J Kumar’s Mumbai Metro TBM Dhruv Records Final Breakthrough for Line-7A

J Kumar Infraprojects (JKIL) on Monday celebrated tunnel boring machine (TBM) Dhruv’s first and only breakthrough at the Airport Colony Shaft for Mumbai Metro Red Line’s 3.17 km Line-7A connecting Gundavali – Chhatrapati Shivaji Maharaj International Airport (CSMIA).

TBM Dhruv (T60) of Package CA-48 is a Ø6.68m dual-mode Terratec machine that was previously deployed in 2018-2021 by J Kumar – CRTG JV on Mumbai Metro Line-3 (Aqua Line)’s 4.94 km Package UGC-05 (Dharavi Station – CSMIA T1) and 4.45 km Package UGC-06 (CSMIA T1 – Marol Naka).

The machine’s parts were extensively refurbished at J Kumar’s yard on Ghodbunder Road (view on Google Maps). It began tunneling works from CSMIA’s Terminal 2 Station’s shaft in November 2023 from where it built a roughly 1.65 km tunnel for the up-line in 19 months towards Airport Colony Ramp.

Along the way, TBM Dhruv passed passed above Line-3’s twin tunnels and beneath the Sahar Elevated Access Road (SEAR) and critical utilities.

Mumbai Metropolitan Region Development Authority (MMRDA) had awarded J Kumar Infraprojects with Package CA-48’s Rs. 1,998 crore contract in September 2019.

J Kumar’s scope of work, besides the 11.38 km elevated Line-9 extension, includes building Line-7A’s viaduct, ramp, underground tunnels and 2 stations at Airport Colony and CSIA Terminal 2 where it’ll meet operational Line-3 (Aqua Line), and in the future Line-8 (Gold Line) linking to Navi Mumbai International Airport.

TBM T62 (Disha) working on the parallel down-line had arrived at the same shaft in April 2025, and Dhruv’s arrival marks the completion of Line-7A’s main-line tunneling works with only the completion of cross-passages left.

At this time I see Line-7A becoming operational no sooner than Q3 2027 looking at the standard system installation and station development work required to make a line operational in Mumbai.

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– TMRG