Mumbai TBM to start coastal road work next month

10 September 2020

Brihanmumbai Municipal Corporation (BMC) is set to begin tunnel boring on the Mumbai Coastal Road Project, India, by October 25, reported The Hindustan Times. The 3.4km-long twin tunnels form part of the Coastal Road between Priyadarshini Park at Malabar Hill and Girgaum Chowpatty.

The TBM operation is envisaged will take between eight to ten months to complete both tubes which run through a difficult geology comprising mainly basalt of 200MPa maximum compressive strength. The 12m-diameter tunnels will have three traffic lanes and will lie at depths of between 25-70m below ground. A section of the alignment between Girgaum and Malabar Hill will run under the sea.

Launch and reception shafts at both ends of the parallel tubes have been completed. Having arrived on site in April in 17 truckloads, the TBM is currently being partially assembled above ground after which it will be lowered for the completion of the final assembly stages underground.

The Chinese-made CRCHI machine is expected to take around four to five months to excavate each tube, starting from Priyadarshini Park, boring the length of one tube, then pulled out at Girgaum Chowpatty to be taken back to Priyadashini Park to start the second tube. BMC estimates that the TBM will bore around 3m/day, with a total excavation time of 276 days to complete the tunnels’ excavation.

So far around 16% of the Coastal Road Project has been completed; full completion is expected to take place by July 2023.