Bullet train: Bids invited for 20-km underground tunnel

The bids for the tunnel work have to be submitted by March and the bullet train construction work is likely to begin by the end of next year

In what could be termed as a major development on the ambitious Mumbai-Ahmedabad bullet train corridor, the National High Speed Rail Corporation Limited (NHSRCL) on Friday invited bids for the construction of the 20.37-km underground tunnel, including a 7-km part under the sea between Bandra-Kurla Complex (BKC) and Shilphata in Thane, for the route. The bids for the tunnel work have to be submitted by March and the construction work is likely to begin by the end of next year.

A 7-km part of the bullet train tunnel between Bandra-Kurla Complex (BKC) and Shilphata will be under the sea. (HT FILE)

The underground tunnel will be a single-tube twin track of 13.1m diameter, which will start from BKC and end at Shilphata. Of the 20.37km, 15.42km of tunnelling work will be carried out with three tunnel-boring machines (TBM) and the remaining 4.96km will be carried out with a new Austrian tunnelling method.

“NHSRCL has invited bids for the tunnelling work of 21km. The package is open to Japanese and Indian companies,” said a senior NHSRCL official.

In order to complete the work in the stipulated time, three shafts have been planned. The depth of the tunnel will vary from 25-40 metres. The tunnel will cross Thane creek. The survey works under the creek was conducted by underwater static refraction technique and was successfully completed.

The work on the underground sea tunnel is critical and had begun in December 2017, wherein a team of engineers from NHSRCL and Rail India Technical and Economic Service Ltd, and Japan’s Kawasaki Geological Engineering studied data on the seabed, based on geo-technical surveys. The study was conducted to understand the structure and depth of the seabed of Thane Creek and based on the report the alignment of the tunnel was fixed.

The 508.17-km-long Mumbai-Ahmedabad high-speed rail corridor project work commenced in 2017. The work on the project was initially aimed to be completed by 2023. The estimated cost of the project is ₹110,000 crore, of which ₹88,000 crore will be funded by Japan International Cooperation Agency (JICA).

The project is facing hurdles owing to land acquisition issues, mostly in Maharashtra. Of the 508.17km for the project, 155.76km is in Maharashtra, 384.04km in Gujarat and 4.3km in Dadra and Nagar Haveli.

The Mumbai-Ahmedabad corridor will have stations at Bandra-Kurla Complex (terminal on Mumbai-end of the corridor), Thane, Virar, Boisor, Vapi, Billimora, Surat, Bharuch, Vadodara, Anand, Ahmedabad and Sabarmati.