21-km long tunnel to be dug between BKC, Thane for bullet train

Three tunnel boring machines will be used to dig about 16 kms of the tunnel and the remaining five kilometers will be through New Austrian Tunnelling Method (NATM). The channel will be 25 to 65 meters deep, with a single deepest construction point 114 meters below Parsik Hills in Thane.

Mumbai: A 21-km long tunnel will soon be dug between Bandra Kurla Complex and Shilphata station in Thane on the Mumbai-Ahmedabad bullet train route. It will run undersea for seven kilometers — which will make it the longest undersea tunnel in India.

FILE - In this Sept. 24, 2014 filephoto, passengers get on the Shinkansen high-speed train at Tokyo station in Tokyo. Indian Prime Minister Narendra Modi hopes the visit this weekend by Shinzo Abe, starting Friday, Dec. 11, 2015, will be a major step in transforming India into an economic powerhouse with Japan's help in building bullet trains, "smart cities" and accessing nuclear technology. India and Japan are set to sign a $15 billion agreement for a high-speed train linking the Indian financial hub of Mumbai with Ahmadabad, the commercial capital of Modi's home state, Gujarat. The train would cut travel time on the 505 kilometer (315 mile) route from eight hours to two. (AP Photo/Shizuo Kambayashi, File) (AP)

The National High Speed Rail Corporation Limited (NHSRCL) on Friday awarded the ₹6,300 crore project to a contractor, who is expected to start the civil works soon. Japanese ‘Shinkansen’ bullet trains are expected to zip through the tunnel at speeds of 300-350 kmph. It will be a single tube tunnel accommodating twin tracks for travel in both directions.

“The financial bids of two technically qualified bidders were opened today and M/s Afcons Infrastructure Limited have quoted lowest bid,” said an official from NHSRCL on Tuesday. The technical bids of this tender were opened on February 9, 2023.

“As a part of the works, 39 equipment rooms at 37 locations will also be constructed adjoining the tunnel. Tunnel boring machines (TBM) with a cutter-head of 13.1m diameter will be used. Usually 5-6m diameter cutter-heads are used for urban metro tunnels,” said an engineer from NHSRCL.

Three TBMs will be used to dig about 16 kms of the tunnel and the remaining five kilometers will be through New Austrian Tunnelling Method (NATM). The channel will be 25 to 65 meters deep, with a single deepest construction point 114 meters below Parsik Hills in Thane.

Three shafts at BKC, Vikhroli and Sawli, at approximate depths of 36, 56 and 39 meters respectively, will facilitate the construction. Recently, land belonging to Godrej in Vikhroli was handed over for this project. These shafts serve as entry points for the TBMs to start boring.

Incidentally, earlier this week, the authorities had called for tenders to cut trees at Vikhroli for the tunneling purpose.

“More than 67% of total trees are invasive non-native (exotic) type generally used in livestock feed. We will undertake compensatory plantation of more than 5,300 trees. We will also transplant 141 trees,” said an official from NHSRCL.

According to NHSRCL, totally 1,828 trees are there on an area of 3.925 hectares. Of which 1,243 trees on an area of two hectares will be affected for construction of traction and distribution substations. At least 585 trees on 1.9 hectares land will be cut for construction of tunnel shaft and ventilation building.

Meanwhile, the physical progress of 32.93% in Gujarat and 13.72% in Maharashtra has been achieved for this corridor. The delay has been attributed to land acquisition issues in Maharashtra.

Out of total 352km of elevated viaduct, approximately 257km of piling, 180km of foundation, 155km of the pier and 37km of girder launching have been completed in Gujarat and Dadra & Nagar Haveli. An expenditure of ₹38,506 crore has so far been incurred on this project, which is worth ₹1.08 lakh crore.