Mumbai-Ahmedabad Bullet Train: Afcons wins bid to construct 21 km underground tunnel

Afcons Infrastructure has emerged as the lowest bidder to construct 21-km underground package C-2 of the Mumbai-Ahmedabad Bullet Train project.

“The National High Speed Rail Corporation Limited (NHSRCL) has opened financial bids for the construction of 21km-long tunnel including India’s first 7km-long undersea tunnel for the Mumbai-Ahmedabad High Speed Rail Corridor under MAHSR C-2 package on Friday and M/s Afcons Infrastructure Limited have quoted lowest bid," said spokesperson of NHSRCL. The technical bids of this tender were opened on February 9, 2023.

“The tunnel will be between underground station at Bandra-Kurla Complex and Shilphata. The 7km (approx) undersea tunnel at Thane Creek (Interdidal Zone) will be the first undersea tunnel to come up in the country,” said an official of NHSRCL adding that the tunnel will be a single tube tunnel to accommodate twin track for both-up and down track. Thirty-nine equipment rooms at 37 locations will also be constructed adjoining tunnel location as part of the package.

Boring machines with 13.1m diameter to be used

To construct this tunnel, tunnel boring machines (TBMs) with a cutter head of 13.1m diameter will be used. Usually 5-6m diameter cutter heads are used for urban tunnels in MRTS–Metro system.

“Three TBMs will be used to make about 16km of the tunnel portion and the remaining 5km will be through New Austrian Tunnelling Method (NATM).

Tunnel to be 25-65m below ground

This tunnel will be about 25-65m deep from the ground level and the deepest construction point will be 114m below the Parsik Hill near Shilphata,” he said.

Three shafts at BKC (under package C1), Vikhroli and Sawli at approximate depths of 36, 56 and 39m depths, respectively, will facilitate the construction. Inclined shaft of 42m at Ghansoli and tunnel portal at Shilphata will facilitate the construction of approximately 5km of tunnel through NATM tunnelling method.