India’s deepest Metro ventilation shaft nears completion

To greater depths: India’s deepest ventilation shaft for East West Metro in Kolkata.

To greater depths: India’s deepest ventilation shaft for East West Metro in Kolkata.  

Kolkata’s East West Metro Project, a mega infrastructure venture connecting the twin cities of Kolkata and Howrah through underground tunnels below the river Hooghly, will have achieved another engineering feat on Monday when it completes India’s deepest Metro ventilation shaft. The shaft goes 43.5 metres below the ground level, equivalent to a 15-storey building. The shaft will not only provide ventilation to the tunnels, but also an exit for evacuation during an emergency.

The evacuation shaft is located at Strand Road near river Hooghly and is situated between the two tunnels.

“This is a marvellous achievement, to successfully complete the 43.5-metre deep Metro ventilation shaft on the bank of river Hooghly. This is India’s deepest Metro ventilation shaft ever constructed by adopting a unique methodology... ,” said Satya Narayan Kunwar, Project Manager, Afcons.

Afcons had been commissioned by the Kolkata Metro Railway Corporation Ltd ( KMRCL) to execute the underground stretch of the East West Metro Project from Howrah Maidan to New Mahakaran station, which includes the tunnels below the river bed. The projects have already achieved a number of significant milestones which are considered engineering marvels. Two tunnels running parallel to each other about 37 metres below the river bed were completed by mid 2017 followed by the Howrah Metro Station, which, at 30 metres below the earth surface, is the deepest metro station in the country.

Afcons officials said the ventilation shaft was another such milestone. The shaft has a 10.3 metre inner diameter circular lining wall of minimum 500 mm thickness, and of concrete grade minimum M40 (a special construction material) circumscribed by 1 metre thick diaphragm walls all around.

‘Innovative techniques’

“The Metro shaft has been constructed adopting innovative engineering techniques and methodology to navigate geological challenges and overcome any impact on Kolkata’s circular railway track along river Hooghly,” Mr. Kunwar said.

The 16.6 km East West Metro Project will connect Howrah on one side of the river Hooghly to New Town Rajarhat in the north eastern fringes of the city on the other side. About 10.8 km of the metro line is underground and the remaining 9.8 km of the project will be through an elevated corridor.

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Printable version | Sep 30, 2020 9:16:36 AM | https://www.thehindu.com/news/cities/kolkata/indias-deepest-metro-ventilation-shaft-nears-completion/article32312211.ece

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