Thane – Borivali Tunnel Project’s 1st TBM S-1400A Passes Factory Tests

The first mega tunnel boring machine (TBM) for Mumbai’s 11.84 km Thane – Borivali twin tunnel project passed factory acceptance tests (FAT) this week at Herrenknecht’s facility in Alinjivakkam, Tamil Nadu.

TBM S-1400A is Herrenknecht’s 1st of 4 single shield hard-rock TBMs which will be deployed by Megha Engineering & Infrastructures Ltd. (MEIL) to construct twin 10.8 km road tunnels under Sanjay Gandhi National Park (SGNP) for Mumbai Metropolitan Region Development Authority (MMRDA).

The tunnels with 3 lanes each will have a maximum depth of 23m below the surface, and connect Magathane’s Ekta Nagar in Borivali with Tikuji-Ni-Wadi at Manpada in Thane. Cross-passages will be constructed every 300 meters connecting both tunnels to aid in evacuation and maintenance.

S-1400A and the other three TBMs will have a 13.2m diameter cutterhead, which is bigger than the Mumbai Coastal Road Project‘s 12.19m diameter CRCHI slurry TBM Mavala (DZ636) that built two tunnels between 2021-2023.

They will however be slightly smaller than the Mumbai – Ahmedabad High Speed Rail‘s two 13.56m diameters TBMs. The first machine, S-1392, had passed FAT in August 2024, but I hear it’s still stuck in China due to ongoing export restrictions. So until they get freed up and get to work, S-1400A and its sister machines for a short while will be the largest diameter TBMs to get deployed in India.

MEIL is executing the Thane – Borivali Tunnel project under a 4 year deadline after being declared as the preferred bidder for the project’s 2 civil construction contracts in May 2023.

At this time I see tunneling works beginning no sooner than Q1 2026. The project aims to drastically reduce the driving time between both spots from 1-2 hours (depending on day/time) to just about 15 minutes.

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– TMRG