L&T’s TBM Mavala Records Breakthrough for Mumbai Coastal Road

Mavala, the largest tunnel boring machine to ever be deployed in India, today made its first breakthrough at Girgaum’s Chowpatty for Mumbai’s 29.2 km Coastal Road (Western Freeway) project.

Larsen & Toubro had commissioned this 80m long CRCHI slurry machine (DZ636) in January 2021 to build the first of two 2,070m tunnels between Priyadarshini Park Launch Ramp and Chowpatty. The machine has a cool Indian-flag themed cutterhead with a diameter of 12.19m which obviously wore off during excavation.

The TBM operated 75 meters below Malabar Hill and bored through complex geological conditions that include basalt, breccia and shale – more details can be viewed here.

The first southbound tunnel built on this section (MCRP’s 3.93 km Package-4) is 12 meters wide and consists of two lanes and one emergency lane.

Alignment of the tunnel in navy blue
Team celebrating completion of 2000m tunneling on December 29, 2021
Snap from July 2021 – via BMC

Breakthrough Video:

Back in 2021, L&T was hoping to excavate 9 meters/day and complete both tunnels by their internal deadline of June 2022 – but that just won’t be possible. The machine will now be dismantled and taken back to PDP Launch Ramp for its 2nd assignment, and I see it getting recommissioned no sooner than March-end.

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Global traveler who prefers mass rapid transit

7 Responses to "L&T’s TBM Mavala Records Breakthrough for Mumbai Coastal Road"

  1. Snowfox says:

    Tunnels are 2 lanes + 1 emergency lane each but the rest of the sections are 4 lane each wouldn’t this create bottlenecks at the tunnels?

    • TMRG says:

      I haven’t seen this project’s traffic simulation, so I’m assuming they see traffic thinning out for this section. If not, then yes will be a merging mess.

      Reminds me of NY’s west-side highway which is mostly 2 x 3/4 lanes and leads into 2 x 2 tunnels at Battery Park. Both roads serve different purposes, so no comparison.

      • Snowfox says:

        Tunnel from Coastal road directed towards Marine drive will definitely be a bottleneck during rush hours. Even Marine drive is being widened and they further plan to connect Colaba by a bridge. It is going to be a mess.

        The bridge planned towards Colaba sounds haphazardly planned. They should just reclaim the land from Nariman point to Colaba and complete the Mumbai curve.

  2. Rakesh Mathur says:

    Congrats team AECOM

  3. Kanishka says:

    TBM commissioned on 1st Tube = January 2021
    Finished Tunneling 1st Tube (breakthrough) = January 2022
    Approx. tunneling rate = (2070/365) = 5.67m/day

    “L&T hoped to excavate 9 meters/day to complete both tunnels by their internal deadline of June 2022″…not possible / wasn’t achieved.

    Now, 2nd Tube to commence tunneling = March 2022
    Expected finishing/breakthrough of 2nd Tube = March/April 2023

    Delay, wrt L&T’s internal deadline = 9 ~ 10 months…

    How’s the progress on other two packages (1 &2)?
    Pack-1: Priyadarshani Park to Baroda Palace (3.82 km) / L&T
    Pack-2: Baroda Palace near Haji Ali to the Worli end of Bandra Worli Sea Link (2.23 km) / HCC

    On track to complete by the project deadline of July 2023? If not, how much delay expected?…


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