of the tunnelling back to Bowbazar. Implementing agency Kolkata Metro Rail Corporation (KMRC) built a shaft at Durga Pituri Lane's open space (where the 25 houses once stood) to retrieve the damaged TBM. After the second TBM completed its journey, a 38 m yawning gap remained. This part had to be filled in cut-and-cover method. The last six metres of the westbound tunnel gap was bridged on Saturday.
TOI reported on Oct 27, 2023, that track-laying of the westbound tunnel had begun. The work is nearing an end too. Along with work to fix the tunnel rings ovalized in the 2019 subsidence. Currently, the rings of the eastbound tunnel are being retrofitted with semicircular steel liners, following which permanent ballast-less tracks will be re-laid on the eastbound tunnel.
A passenger evacuation shaft is coming up at the same Durga Pituri Lane open site. Officials said 10 out of the 13 flights of the egress shaft, through which passengers will be able to climb up to safety, have been completed.
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