By Pragati Saha
The Mumbai-Ahmedabad bullet train project saw major progress by connecting the 4.88 km-long tunnel between Shilphata and Ghansoli. According to the National High-Speed Rail Corporation Limited (NHSRCL), the breakthrough occurred on Saturday morning.
Union Railway Minister Ashwini Vaishnaw was in attendance during the Ghansoli shaft when this milestone took place through a controlled blast. The tunnel is part of a 21-km underground section that connects the Bandra-Kurla Complex to Shilphata, including a seven-km portion under Thane Creek. It was dug by using the New Austrian Tunnel Method.
With its recent progress, the bullet train tunnel currently joins the Savali Shaft to the tunnel portal at Shilphata, which links it with the viaduct portion of the Mumbai-Ahmedabad High Speed Rail project.
The work on this tunnel started in May 2024 in three phases, where the first milestone took place on July 9 with a continuous sector of 2.7 km. Besides, an extra intermediate tunnel was constructed to allow parallel digging from both the sides of Ghansoli and Shilphata.
The next part of the project consists of lining, finishing, and waterproofing the tunnel along with the installation of the equipment. The 16 km of remaining tunnel will be constructed using the tunnel boring machines (TBM). The NATM tunnel has an inner width of 12.6 metres and was constructed by using drilling, blasting and surveying work with a support system within the conditions that are geologically challenging.
Once the tunnel is completed, it will be a single tube with a diameter of 13.1 metres which will have space for both the tracks of up and down lines. It will also have several safety measures which will include settlement markers, piezometers, inclinometers, strain gauges, and limited site access. It will also have spaces to pump fresh air for the workers inside the tunnel.
The Mumbai-Ahmedabad high-speed rail corridor of 508 km is the first bullet train project in India. According to NHSRCL, 321 km of viaduct, 398 km of pier, 17 river bridges, 9 steel bridges, and the installation of 4 lakh noise barriers across the stretch of 206 km have been completed.