Mumbai Metro’s TBM Surya-2 Records Breakthrough at Hutatma Chowk

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On Friday, Tunnel Boring Machine Surya-2 operated by the Larsen & Toubro – Shanghai Tunnel Engineering Company (L&T – STEC) JV made a breakthrough at Hutatma Chowk Station’s northern-end on Mumbai Metro’s 33.5 km Aqua Line (Line-3).

This was Surya-2’s third (and penultimate) breakthrough, 4.25 km Package UGC-01’s 5th of now 8 (earlier 7) planned breakthroughs for the Cuffe Parade – CST section, and overall Line-3’s 33rd of what will now be 42 (earlier 41) planned breakthroughs.

This Robbins Crossover XRE tunnel boring machine (TBM) with a 6.65 meter diameter was originally launched from Cuffe Parade to build Line-3’s down-line tunnel, and recorded breakthroughs at Vidhan Sabha Station in May 2019 and Churchgate Station in October 2019.

For its last assignment that ended today – the machine was recommissioned from Churchgate in January 2020 and took 275 days to travel 653 meters while building 502 rings to arrive at Hutatma Chowk.

Interestingly, the breakthrough took place at the NATM-mined tunnel on the down-line, which was not part of the original tunneling plan as this TBM was supposed to pass through this section without recording a breakthrough. Post-tunneling, the plan was to dismantle the tunnel rings during NATM excavation. But it appears that in the interest of time, NATM work to house the station’s down-line tunnel and platform took precedence.

Surprisingly, Mumbai Metro Rail Corporation’s recent press release on October 7 also indicates the TBM should have passed through – see row #5 indicating Churchgate to CSMT (downline, 1233 m), so it appears there’s a disconnect between their communications/social media and the civil-works teams as this change in plans (to switch tunneling and NATM works around) must have taken place many moons ago.

Package UGC-01: Cuffe Parade – CST – view Mumbai Metro Aqua Line info & route map
Hutatma Chowk Station’s NATM-mined down-line tunnel (left) and cut & cover station box for the up-line tunnel (right)

More on details on the unique Hutatma Chowk Station can be viewed here.

Photo Copyright: MMRC
Future down-line platform area – Photo Copyright: MMRC
L&T-STEC’s engineers – Photo Copyright: Abhijeet Tripathi
L&T STEC’s safety officers – Photo Copyright: Neetesh Prajapati

TBM Surya-1 working on the parallel up-line was commissioned barely a week after Surya-2, so that should also make its breakthrough at Hutatma Chowk’s cut and cover box soon.

Here’s a status of package UGC-01 between Cuffe Parade and CST stations where 3 breakthroughs are still pending. This table is best viewed on a desktop device –

TBM Line From To Distance Status
1 Up Cuffe Parade Vidhan Bhavan 1128m Completed
1 Up Vidhan Bhavan Churchgate 498m Completed
1 Up Churchgate Hutatma Chowk 649m In Progress
1 Up Hutatma Chowk CST 551m Yet to Begin
2 Down Cuffe Parade Vidhan Bhavan 1254m Completed
2 Down Vidhan Bhavan Churchgate 481m Completed
2 Down Churchgate Hutatma Chowk 653m Completed (this post!)
2 Down Hutatma Chowk CST 556m Yet to Begin

With 33 breakthroughs completed, including this one with a change in plans, there are now 9 more breakthroughs pending on Mumbai Metro’s Line-3:

Package Section Distance, Status
UGC-01 Churchgate – Hutatma Chowk (up-line) 650m, In Progress
UGC-01 Hutatma Chowk – CST (up-line) 551m, Not Started
UGC-01 Hutatma Chowk – CST (down-line) 556m, Not Started
UGC-03 Science Museum – Mahalaxmi (up-line) 1118m, Not Started
UGC-03 Mahalaxmi – Mumbai Central (up-line) 837m, Not Started
UGC-03 Science Museum – Mahalaxmi (down-line) 1136m, In Progress
UGC-03 Mahalaxmi – Mumbai Central (down-line) 830m, Not Started
UGC-04 Siddhivinayak – Dadar (down-line) 1126m, In Progress
UGC-06 Sahar Road – CSIA T1 (up-line) 1516m, In Progress

For more updates, check out the Mumbai section of The Metro Rail Guy!

– TMRG





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