KMRC completes 7-storey-deep egress shaft in collapse zone
Times of India | 6 January 2025
12 Kolkata: The East-West Metro project has achieved yet another milestone and has moved forward towards its full run. The 22m-deep passenger egress shaft at Bowbazar's Durga Pituri Lane is now structurally complete. Soon, the entire open space, which is now cluttered with Metro work, will be spruced up and houses that fell in the Aug 2019 tunnelling disaster will be rebuilt.
On Friday, TOI walked down 13 flights of stairs, each with 11 steps, to experience the "climb to safety". The egress shaft, consisting of 143 steps and 14 landings, will allow evacuation of passengers in case of fire or any other emergency. The facility is key to East-West Metro's Esplanade-Sealdah section getting clearance for revenue operations from the Commission of Railway Safety (CRS).
East-West Metro now runs in two disjointed sections – the 9.2km Sector V-Sealdah and 4.8km Esplanade-Howrah Maidan. In Mar 2024, implementing agency Kolkata Metro Rail Corporation (KMRC) skipped the 2.5km Esplanade-Sealdah stretch and launched the Howrah Maidan-Esplanade section despite the lack of a rake maintenance facility on the Howrah side. Trains have since been transported to the Salt Lake depot through the Sector V-bound tunnel. Track-laying for the disaster-hit Howrah-bound tunnel was completed a fortnight ago. This was a major milestone because on Aug 31, 2019, the tunnel boring machine (TBM) digging the tunnel hit an aquifer below Durga Pituri Lane, causing large-scale subsidence. At least 25 houses collapsed.
Now, the last crucial civil construction is also getting completed. The egress shaft built next to the TBM extraction shaft on Durga Pituri Lane juts out like a small house — 4m x 8m. But it is as deep as a seven-storey high-rise.
Built next to the Howrah-bound tunnel, it is linked to the tunnel with a 2m sma-ller passage.
TOI on Nov 2, 2022, reported that "Evacuation shaft may emerge as solution in Bowbazar soft-soil zone". After the subsidence on Oct 14, 2022, in which 12 houses were damaged, contractors ITD ITD-Cementation proposed replacing the three cross-passages planned at various points of BB Ganguly Street with this egress shaft.
Cross passages are small walkways built after every 250m in an underground Metro line to help passenger evacuation during emergencies. After switching tunnels, they would be able to use the walkway next to the tracks to reach the next station. The cross passages, built using the micro-tunnelling method, are mandatory for a Metro line. But then, it was during the construction of a cross passage on Madan Dutta Lane, not far from the Durga Pituri Lane "cave-in zone", that water seepage started on Oct 14, 2022.