The 502 meter-long tunnel under the Hooghly River is dug jointly by Afcons Transtonnelstroy and Kolkata Metro Railway Corporation Ltd.
India Today reports that the underwater tunnel was constructed by making use of Rachna, a massive tunnel-boring machine (TBM), which was brought from Herrenknecht AG plant in Schwanau, Germany.
The project faced several delays since it started, owing to issues related to slum relocation, land allocation and route alignment. But now, the completion of the boring of this tunnel ahead of deadline comes as wonderful news.
The final commissioning of the metro line is expected by the end of 2019 and the route will be operational after that.