Mumbai Coastal Road Project: The Significance Of Second Tunnel Breakthrough

Amit Mishra

May 31, 2023, 12:05 PM | Updated 12:18 PM IST

Mumbai's coastal road under construction. (@AshwiniBhide/Twitter)
Mumbai's coastal road under construction. (@AshwiniBhide/Twitter)

The under-construction Mumbai Coastal Road Project (MCRP) crossed another milestone Wednesday (30 May) when the breakthrough of the second and final undersea tunnel was achieved at Priyadarshini Park (PDP) near Breach Candy.

Breakthrough of final  tunnel of MRCP
Breakthrough of final tunnel of MRCP

The 10.58-km-long MCRP by the Brihanmumbai Municipal Corporation (BMC) will connect Nariman Point in South Mumbai with the Bandra-Worli Sea Link (BWSL) at Worli through a series of roads and underground tunnels.

Mumbai Coastal Road Project Alignment (BMC)
Mumbai Coastal Road Project Alignment (BMC)

The high point of this project is the twin tunnels beneath the Arabian Sea near Girgaon Chowpatty, making it India's first undersea tunnel.

The 2.07-kilometer twin tunnel system runs from Priyadarshi Park to Chhoti Chowpatty at Marine Drive, close to the landmark Chowpatty beach at Girgaum.

TBM Mavala

The twin tunnels have been excavated using a Chinese Tunnel Boring Machine (TBM), Mavala, named after Chhatrapati Shivaji Maharaj’s Mountain warfare experts.

The TBM Mavala, with a diameter of 12.19 metres, is the largest tunnel boring machine to ever be deployed in India and has been manufactured by China Railway Construction Heavy Industry Co. Ltd. (CRCHI).

TBM Mavala tunneling for Mumbai Coastal Road project (@AshwiniBhide/Twitter)
TBM Mavala tunneling for Mumbai Coastal Road project (@AshwiniBhide/Twitter)

It was in December 2020, when the Larsen & Toubro commenced the deployment of 2,500 tonne TBM Mavala at the Priyadarshini Park launch ramp for building twin tunnels of the coastal road project.

The BMC initiated the digging of the first tunnel in January 2021 from Priyadarshini Park (PDP) end, and the breakthrough of the first tunnel was achieved on 11 January 2022 at the Chowpatty end.

Subsequently, on 26 April 2022, the TBM was pushed leftwards, towards the side of the north-bound tunnel, by using a hydraulic-jack powered turn-table which helped in rotating the TBM by 180 degrees.

The final breakthrough was carried out on 31 May out in the presence of Chief Minister Eknath Shinde and Deputy Chief Minister Devendra Fadnavis.

Earlier in August 2022, the TBM Mavala created a history by excavating 456.72 metre length in a month - it broke the previous global record of 455.4 metre for monthly tunnelling done by a 13-metre single shield EPB (Earth Pressure Balance) TBM.

November Opening

The completion of the twin tunnels in the Mumbai Coastal Road Project marks an important milestone. Overall, 75 per cent of the total project has been completed, and the remaining works are fast approaching completion.

This milestone is a major leap for the civic body, which is aiming to open the coastal road for public usage by November 2023.

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