The National High Speed Rail Corporation Ltd (NHSRCL) on Monday said the excavation work has been completed for a 394-metre-long tunnel in Navi Mumbai for the Mumbai-Ahmedabad bullet train project.
NHSRCL, the executing body for the ambitious project, said that the completion of an additionally driven intermediate tunnel (ADIT) at Ghansoli will expedite the construction of a 21 km long tunnel between the Bandra-Kurla Complex and Shilphata in Maharashtra.
"The excavation work for ADIT began on December 6, 2023, and the entire length of 394 metres was excavated in six months," NHSRCL said in a release.
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, it said.
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, the release said.
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, it said.
"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 said.
The NHSRCL said the construction activities related to the 21 km long tunnel from the Mumbai bullet train station at BKC to Shilphata were progressing at a fast pace. About 7 km stretch of this tunnel will be under the sea at Thane Creek (Intertidal zone).
Three shafts at BKC, Vikhroli, and Sawli near Ghansoli are under construction, and these will facilitate the construction of a 16 km-long tunnel through TBMs, it said.
The total cost of the Mumbai-Ahmedabad High Speed Rail Corridor project is pegged at Rs 1.08 lakh crore, and as per the shareholding pattern, the Central government is to pay Rs 10,000 crore to the NHSRCL, while the two states involved, Gujarat and Maharashtra, are to pay Rs 5,000 crore each.
The rest is to be funded by Japan through a loan at 0.1 per cent interest.
