National High-Speed Rail (NHSRCL) has launched a tender process to build an undersea rail tunnel for the Ahmedabad-Mumbai bullet train project.

The 21km-long undersea rail tunnel will stretch from Bandra Kurla Complex to Kalyan Shilphata in the state of Maharashtra.

It would include a 1.8km section on the sea bed and 7km under the Thane creek.  The remaining section will be built under mangroves on the two sides of the creek.

In addition to building the tunnel, the scope of works includes testing and commissioning double line high-speed railway using a tunnel boring machine (TBM) and the Austrian tunnelling method for the project.

“It would include a 1.8km section on the sea bed and 7km under the Thane creek.”

The works are expected to be completed within three and a half years.

Bidding process will be open till 22 August. NHSRCL will also conduct a pre-bid meeting on 24 May for interested bidders.

A technical bid will be opened on 23 August in the presence of representatives of the bidders.

A geotechnical investigation to construct the undersea tunnel area was completed last year. The survey was carried out by a joint team comprising engineers from NHSRCL, RITES and Japan’s Kawasaki Geological Engineering.

An NHSRCL official told The Times of India that it has received environmental clearances from most of the relevant authorities, with others providing principal consent for the project.

The 508km-long Ahmedabad-Mumbai bullet train project is scheduled to become operational in 2022. In 2017, the foundation stone of the project was laid by India Prime Minister Narendra Modi and his Japanese counterpart Shinzo Abe.