Union Railway Minister Ashwini Vaishnaw inaugurated the completion of a 5-kilometre tunnel stretch between Ghansoli and Shilphata in Thane district of Maharashtra of Mumbai–Ahmedabad Bullet Train Project on Saturday, September 20.
The newly completed 4.881 km tunnel, constructed using the advanced NATM (New Austrian Tunneling Method), is an integral part of the ambitious 21 km undersea stretch that will connect Bandra Kurla Complex (BKC) in Mumbai to Shilphata, including a 7 km section beneath Thane Creek.
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Speaking at the occasion, Minister Vaishnav said, "A significant milestone has been achieved today in the Mumbai–Ahmedabad Bullet Train Project. A tunnel is being constructed beneath the Thane creek between Mumbai and Thane, under the sea—a first for India."
"This area will benefit greatly from it. It will also have a good impact on the economy of this region... Many technologies used in this project have been developed in India itself. Many machines are now being exported," he said further.
The Mumbai–Ahmedabad Bullet Train, stretching over 508 kilometres, aims to reduce travel time between the two cities to just over two hours, with trains running at speeds up to 320 km/h. The project is progressing rapidly, with the Gujarat portion expected to be completed by December 2027 and full completion targeted for December 2029.
With the latest breakthrough, the bullet train tunnel now connects the Savali shaft to the tunnel portal at Shilphata, linking it to the viaduct portion of the Mumbai-Ahmedabad High Speed Rail (MAHSR) project, the NHSRCL stated in a release.
The NHSRCL said that excavation of the tunnel began in May 2024 in three phases, and the first breakthrough of a 2.7 km continuous section was achieved on July 9. An additional intermediate tunnel (ADIT) was built to allow simultaneous excavation from both Ghansoli and Shilphata sides. 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, it stated.
The corporation said that the next phase will involve waterproofing, lining, finishing, and equipment installation, while the remaining 16 km of tunnelling will be executed using tunnel boring machines (TBMs). The completed tunnel will be a single-tube, 13.1-metre diameter structure accommodating twin tracks for both up and down lines.
The corporation also highlighted comprehensive safety measures, including settlement markers, piezometers, inclinometers, strain gauges and restricted site access, along with arrangements to pump 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 construction has been finished on 206 km, and more than 2,000 overhead equipment masts have been installed covering 48 km of the mainline viaduct, it stated.