The National High Speed Railway Corporation Limited (NHSRCL) has invited bids for the construction of a 21-km-long tunnel, 7 km of which will be under the sea, for the Mumbai-Ahmedabad High Speed Rail Corridor.

16 km of the tunnel will be built via TBM and 5km with NATM. 3 Tunnel Boring Machines will be used with a cutterhead of 13,1 metres.

https://www.tribuneindia.com/news/nation/mumbai-ahmedabad-bullet-train-project-nhsrcl-invites-bids-for-construction-of-21-km-long-underground-tunnel-434622