Rain delays TBM Urvi’s breakthrough

Two days of heavy rain delayed tunnel borer Urvi’s planned breakthrough on Thursday, 13th May 2021. Breakthrough is needed at the end of a tunneling when the tunnel boring machine (TBM) is made to punch through a wall that integrates the tunnel with an underground Metro station. In this case, a diaphragm wall has been built to integrate the two sections of the same tunnel.

One section covers around 1.6km from Esplanade till Bowbazar’s Durga Pituri Lane. Another 800m stretches from Sealdah station till the same spot. The two sections will be bridged today, Sunday 16th May 2021. The breakthrough will finally mark the completion of the TBM-driven tunnels of the Rs 8,575.98 crore East-West Metro project.

Urvi, as TBM S-616 is nicknamed, should cover the last 10m by Saturday night or Sunday afternoon (Friday being a holiday). Thus, Kolkata’s biggest infrastructure project would achieve its most significant milestone ever.

Despite several staff members of contractors ITD ITD-Cementation infected with Covid-19, Urvi was veering towards the Thursday deadline for the breakthrough. By evening it would have punched the diaphragm wall below Bowbazar’s Durga Pituri Lane. But heavy downpour on Tuesday, 11th May and Wednesday 12th May came in the way. Water started seeping in through the Sealdah station shaft, from where the 800m tunnel till Durga Pituri Lane starts. “The hi-tech electrical equipment was at risk. We had to stall the digging temporarily. Now the water has dried up and the TBM has been re-initiated,” an engineer involved in the project said.

Officials of Kolkata Metro Rail Corporation (KMRC), implementing agency of the 16km East-West Metro corridor project that will eventually join Sector V with Howrah Maidan, said they were eyeing a Sunday afternoon breakthrough. The ITD ITD Cementation is contracted to build the last 2.45km Esplanade-Sealdah stretch of the East-West Metro. On January 4 this year, Urvi started its journey from below Sealdah station to bridge the last 800m gap of the westward tunnel.

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