New Delhi, May 16 (IANS): Amidst Covid-19 situation following protocol related to the pandemic, Indian Railways on Sunday announced that it has completed 800 metre challenging tunneling work in East West Metro Corridor from Sealdah to Bowbazar in Kolkata.

With this breakthrough the entire tunneling for the Kolkata East-West Metro Project is completed.

"The stretch was difficult for tunneling work as it had century old buildings. This challenging tunnel drive of 800 m has been completed successfully amidst this pandemic situation following COVID-19 protocol," said the Ministry of Railways.

The Tunnel Boring Machine 'Urvi' which had earlier completed East Bound tunnel from Esplanade to Sealdah on October 9 last year was relaunched from Sealdah after necessary refurbishment and inspection on January 9 this year to complete the balance 800 m tunneling work in West Bound tunnel from Sealdah to Bowbazar.

This drive of tunneling has been completed and the tunnel boring machine break through at Retrieval Shaft at Bowbazar was achieved on Saturday.

This TBM (Urvi) has passed below Sealdah flyover also for which vehicular movement on the flyover was closed for three days for safety reasons, the Ministry said, after completion of this TBM drive, the tunnel boring machine 'Urvi' along with the other stalled TBM 'Chandi' will be retrieved from this retrieval shaft at Bowbazar.

Excavation of shaft after ensuring the water tightness of the shaft and the affected tunnel and retrieval of the TBMs are intricate activities which have to be done safely and hence will take time.

After completion of entire excavation, both the TBMs will be retrieved in pieces from the shaft. The RCC flooring and roofing for the shaft area will be completed thereafter and the shaft top will be backfilled to prepare the ground for overground construction.