Nov 16
Tunnelled Milestone
Tunnelled Milestone
THE Mumbai Coastal Road Project (Package-4) achieved a new milestone when India’s largest tunnel boring machine (TBM) Mavala completed a one km tunnelling job on 4 September. The TBM had begun operating in January in the presence of Maharashtra Chief Minister Mr Uddhav Thackeray and his minister-son Mr Aditya Thackeray. 
The 12.19 m diameter Mavala completed the first km of the over two km tunnelling beneath the heart of South Mumbai. The overburden along the alignment varied from as low as 6 m to as high as 65 m. Moving ahead, Mavala will negotiate under the surface lined with heritage buildings on the iconic Marive Drive, followed by the inter-tidal zone towards Girgaon Chowpatty beach.
L&T’s Whole-Time Director & Sr EVP – Civil Infrastructure Mr S V Desai visited the site on the occasion of the TBM milestone. Mr Iqbal Singh Chahal, Commissioner – Municipal Corporation of Greater Mumbai (MCGM) lauded the efforts of the L&T team. The tunnelling for the coastal road is a challenging job and the L&T team has been negotiating the difficulties by building on their capabilities and undertaking innovative methodologies. The challenges apart, the project has also been notching up many firsts.
  • This is the first under-sea tunnelling being carried out in the country. TBM Mavala was assembled in-house by an L&T team as the OEM experts could not reach the site because of COVID.
  • To save time, the TBM was assembled on the surface. The TBM’s components, weighing up to 1,500 MT, were lowered in a single operation using the innovative strand jack method, which is a first-of-its-kind in India. 
  • It is the heaviest TBM lowering into the shaft in one go.
  • The heaviest cutter head – 350 MT – was lowered for the first time in India, second only to the Bertha TBM used in Seattle, US. 


It was in October 2018 that MCGM awarded L&T the contract for Package-4 that begins near the Princess Street flyover at Marine Drive and stretches to Priyadarshini Park. The scope includes construction of the 2-km-long twin-bored tunnel along with cut and cover, ramp, etc., forming a combined road length of 4 km. When completed, it will be the largest and deepest bored road tunnel in India. The works include reclamation and other associated operations at Priyadarshini Park, with construction of a new promenade along the new coastal road.


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