The country’s first undersea tunnel is set to come up as part of the bullet train project.

The National High Speed Rail Corporation Ltd (NHSRCL) has invited bids for the tunneling works for a 21 km long tunnel including a 7 km undersea tunnel for the Mumbai-Ahmedabad High Speed Rail corridor.

The tunnel will be between underground station at Mumbai’s Bandra-Kurla Complex and Shilphata near Kalyan in Maharashtra.

“The 7 km undersea tunnel at Thane Creek (Intertidal Zone) will be the first under sea tunnel to come up in the country,” NHSRCL said in a statement on Friday.

No disturbance

An undersea tunnel will be critical as this area is a protected sanctuary for flamingo and nearby mangroves. Accordingly, rail tracks will be made undersea through a tunnel to ensure there no disturbance to existing ecosystem, said the NHSRCL website.

Railway Minister Ashwini Vaishnaw also tweeted, “Tender floated for 21 km long tunnel; includes India’s first undersea tunnel in Maharashtra for #BulletTrain project.”

The deadline for submission of bids is January 19, 2023.

According to the NHSRCL, the tunnel will be about 25 to 65 metre deep from the ground level and the deepest construction point will be 114 metre below the Parsik hill near Shilphata.

Tunnel Boring Machine and New Austrian Tunneling Method will have to be used to construct the 21 km long tunnel.

Twin track

“The tunnel will be a single tube tunnel to accommodate twin track for both-up and down track. As many as 39 equipment rooms at 37 locations will also be constructed adjoining tunnel location as part of the package,” it said.

Previously, NHCRCL invited bids on July 22 for the design and construction of underground Bandra Kurla Complex high speed rail station. The deadline for submission of bids is October 2022.

The ambitious bullet train project was expected to be completed by 2023 but has run into delays due to problems in land acquisition as well as the Covid-19 pandemic.

The 508 km long Mumbai-Ahmedabad High Speed Rail (MAHSR) project is being executed with the financial and technical assistance from the Government of Japan at a cost of ₹1,08,000 crore.