1st TBM for Mumbai – Ahmedabad Bullet Train Passes Factory Tests

August 26, 2024 Update: Two images of the TBM have been removed from my post per Herrenknecht’s request.

August 20, 2024 Original Post: Say hello to TBM S-1392! Herrenknecht AG in China has completed factory acceptance tests (FAT) for the first tunnel boring machine (TBM) of the 508.17 km Mumbai – Ahmedabad High Speed Rail (MAHSR Bullet Train) project.

This 13.56m diameter mega TBM (largest in India) will be deployed by Afcons Infrastructure on the project’s 20.377 km underground Package C-2 between Km 0.773 (Bandra Kurla Complex Station) and Km 21.150 (Shilphata Ramp). This section includes a roughly 3 km “undersea” tunnel below Thane Creek.

This mixshield machine will be commissioned in 2025 along with another machine to construct a 16 km single-tube tunnel to accommodate both up-line & down-line tracks. As shared in 2023, although NHSRCL’s tender documents mandate at least 3 machines to be deployed, I hear Afcons will be starting out with 2 machines and order another if things start going awry.

India’s National High Speed Rail Corporation Ltd. (NHSRCL) had awarded Afcons Infrastructure with underground Package C-2’s Rs. 6397.27 crore contract in June 2023 with a 1888 day (5.17 years) deadline.

Afcons is currently constructing 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.

Although S-1392 is the first TBM to get ready it’s not necessarily “TBM-1”, shown in the graphic below, which is slated to excavate from Vikhroli to BKC Station. Its exact launch location remains unknown to me.

NHSRCL’s July update shows the excavation progress made at all shafts at the start of the video:

At 13.56m, Afcons’ mega TBMs will be the largest diameter machines deployed in India – bigger than even the Mumbai Coastal Road Project‘s 12.19m diameter CRCHI slurry TBM Mavala (DZ636) which built two tunnels between 2021-2023.

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.

To getter better idea of how massive this machine is, check out Herrenknecht’s employee walking on the bottom-right corner of this snap:

S-1392 will now be dismantled and get ready for shipment. Looking at all pending activities, I see tunneling work starting no sooner than Q3 2025. Some of those activities broadly include disassembly, shipment & delivery, shaft completion, lowering & assembly, and site acceptance tests.

It remains to be seen, but most likely the second machine will be S-1393. As always, nicknames for both machines are expected to be assigned right before tunneling begins.

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– TMRG