Mumbai Coastal Road Project: India's First-Ever Undersea Twin Tunnels Near Completion, Set To Open In November

India's first undersea twin tunnels in South Mumbai are almost finished and are all set to open by November.

It is part of the Rs 12,721 crore Mumbai Coastal Road Project (MCRP), which is nearing completion.  

Starting near Girgaon and ending at Breach Candy’s Priyadarshini Park, the tunnels go under the Arabian Sea, Girgaon Chowpatty and Malabar Hill.

Constructed with a diameter of 12.19 metres and located 17-20 metres below sea level, the tunnels span almost one kilometre beneath the sea, reaching a maximum depth of 72 metres at Malabar Hill.

The Brihanmumbai Municipal Corporation (BMC) is responsible for building this project.

According to Ashwini Bhide, MD of Mumbai Metro Corporation, 93 per cent of the tunnel work is finished.

The tunnel will have two passages for motorists and four for pedestrians. It consists of three lanes, each measuring 3.2 metres.

According to Namkak Cho, a senior engineer, two lanes in each tunnel will be running while the third will be reserved for emergencies or in cases of high vehicular density.

Mumbai Coastal Road Project

The project is to be constructed in two phases. The second phase involves connecting Bandra Sea Link to Kandivali Junction. Work on this stretch is yet to commence.

Once completed, the ambitious coastal road project (phase 1) will add an 8.5 km long and 20-metre-wide sea promenade to the city between Priyadarshini Park at Napean Sea Road and the Worli side of the Bandra Worli Sea Link. 

While Larsen and Toubro is executing Package 1 and 4 of the coastal road at Rs 7,489 crore, a joint venture between Hindustan Construction Company (HCC) and Hyundai Development Company (45 per cent) is executing Package 2 and 3 at the cost of Rs 2,126 crore.

The coastal road has three interchanges: Haji Ali, Worli, and Amarson's junction.

According to the MCRP chief engineer, Mantayya Swami, the coastal road would cut down noise and air pollution while reducing the journey time between Marine Lines in south Mumbai and Kandivli in north Mumbai by 70 per cent and fuel consumption by 34 per cent.

India's Largest Tunnel-Boring Machine - Mavala

One of the key features of India's latest project is the implementation of the largest tunnel-boring machine in the country's history.

TBM Mavala completed the first tunnelling work on 11 January 2022. It began the excavation work for the second tunnel on 30 March. Mavala excavated around 600 metres of the second tunnel within three months.

Swami explained that the TBM has three primary sections: a cutter head with high-powered spokes, a seal that collects sediments and rocks, and a control room located in Mavala, where the operation is entirely managed.