Per a couple of my tunneling industry connections, Herrenknecht AG has been finalized by Afcons Infrastructure to supply at least 2 tunnel boring machines (TBMs) for 20.377 km underground Package C-2 of the 508.17 km Mumbai – Ahmedabad High Speed Rail (MAHSR Bullet Train).
Afcons was awarded C-2’s Rs. 6397.27 crore contract in June by India’s National High Speed Rail Corporation Ltd. (NHSRCL) with a 1888 day (5.17 years) deadline. The scope of C-2 connects chainage Km 0.773 (Bandra Kurla Complex Station) to Km 21.150 (Shilphata Ramp).
This development shouldn’t come as a surprise as Afcons has historically tied up with Herrenknecht for metro projects across India.
NHSRCL’s tender documents had mandated the assigned contractor to deploy at least 3 machines of 13.1m diameter to bore an approximately 16 km long tunnel, but I hear Afcons will be starting out with 2 machines and order another if things start going awry.
This is reminiscent to me of their strategy in the Delhi-Meerut RapidX (RRTS) project where Afcons – driven by confidence in their tunneling expertise – deployed 3 Terratec machines (S88, S89, S90) instead of 4 mandated machines.
Afcons plans to construct 3 shafts at BKC Station, Vikhroli, and Sawli at approximate depths of 36m, 56m and 39m respectively to launch and retrieve their TBMs. An inclined shaft of 42m at Ghansoli and tunnel portal at Shilphata will facilitate 5 km of NATM tunneling works.
At 13.1m, these mega TBMs will be the largest diameter machines to ever been deployed in India – bigger than even Mumbai Coastal Road Project‘s 12.19m diameter CRCHI slurry TBM Mavala (DZ636) which just recorded its final breakthrough in May.
For comparison, the diameter of TBMs deployed for metro tunnels in India have so far ranged between 6.45m to 6.68m. Many 10m diameter machines have been deployed for water projects in Andhra Pradesh and Madhya Pradesh.
Back in June-end, Sarathy Geotech & Engineering Services through a sub-contract started geotechnical soil investigation work for this section. Given the amount of preparatory work, construction and TBM activities (manufacturing, delivery, assembly) pending – I see tunneling work starting no sooner than mid-2025.
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