After slow progress initially, work in Maharashtra for the bullet train project is underway in full swing now. Last month, the NHSRCL invited bids for the ‘Design, Supply and Construction of Track and Track related Works including Testing and Commissioning for Double Line High-Speed Railway’ in the state
It is difficult to accommodate a new infrastructure project in old and congested cities due to land unavailability. Mumbai was no different when planning started for India’s first bullet train project connecting the city with Gujarat’s Ahmedabad. And it was decided that the entire stretch of the high-speed corridor in Mumbai would be underground.
The city will have a 21-km-long tunnel between Bandra Kurla Complex in Mumbai and Shilphata in Thane that will also include India’s first undersea tunnel at Thane Creek. Out of 21 km of tunnelling work, 16 km is through Tunnel Boring Machines (TBM) and the remaining five kilometre is through the New Austrian Tunnelling Method (NATM).
News18 has learnt that as of last week, 1.36 km has been excavated in NATM, while for the remaining part, shafts are ready at three locations.
“For the 16 km TBM part, shafts are ready for lowering TBMs and in the 5 km NATM part, more than a kilometre has been excavated so far,” an official told News18 on condition of anonymity.
The tunnel also includes seven kilometres of India’s first undersea tunnel at Thane Creek.
National High-Speed Rail Corporation Limited (NHSRCL), building the bullet train project, is also using various geotechnical instruments including inclinometers, vibration monitors, ground settlement markers, and tilt meters at and around construction sites for monitoring tilt, settlement, vibration, cracks and deformation.
“These instruments play a crucial role in making sure that neither is there any risk to ongoing underground works like excavation and tunnelling nor to the structures surrounding the site,” they said.
Further, one Additionally Driven Intermediate Tunnel (ADIT) has also been completed for easing the work on the main tunnel. The ADIT was planned to facilitate additional access to the underground/undersea tunnel for faster construction progress The ADIT adds two additional NATM faces for the excavation work in addition to Shilphata.
The 394-metre ADIT tunnel was ready in just six months in May this year. This 11 metre x 6.4 metre ADIT gives direct vehicular access to the main tunnel during construction and operations. It also acts as an evacuation path in case of any emergency.