Underground Metro in Mumbai gets its first tunnel digger
The Tunnel Boring Machine, which is imported from China, will be assembled in the next 45 days and then deployed from a Mahim launching shaftUpdated: Sep 07, 2017 01:00 IST
The Mumbai Metro Rail Corporation has received the first Tunnel Boring Machine (TBM) that would be used to drill twin tunnels for the 33.5km Colaba-Bandra-SEEPZ Metro-3 line. Sixteen more highly-mechanised TBMs will arrive in the city in the period of next two years to drill 51km of tunnels.
Procured from German major Herrenknecht AG, from its manufacturing facility in Guangzhou, China, the TBM will be lowered from launching shaft in Naya Nagar, Mahim using cranes with heavy gantry of capacity of 135 tonnes.
According to MMRC, the TBM will be assembled in the next 45 days and then deployed for construction of 6.08-km twin tunnels between Siddhivinayak and Dharavi. The tunnelling is expected to start in October. The Earth Pressure Balance (EPB) device will be used to construct tunnels in circular cross section some 20 meters to 25 meters below the surface.
“With the arrival of our first TBM, we have kicked off our tunnelling activity, which is another most critical part of this project. In a period of next two years’ total of 17 TBMs will be deployed for constructing the 33.5 km twin tunnels” said Ashwini Bhide, Managing Director, MMRC.
The TBM operator will sit in an air-conditioned cubicle within the machine. The TBMs are reportedly self-sufficient with a toilet and has its own sanitation system.
According to S K Gupta, Director (projects), MMRC, the TBMs that will come to Mumbai are similar machines that are used worldwide for boring. “Barring a few technical changes that are done based on the geology of the areas, these machines are same or similar to what we see around the world,” Gupta said.
He added that the tunnelling will start by October-end at the Naya Nagar shaft. The TBM will drive through Shitaladevi Metro Station and will be retrieved at the proposed Dadar Metro station. Similarly, a second TBM will be launched from the same shaft for second twin tunnel by November-end. The total length of this tunnel drive is 2.5 km for each tunnel. The TBM will take about 1 year to complete this drive.