India’s first underwater rail tunnel completed in less than half the time allocated for it

KOLKATA: The deadline was July this year. But the engineers and employees of Afcons Transtonnelstroy and Kolkata Kolkata Metro Railway Corporation Ltd, the two entities implementing the East West Metro have completed boring the country’s first tunnel under the Hooghly river for establishing metro link between Howrah and Kolkata.

Rachna, a giant tunnel-boring machine (TBM), was deployed to dig the underwater tunnel that runs a length of 502 metres under the river.

Afcons Transtonnelstroy is an Indo-Russian joint venture. The machine was brought from Herrenknecht AG plant in Schwanau in Germany.

The entire project is 16.6 km long, out of which 10.8 km runs under the ground. Of this 10.8 km, 502 metres is under the water. The project connects Howrah to the west and Salt lake to the east.

Digging this tunnel was the most difficult and critical task in the entire project. The job was completed in a time of one month and six days, about 50 days ahead of schedule. The project is built by Afcons Transtonnelstroy and implemented by KMRCL.

A senior official of KMRCL, who did not wish to be named, said that the work digging the tunnel started on April 14, 2016. “The entire credit for completion of the work much before scheduled deadline goes to the 250 odd engineers, technicians and workers, who have worked day and night to complete the task. On an average we have dug 35 to 40 metres every day, following which the digging of the entire tunnel length of 520 metres was completed in little more than a month,” the KMRCL officer said.

The stretch of 16.6 km will have 12 stations, six of which will be under the ground, while the remaining six stations will be on elevated tracks. The final commissioning of the project commissioning of the project is expected by December 2019, following which it will be operational.

“Considering the pace at which we completed the most difficult task of creating the underwater tunnel, we hope to meet the deadline of final commissioning,” the KMRCL official said.

The total project cost is $750 million, which roughly comes to around Rs 5,000 crores. Since the beginning, the project was held up several times mainly due to land allocation, slum relocation and route alignment problems among others.

The project was originally slated to be completed by 2012. It was first postponed to 2015 and finally to December 2019.