[Pics] Inside Mumbai Metro Line-3’s Sahar Crossover NATM Tunnels

Just east of the Sahar Road Station on the 33.5 km under construction Mumbai Metro Line-3 (Aqua Line) lies the Sahar “Scissor” Crossover Cavern – a facility for the line’s Alstom trains to switch tracks between the up-line and down-line.

The 227m long crossover was designed by Geoconsult and is 18m wide at its widest point. The cavern is being built using the New Austrian Tunnelling Method (NATM) by a joint venture of experts from Endacom, Bedi Consulting UK and Normet Group as part of a subcontract from J Kumar – CRTG JV whose responsible for building the 4.45 km package UGC-06 (CSIA T1 – Sahar Road – CSIA T2) of the line.

The JV opted for a shotcrete final lining support method, instead of a traditional fiber-reinforced plastic lined cavern. Per Endacom, this was the first time in Indian metro history that this support method has been used.

Diagram of Sahar Crossover (view large) – credit: Mumbai Metro Rail Corporation

A major milestone of this NATM cavern was achieved in February 2020 when an excavator-mounted cutter boom machine broke through from the up-line to the down-line:

NATM breakthrough – Photo Copyright: Vinay / Endacom

Here are some images shot at different times over the past few months shared by follower Vinay –

Dismantled tunnel rings built earlier by one of J Kumar – CRTG’s Terratec TBMs

When excavation works come to an end at Sahar, this NATM cavern’s tunnels will be finished with a waterproofing membrane (like this at Marol Naka) and a steel fiber reinforced cast concrete final lining.

Here’s a nice short & sharp video on NATM tunneling –

Besides 91 cross-passages, Mumbai Metro’s Line-3 has major NATM tunnels being built throughout its course at places like Cuffe Parade, Hutatma Chowk, Kalbadevi, Girgaon, Grant Road, Santacruz, Sitladevi and Marol Naka. As they near completion, I might post separately about them.

December 18 Update: Excavation is complete – see details here

For more updates, check out the Mumbai section of The Metro Rail Guy!

– TMRG

written by

Global traveler who prefers mass rapid transit

5 Responses to "[Pics] Inside Mumbai Metro Line-3’s Sahar Crossover NATM Tunnels"

  1. Samarth Kerur says:

    We are the proud team for India’s First TBM Bored Tunnel Crossover construction at Sahar, Mumbai.. Thanks for posting.

    Reply
  2. Prathap says:

    The Detail Design Consultants for this NATM Crossover is Geoconsult, they’re the one who planned complete excavation and sequence and all the primary support systems including cast insitu permanent lining, only the final lining design using sprayed concrete was prepared by Bedi.

    Reply
  3. Milind Jadhav says:

    Great work guys .
    I have completed Masters in Geology , i m looking forward for such Job oppurtunities.
    Please let me know if there is opening for any post
    Name – Milind Jadhav
    Email id – [email protected]
    Phone no.- 9768943847

    Reply

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