This groundbreaking initiative involves the construction of a 21-kilometer-long undersea rail tunnel connecting the underground station at Bandra-Kurla Complex to Shilphata in Maharashtra. The tunnel will be designed as a single-tube structure, accommodating twin tracks to facilitate the seamless movement of trains. Additionally, as part of the project, thirty-nine equipment rooms will be strategically built at 37 different locations adjacent to the tunnel.

To conquer the 7-kilometer stretch beneath Thane Creek, situated below sea level, the TBM equipped with the 13.1-meter-wide cutter head will be deployed. In total, three TBMs will be employed for this purpose.

The tunnel's depth will range from 25 to 65 meters below ground level. To support the construction, three shafts will be created at BKC, Vikhroli, and Sawli in Thane, reaching approximate depths of 36 meters, 56 meters, and 39 meters, respectively.

The National High Speed Rail Corp (NHSRCL), a specially established organisation responsible for overseeing the bullet train project, has signed an agreement with M/s Afcons Infrastructure Ltd to undertake the construction of this remarkable 21-kilometer stretch, including the 7-kilometer undersea rail tunnel.