Mumbai to get largest tunnel boring machine for coastal road work

The city is set to receive its largest tunnel boring machine from China in February to work on part of the Brihanmumbai Municipal Corporation’s (BMC) coastal road project.

The tunnel boring machine (TBM) will be 12.19 metre wide, as tall as 4.5 storeys of a building. In comparison, the ongoing Metro construction uses a 7-metre-wide TBM.

The TBM will drill the 3.4-kilometre-long twin tunnels which will partially run under the sea, between Girgaum and Malabar Hill, as part of the 9.98-kilometre-long coastal road between Priyadarshini Park, and the Worli end of Bandra Worli sea link.

Additional municipal commissioner in charge of the coastal road project, Vijay Singhal, said, “The TBM will be imported from China and will arrive in Mumbai in February 2020. Once the machine comes, work on constructing the tunnels will start right away.”

The twin tunnels will enter the ground at Girgaum Chowpatty, go partially below the sea via Malabar Hill, to emerge at Priyadarshini Park.

The total length of each tunnel is 3.4 kilometre long counting the distance of entry and exit routes. Given there will be two 3.4-kilometre-long parallel tunnels, the total distance covered will be 6.8 kilometre.

They will run 25 metre below the surface at Girgaum, and 75 metre below the surface at Malabar Hill.

Each tunnel will be 12 metre wide and will have two traffic lanes of around 3 metre to 3.2 metre width, and an emergency lane.

The minimum life span of the structure is expected to be 100 years.

Once the TBM arrive in Mumbai, work will be completed within 276 days, barring unforeseen delays, according to a senior civic official in charge of the project.

“The TBM will be able to drill through a minimum of 3 metres a day, so to complete the entire planned length of the tunnel, we will need roughly 276 days. This is the newest technology, so the sound and vibrations felt from the boring are minimal,” said the official.

The cost of acquiring the TMB will be borne by Larson and Toubro, the contractor awarded this part of the coastal road package.