Mumbai-Ahmedabad Bullet Train: 1st mountain tunnel bored in JUST 10 months
On October 5, NHSRCL achieved another milestone with the breakthrough of a mountain tunnel. This is the first mountain tunnel for the Mumbai-Ahmedabad High Speed Rail (MAHSR) corridor project with six more to go.
Located 1 km away from Zaroli Village of Umbergaon Taluka in Valsad district of Gujarat, the tunnel has been completed in just 10 months, as per reports. The single tube horse-shoe shaped path has two tracks of 350 m in length each, a diameter of 12.6 m, and a height of 10.25 m.
The tunnel is being assembled by applying New Austrian Tunnelling Method (NATM). This method has proved to be very useful in sophisticated and diversified geological conditions where forecasting of the rock mass is difficult due to rapidly changing geology. After geologists carefully assess the rocks, support paraphernalia is selected and installed such as steel ribs, lattice girder, shotcrete and rock bolts.
Procedures such as marking of drill holes, charging of explosives, controlled blasting, removal of muck (blasted rock pieces) and installation of primary support which includes steel ribs, lattice girder, shotcrete, rock bolts is based on the type of rocks as assessed by geologist after each blast.
Notably, the project is scheduled to be completed by 2026.