Metro-3 cuts its pathtowards smoother travelTunneling of two Metro-3 stations to be completed by Dec 12

The Mumbai Metro Rail Corporation (MMRC) is set to complete 100% tunnelling work between Marol Naka and Seepz — as part of the 33.5-km Metro-3 corridor — by December

The Mumbai Metro Rail Corporation (MMRC) is set to complete 100% tunnelling work between Marol Naka and Seepz — as part of the 33.5-km Metro-3 corridor — by December 12. Around 2,500 workers and more than 350 equipment are at work on the 7.09-km Marol Naka-Seepz stretch, which will be the first of the seven packages of the underground Metro corridor to be completed.

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MMRC, which is executing the Colaba-Bandra-Seepz line, has completed 70% of the tunnelling on the entire stretch with 23 tunnel breakthroughs. The 24th tunnel breakthrough is expected next week at Seepz.

The corridor, which has been touted as one of the most challenging projects ever, is being executed by 16,000 people

When HT visited two underground stations on the Marol Naka-Seepz stretch (package number 7) — the Marol Naka station and the Maharashtra Industrial Development Corporation (MIDC) station — it found that 800 cubic meters of concrete was being used to create slabs.

At Marol Naka, the Metro-3 corridor will be running beneath the elevated Metro-1 (Versova-Andheri-Ghatkopar) corridor. With pillars of Metro-1 coming in the way of Metro-3’s alignment, MMRC is constructing two station boxes on either side of the former. “These two boxes will be connected via 12 cross passages for passengers at the platform level,” said a site engineer at Marol Naka.

MMRC is making use of both tunnel boring machines (TBM) and the New Austrian Tunnelling Method (NATM) for tunnelling at Marol Naka station. NATM, a more conventional method in which breakers and boomers are used for tunnelling, is said to be commonly used in denser cities like Mumbai. At Marol Naka station, NATM is being used to widen the tunnels and create space for platforms. The station, which is 25m below ground level and 256m in length, will have eight entry-exit points. SK Gupta, director (projects), MMRC said, “Marol Naka station is planned on the junction of the congested Andheri-Kurla roads. It also crosses the existing Metro-1 and is close to many buildings. Construction of the tunnel and station in these circumstances is a big challenge. To meet these requirements we decided to use a combination of NATM and cut-and-cover method for construction of the station.”

The MIDC station, which is 21m below ground level, will provide much-needed connectivity to the isolated industrial area. The station’s structure appeared to be more complete than Marol Naka station. A site engineer at MIDC said, “We have completed 78% of the concourse slab and 58% of the roof slab. In fact, we have also started construction of boxes for the control room and signalling system at the concourse level.” The MIDC station is 240m in length with four entry-exits points.

While the state has put a stay on the construction of the Metro-3 car shed in Aarey, all seven packages of the corridor have completed more than 50% tunnelling. Once operational, Metro-3 is expected to cater to 17 lakh passengers, reducing an estimated 6.5 lakh car trips every day.