Larsen & Toubro and Freight Wings on Thursday lowered the shields of TBM Mavala – the largest tunnel boring machine (TBM) to ever be deployed in India – at the Priyadarshini Park launch ramp for building twin 1,920m tunnels of Mumbai’s 29.2 km Coastal Road (Western Freeway) project.
Assembly works on it commenced in September on reclaimed land just 250 meters away from the launch ramp. Last week, Freight Wings transported three backup gantry parts (weighing 350 MT) and its newly assembled shields (weighing 1500 MT) over to the launch ramp using a 200 wheel self-propelled modular transporter.
Larsen & Toubro will deploy Mavala on the MCRP’s 3.93 km Package-4 for constructing 12m wide twin (3 + 3 lane) tunnels under Malabar Hill (75m deep) and Girgaum Chowpatty (25m deep) between Priyadarshini Park and Marine Drive in South Mumbai. Details on the expected geology can be viewed here.
Over the past week, Brihanmumbai Municipal Corporation (BMC) and Larsen & Toubro christened the TBM as Mavala (note the new stickers on the side) after the troops of Chhatrapati Shivaji who excelled in mountain warfare.
This is a break from giving female names in a long-standing tradition, dating back to the 1500s, in the mining/tunneling world to bring good luck to the project team. The last time a male name was used (TBM Chandi in Kolkata) didn’t end too well when the TBM hit an aquifer leading to heavy soil displacement which triggered the collapse of several residential buildings over a month’s period.
On Thursday, the 10 meter long assembled shields were lowered by Freight Wings into the launch ramp using a 2500 MT capacity customized Strand Jack system for this project. This system is similar, but way larger, than the one deployed by them to retrieve and lower Dogus-Soma JV’s TBMs 1238 and 1239 for Mumbai Metro’s Line-3.
An image and video of how the TBM will eventually look like with its Indian flag themed cutterhead can be viewed here.
Here’s a snap of L&T’s precast segment casting yard, shot in October, which has been setup close to the assembly site:
According to BMC, L&T will use Mavala to excavate around 3 meters/day, with a total excavation time of 276 days to complete both tunnels. Per a comment left below by Sandeep, who claims to be associated with the project, the expected excavation rate will be higher at 9 meters/day.
Stay tuned for a post on when Mavala gets commissioned!
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