The Mumbai Ahmedabad bullet train project saw a major breakthrough on the 4.88 km-long tunnel between Shilphata and Ghansoli. The breakthrough was achieved on Saturday morning, the National High Speed Rail Corporation Limited (NHSRCL) said.
Union railway minister Ashwini Vaishnaw was present at the Ghansoli shaft when this breakthrough was achieved by way of a controlled blast, news agency PTI reported. The tunnel is a part of the 21-km underground stretch between the Bandra-Kurla Complex (BKC) and Shilphata, including a seven-km segment beneath Thane Creek. It was excavated using the New Austrian Tunnel Method (NATM).
With this latest development, the bullet train tunnel now connects the Savali shaft to the tunnel portal at Shilpata, linking it to the viaduct portion of the Mumbai-Ahmedabad High Speed Rail (MAHSR) project, the NHSRCL stated in a release.
The excavation for this tunnel began back in May 2024 in three phases; the first breakthrough was achieved on July 9 of a 2.7-km continuous section. Further, an additional intermediate tunnel was built to allow simultaneous excavation from both Ghansoli and Shilphata sides.
{{/usCountry}}The excavation for this tunnel began back in May 2024 in three phases; the first breakthrough was achieved on July 9 of a 2.7-km continuous section. Further, an additional intermediate tunnel was built to allow simultaneous excavation from both Ghansoli and Shilphata sides.
{{/usCountry}}The next phase of the project will involve waterproofing, lining and finishing the tunnel as well as equipment installation. The remaining 16 km of tunnelling will be executed using tunnel boring machines (TBMs).
The NATM tunnel has an internal width of 12.6 metres and was constructed using drilling, blasting, survey works, and support systems under challenging geological conditions.
Once completed, the tunnel will be a single tube with a 13.1-metre diameter structure accommodating twin tracks for both up and down lines.
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It will also feature comprehensive safety measures, including settlement markers, piezometers, inclinometers, strain gauges and restricted site access. There will also be accommodations for pumping fresh air for workers inside the tunnel.
The 508 km-long Mumbai-Ahmedabad high-speed rail corridor is India's first bullet train project. According to the NHSRCL, work has been completed on 321 km of viaduct, 398 km of pier, along with 17 river bridges, nine steel bridges, and the installation of over four lakh noise barriers across 206 km.
The track bed has been completed along 206 kilometres, and over 2,000 overhead equipment masts have been installed, covering 48 kilometres of the mainline viaduct, the statement said.