E-W Metro work: Traffic block at Nirmal Chunder St near Wellington from Aug 10
Times of India | 30 July 2023
KOLKATA: The entire width of Nirmal Chunder Street will be blocked near Wellington Square for eight months from August 10 to enable construction of a passenger ventilation shaft in the East-West Metro line that had to be abandoned in an earlier attempt following cave-in fears. This time, the ground below will be frozen before the shaft is dug.
"Traffic block has been given from August 10 for the crucial East-West Metro work. No vehicles will pass through this section of Nirmal Chunder Street (Lenin Sarani to Wellington crossing) while the Metro work is underway," an official from the Sealdah traffic guard told TOI on Saturday.
Ground-frosting, which involves continuous refrigeration by pumping nitrogen into boreholes of soil for drilling operations, will be used for micro-tunnelling operations for the first time in India to stabilize the soil.
On barricading the site from August 10, Kolkata Metro Rail Corporation and contractor ITD ITD-Cementation will map the precise locations of underground utilities and clear the coast for ground-freezing. A 33KV CESC cable will be shifted out of the 6m radius of the zone. The underground sewer line below Nirmal Chunder Street will also be insulated. Once utilities are out of the way, ground-freezing will be done and a cross passage will be built to link the twin tunnels below Nimal Chunder Street with the ventilation shaft at Subodh Mullick Square. The entire exercise will take eight months, engineers said.
The project has been stuck in Bowbazar since the August 2019 subsidence which led to large-scale evacuation of residents. After two more cave-ins last year, ITD suspended the work to build cross passages below Nirmal Chunder Street last December. ITD proposed the freezing technique by Norway-based ground freezing expert GeoFrost. Linde will be supplying the oxygen needed. KMRC realized that the technique, though costly (around Rs 60 crore), was the only way to take the project forward.