Navi Mumbai: Excavation of 394-meter tunnel for Mumbai-Ahmedabad bullet train completed

The 394 metre-long tunnel`s excavation for the Mumbai-Ahmedabad bullet train project was completed on Monday/ Screengrab

The National High Speed Rail Corporation Ltd (NHSRCL) announced on Monday the completion of excavation work for a 394-metre-long tunnel in Navi Mumbai, which is part of the Mumbai-Ahmedabad bullet train project.

The excavation of the additionally driven intermediate tunnel (ADIT) at Ghansoli is a crucial milestone in the building of a 21-kilometre-long tunnel connecting the Bandra-Kurla Complex and Shilphata in Maharashtra. The excavation effort, which began on December 6, 2023, was finished in six months using 214 controlled bursts and 27,515 kg of explosives under expert supervision, reported PTI.

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According to the report, the 26-metre-deep inclined ADIT will make it easier to build a 3.3-kilometre tunnel utilising the New Austrian Tunnelling Method (NATM), which allows for simultaneous tunnelling access from both sides. Of the whole 21 km tunnel, 16 km will be excavated by tunnel boring machines (TBMs) and the remaining 5 km with NATMs.

The ADIT will offer direct vehicular access to the main tunnel during construction and operations, as well as emergency evacuation. The NHSRCL stated that construction activities for the 21 km tunnel, which includes a 7 km stretch beneath the sea at Thane Creek, are moving quickly.

Three shafts are being built at BKC, Vikhroli, and Sawli near Ghansoli to facilitate the 16 km TBM-excavated tunnel. The Mumbai-Ahmedabad High Speed Rail Corridor project, at Rs 1.08 lakh crore, is being funded by the Central government, the states of Gujarat and Maharashtra, and a low-interest loan from Japan, the report added.

NHSRCL, per the PTI report, stated in their release, "The excavation work for ADIT began on December 6, 2023, and the entire length of 394 metres was excavated in six months. A total of 214 controlled blasts were carried out using 27,515 kg of explosives under the supervision of experts, and a high level of instrumentation was used to ensure safe excavation."

The release further stated, "The 26-meter-deep inclined ADIT will facilitate the construction of an approximately 3.3 km tunnel through the New Austrian Tunnelling Method (NATM) by allowing simultaneous access for tunnelling about 1.6 metres on each side. Of 21 km of tunnel in the bullet train project, 16 km will be excavated using tunnel boring machines (TBMs), while NATM will be used for the remaining 5 km."

"The ADIT will give direct vehicular access to the main tunnel during construction and operations and may also be used for evacuation in emergencies," the release added.

With PTI inputs