National High Speed Rail Corporation Limited said that the Afcons Infrastructure Limited has quoted the lower amount among two technically qualified financial bids for the construction of a 21-kilometre tunnel, including 7 kilometres under the sea, as part of the Mumbai-Ahmedabad bullet train project.
This tunnel will stretch from the proposed underground station at Bandra Kurla Complex in Mumbai to Shilphata in neighbouring Thane district, the NHRSCL said, adding it had received bids from Afcons Infrastructure Limited and Larsen & Toubro Limited.
The tunnel will be a single-tube twin-track tunnel having a diameter of 13.1 metres. Out of 20.37 km, 15.42 km of tunnelling will be carried out with three TBMs (Tunnel Boring Machine) and the remaining 4.96 km will be built using New Austrian Tunnelling Method (NATM). The depth of the tunnel will vary from 25 metres to 65 metres, the NHRSCL said in a release.
The tunnel will cross Thane creek and the survey work under the creek was done using underwater static refraction technique. The deepest construction point will be 114 metres below Parsik Hill near Shilphata, an NHSRCL spokesperson said. The high speed corridor between Mumbai and Ahmedabad is coming up at a cost of Rs 1.08 lakh crore.