the National High Speed Rail Corporation Limited (NHSRCL) is reportedly set to launch the tender for the construction of an undersea tunnel on a Mumbai-Ahmedabad bullet train project in India on 9 February.

Claimed to be the first undersea tunnel in India, the 21km tunnel will be constructed at Thane creek between underground stations at Bandra-Kurla Complex and Shilphata in Maharashtra.

Expected to be completed in 60 months, the project will cover a 7km undersea stretch.

The bullet train project, which will cross Dadra and Nagar Haveli, is a 508km corridor between Ahmedabad and Mumbai.

The project will include the construction of a single tube tunnel for the accommodation of a twin track for both-up and down track.

Furthermore, the section will cover the construction of 39 equipment rooms at 37 locations adjoining the tunnel.

Tunnel boring machines (TBMs), which will have a cutter head of 13.1m diameter, will be used in the construction of a tunnel.

Three TBMs are expected to be used to build 16km of the tunnel, while the remaining 5km will be constructed using the new Austrian tunnelling method (NATM).

Besides, the tunnel will be around 25-65m deep from the ground level, while the deepest construction point will be 114 metres below Parsik hill near Shilphata. Last year in December, Japan-based Sojitz and Larsen & Toubro (L&T) consortium won a contract from NHSRCL for the design and construction of the Sabarmati depot for the Mumbai-Ahmedabad High Speed Rail Corridor (MAHSR D-2 Package).