TBM S710 Makes a Breakthrough at Chennai Metro’s Central Station

A little more than four years after being commissioned from Washermenpet in north Chennai, Tunnel Boring Machine S710 finally made its 3rd and final breakthrough for Chennai Metro’s package UAA-01 on Friday afternoon at the Central Station. The Herrenknecht EPB TBM, operated by the Afcons-Transtonnelstroy JV, was last commissioned from the High Court Station in August 2014 (after a breakthrough there in March) and traveled roughly 1.3 km while building 928 rings along the way for the 32.10 km Wimco Nagar – Airport line.

This TBM, like its sister machine TBM S711, encountered mixed face hard rock conditions as they passed in the vicinity of several historic buildings with weak foundations. As such, tunneling had come to a stand-still in early 2016 and it became impossible to operate both TBMs at the same time. In July 2016, TBM S710 restarted mining after S711 was far ahead and out of its influence zone.

This breakthrough marks the completion of tunneling works on package UAA-01 (Egmore & May Day Park – Washermenpet), was the 6th to be recorded at the Central Station and overall the 38th of 40 breakthroughs in Chennai. The first breakthrough at Central was achieved in July 2014, 2nd in January 2016, 3rd in October 2016, 4th in November 2016 and 5th in December 2016.


High Court to Central stretch – view Chennai Metro map & info

Red: UAA01 ; Blue: UAA02; Green: UAA03

Red: package UAA01 (now complete!)

D-wall – Photo Copyright: Gyanendra Singh

Photo Copyright: Daily Thanti

Photo Copyright: Gyanendra Singh

Photo Copyright: Deepak Bora Dungar

Photo Copyright: Karthick

Afcons’ safety team – Photo Copyright: Gyanendra Singh

Afcons’ workers and engineers – Photo Copyright: Deepak Bora Dungar

Afcons’ tunneling consultants and experts – Photo Copyright: Deccan Chronicle

Central Station:

Photo Copyright: Karthick

Photo Copyright: Karthick

Photo Copyright: Karthick

Photo Copyright: Karthick

Photo Copyright: Karthick

TBM S710 can be seen in the back – Photo Copyright: Karthick

Photo Copyright: Daily Thanti

Breakthrough Videos:

There are now just 2 more TBM breakthroughs left on package UAA-02 (May Day Park – AG-DMS; shown in green in the map at the top of this post) for all tunneling works to end on Chennai Metro’s 45.1 km Phase 1 project. Here’s their progress as of February 10 (each ring = 1.4m)

TBM Origin Destination Rings Built/Total
S703 Thousand Lights AG-DMS 380/1248
S704 Thousand Lights AG-DMS 235/1246

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


written by

Global traveler who prefers mass rapid transit

8 Responses to "TBM S710 Makes a Breakthrough at Chennai Metro’s Central Station"

  1. Anand says:

    Hi TMRG

    Gr8 news to know that all 6 breakthroughs are achieved @Central Metro.
    What’s the realistic forecast now for S703 and S704 to complete their operations?
    Also when we can expect Central Metro to be opened at least Central – Mount line?

    Thanks for your continuous update in Chennai section! Keep up your good work

    • arvind says:

      There was a recent article on toi that said central to mount will be opened at the end of this year and that the anna salai stretch would be opened by mid next year. Given cmrls actual vs estimated gap of about a month or two (in airport to little mount they said august but was only opened in mid September) probably we can expect a beginning 2018 and a sep 2018 opening for central to mount and anna salai respectively.

      However cmrls says koyambedu to nehru nagar will open around june and nehru nagar to egmore will open im Oct sometime.

    • TMRG says:

      Hi, thanks for your message of appreciation!

      1) S703 and S704 – tough to estimate. Afcons is experiencing nice advancement rates right now, but you never know what can go wrong as the machines are in poor shape. As per one engineer, they’re looking at an August-September breakthrough. I’ll post an update here when a new ring update is available.

      2) Central – Egmore stretch – I’m pretty sure they’ll open it along with the Central – Washmenpet section. As Central’s 6 breakthroughs have just taken place, give it until mid to late 2018 to open. It would be great if trial runs begin by the end of this year.

      • TMRG says:

        Update – Just heard back from the contractor. Both TBMs are now struggling in the mixed ground conditions

        S703 – 501/1248
        S704 – 310/1246

  2. Saurabh says:

    That was 1 mighty BIG SPLASH shown in the 1st video. Congrats to everyone involved 🙂

  3. RAKESH SHARMA says:



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