12 years and several stumbling blocks later, E-W Metro tunnelling work is complete

KOLKATA: The tunnelling work of East-West Metro was completed on Saturday evening, a day ahead of the scheduled ‘breakthrough’ as engineers revved up the tunnel boring machine to reach the landmark before restrictions kicked in on Sunday.
Among the most ambitious Metro projects in the country, the Rs 8,576-crore East-West Metro links the twin cities of Kolkata and Howrah through a tunnel that runs below the Hooghly riverbed. While the tunnelling was scheduled to be completed months earlier, an accident in August 2019 that led to house collapses in Bowbazar delayed the project.
On Saturday afternoon, TBM Urvi covered the final 10 metres to pierce the diaphragm wall to complete the Howrah-bound tunnel. Last October, it had completed the Kolkata-bound tunnel and then turned around to complete the 800 metres to the cave-in zone where TBM Chandi had stalled after hitting an aquifer leading to subsidence. Last year, a shaft was built to extricate Chandi so that Urvi could complete the tunnel.
Kolkata Metro Railway Corporation (KMRC), the implementing agency of the 16km East-West Metro corridor project had originally scheduled to cross the final barrier on Sunday afternoon.
The East-West Metro project has crossed several milestones along its journey. The most significant was on May 23, when TBM Rachna completed the tunnelling under the Hooghly in 36 days. Sibling TBM Prerna followed and finished the other river tunnel on June 21, 2017.
But it was the last lap of tunnelling that proved the most challenging as the TBMs bored under a congested neighbourhood with crumbling buildings and met with an accident. Ironically, it was over the alignment of the same section that the project was delayed for several years in its infancy.