L&T’s 1st TBM S-1410A for Kolkata Metro’s Line-3 Passes Factory Tests

Tunnel boring machine (TBM) manufacturer Herrenknecht AG in Alinjivakkam, Tamil Nadu last week completed factory acceptance tests (FAT) on TBM S-1410A for 15.215 km Kolkata Metro Line-3 (Purple Line) which will connect Joka – Esplanade via 12 stations.

This Ø6.6m earth pressure balance (EPB) machine will be deployed by Larsen & Toubro (L&T) alongside another new machine (S-1411A, I’m assuming) to build twin tunnels on Line-3’s 5.05 km underground package UG1 between Mominpur – Esplanade.

This section with twin tunnels will consist of 4 underground stations at Kidderpore, Victoria Memorial, Park Street and Esplanade. At Esplanade, Line-3 when opened will form city’s first 3 line interchange with Line-1/Blue Line (Dakshineswar – Kavi Subhash) and 16.34 km Line-2/Green Line (Howrah Maidan – Sector V).

L&T was awarded 5.05 km Package UG1’s Rs. 2447 crore civil construction contract by Rail Vikas Nigam Ltd (RVNL) after being declared as its lowest bidder in June 2023. Yuksel Proje – Tumas JV has been engaged by RVNL as the project’s General Consultant (GC) since 2021.

Out of 5.05 km (chainage 9063.00m to 14113.00m), roughly 500 meters on the line’s northern-end between Esplanade and Park Street will be built using the cut and cover method.

L&T had officially commenced construction work on this package in May 2024 starting from the Victoria Memorial Station site in Maidan.

In July 2024, L&T started casting tunnel ring segments in Sarkarpool neighborhood of Maheshtala near Line-3’s Majerhat Station. From back of the hand calculations, I estimate they’ll churn out at least 4000 segments to feed the TBMs and build this section’s twin tunnels which will have an inner diameter of 5.8 meters.

Metro Rail Kolkata in July 2024 had indirectly confirmed that L&T will be deploying two Herrenknecht tunnel boring machines (TBMs), so this supplier contract shouldn’t come as a surprise.

Both machines will be launched from a TBM launch shaft located at St. Thomas School in Kidderpore neighborhood (view satellite imagery on Google Maps) and travel northward towards Victoria.

I see tunneling work starting no sooner than Q3 2025 and this underground section opening up for commercial operations no sooner than 2029.

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– TMRG