Under one of the biggest green recreational open spaces in Mumbai, the coastline at the southernmost tip of the financial capital is changing at the speed of 3 metres per day. The country’s biggest Tunnel Boring Machine (TBM)- Mavala has been at work for almost a month, 20 metres under Priyadarshini Park at Nepean Sea Road, according to an IE report. From there, the TBM is burrowing metre-by-metre under Malabar Hill, towards its main challenge, an undersea portion aligned to Marine Drive, as part of the Mumbai Coastal Road project, worth Rs 12,721 crore. The project, comprising a road, a tunnel as well as an interchange, aims to link South Mumbai to the end of Worli, of the Worli-Bandra Sea Link through a high-speed corridor.
India’s first undersea tunnel is actually a twin tunnels’ set, one for each traffic carriageway. The length of the tunnel is 2.07 kilometre from Priyadarshi Park to Chhoti Chowpatty at Marine Drive, near Chowpatty beach at Girgaum. Starting from January 11, when Maharashtra CM Uddhav Thackeray inaugurated Mavala, the TBM has drilled 30 metres of the tunnel deep under the city’s most expensive real estate so far. With a diameter of 12.19 metres, the TBM is said to be the biggest machine of its kind in India. It is 80 metres long and weighs 2,300 tonnes. Still, nearly 50 metres of the TBM is in the launching shaft where the staff of Larsen & Toubro, engineers and labourers are at work. According to officials at the site, the TBM would have burrowed enough in another fortnight to disappear into the tunnel which it is drilling.
According to the report, Priyadarshini Park was set up on reclaimed land, and the park’s 80-100 metres falls in the intertidal sea area. The tunnel will meet the sea on Malabar Hill’s other side, at Walkeshwar. From there, the tunnel will hug Marine Drive for around half a km under the sea, before opening to a connecting road overland, 4 kilometres to Nariman Point. At the end of Priyadarshini Park, the tunnel will link to a road to Haji Ali.
With this project, the coastline in South Mumbai is set to change. The road will extend the coast inside the sea up to 100 metres length. It has been planned by the BMC that 111 hectares will be reclaimed, which is 12 times the size of Oval Maidan at Churchgate. The civic body has completed about 80 hectares out of the 111-hectare land reclamation needed for the project.
According to officials at the site, the TBM can daily drill up to 10 metres, and it is currently boring the southbound traffic tunnel. To complete drilling for one tunnel, it will take about nine months. At Chhoti Chowpatty, the TBM will be removed and for boring the northbound traffic tunnel, it will be transported back to Priyadarshini Park. It will take about two years to complete the entire process of tunneling, said Vishal Thombare, Executive Engineer with the Coastal Road department.
The report further said that a huge Slurry Treatment Plant has been set up near the launching shaft of the TBM. The Slurry Treatment Plant separates the soil, stones and water round the clock. At the construction site, diggers, dumpers and cranes are at work continuously, handling material for reclamation as well as construction. Several workers, mostly migrants from the states of Odisha and Andhra Pradesh, are working in two shifts. Work is likely to be over in July 2023. However, officials hope to complete the work sooner, given there are no hurdles like land acquisition or shifting of people.
Ashwini Bhide, Additional Municipal Commissioner, was quoted in the report saying that they need seamless connectivity from the city’s southern tip to the northern side. In terms of time, there would be an almost 70% reduction with this road. According to her, one will be able to reach from Princess Street flyover to Worli in just 10 to 12 minutes with 35% saving on consumption of fuel to cover over 10 kilometres. She further said that the project will add more open spaces as well as continuous promenade from Priyadarshini Park to Worli. Till now, 22% of physical work has been finished, and most of the work was done in the last six-seven months after the court stay was vacated, she added.