Mumbai Metro: 17 Tunnel Boring Machines Complete Tunnelling Of 33 Km Long Colaba - Bandra - SEEPZ Corridor

In a major achievement, Mumbai Metro Rail Corporation (MMRC) on Wednesday (30 November) completed 100 per cent tunnelling of Metro-3 corridor.

MMRC achieved its 42nd and final breakthrough on the Colaba-Bandra-SEEPZ corridor at its Mumbai Central Metro Station.

Tunnel Boring Machine (TBM) Tansa-1 completed a drive of 837 metres from Mahalaxmi Metro Station to Mumbai Central Metro Station up line in 243 days using 558 concrete rings.

“It was with great pleasure that I witnessed the final breakthrough today. Tunnelling below Mumbai’s heritage precincts, in close proximity of old dilapidated buildings, existing Metro line, Railway lines, Water body with different and sometimes difficult geological conditions has been a daunting task,” said Ashwini Bhide, MD, MMRC.

With this, the overall project progress stands at 76.6 per cent.

According to the MMRC, the average production rate of each Tunnel Boring Machines (TBMs) is five to six metres per day. Around 100 workers were engaged for each TBM machine for tunnelling on the entire stretch of Metro-3 corridor.

A total of 2,86,000 cubic metres of concrete and 29,500 MT of steel was used in tunnel segment rings.

Excavated tunnels are lined with segment rings. In total, 2.8 lakh segment rings were manufactured for the entire project.

Underground metro line for Mumbai

The 33.5-km long Metro-3 corridor running along Colaba-Bandra-SEEPZ is the first underground metro corridor of Mumbai.

It consists of 27 metro stations out of which 26 will be underground and one at grade.

The first section of the Mumbai Metro Line-3 between Aarey Colony and Bandra-Kurla Complex (BKC) will be operational by December 2023.

And the second phase between BKC and Colaba would take another six months and may be completed by mid-2024.

This metro line will provide, for the first time, connectivity to the airport, Nariman Point, Cuffe Parade, Kalbadevi, Worli, BKC, Airport, SEEPZ and MIDC.

Also, two crucial heritage stations in Mumbai — CSTM and Churchgate — will also be connected through the alignment.

The project deployed 17 TBMs in 7 civil contracts to carry out 55 km of tunnels of 5.8m finished diameter.

The first TBM Krishna arrived in September 2017 at Naya Nagar of Package 4 and the first breakthrough was achieved by TBM Wainganga-1 of package 7 at Mumbai airport terminal 2.

Track installation work is progressing swiftly on this line with almost half of the stretch (455.6 per cent) completing the track laying work.

The trial run for Metro-3 began on 30 August on a three km stretch between Sariput Nagar and Marol Naka Metro Station.

Originally, the line's construction was scheduled to be completed in 2021. However, work delays caused the deadline to be missed, and the project cost increased from Rs 23,136 crore to Rs 38,000 crore.