Twenty of the total 52 km of tunnelling for the city’s underground Metro 3 (Colaba-Bandra-Seepz) has been completed, Mumbai Metro Rail Corporation Limited (MMRCL) officials said on Wednesday, while announcing that overall, 38 % work of the project is now over.
The announcement came as the project achieved its fifth milestone, when one of the tunnel boring machines (TBM) deployed achieved a breakthrough at Chhatrapati Shivaji Maharaj International Airport (CSMIA) T-2 Metro station. The TBM is a highly-mechanised earth pressure balance (EPB) device that will be used around 20-25 m below the ground to construct tunnels with a circular cross-section.
Commissioned last April, the TBM, named Wainganga 3 that began boring from Pali ground, completed its tunnelling drive of 1.31 km in a section of the project categorised as Package 7, to see light at T2 station. A statement by MMRCL said that a team of nearly 150 engineers, technicians and workers are working on the Metro 3 line, which is a 33.5-km corridor.
A senior MMRCL official said that Wainganga 3 drilled its way through rocky strata made of basalt and volcanic breccia, working for 318 days to attain the breakthrough. This particular portion passes below Mumbai Metro Line 1 station at Marol Naka and Sahar Elevated Road, on its way to T-2. The 92-m long Wainganga 3 bored, on an average, 4.2 m daily, shaping the tunnel with 937 RCC cement rings. The overall tunnelling length for the Metro 3 corridor in both directions is 52 km. Wednesday’s breakthrough was the fifth on this line.
S K Gupta, Director (Projects), MMRC, said: “We have completed 38 per cent of the overall civil work. Today, it was the fifth breakthrough for the tunnel and in all, there will be a total of 32 breakthroughs for tunnelling. There are basically major milestones for us in the course of the project.”
Source: Indian Express