Bullet train project: Breakthrough of first mountain tunnel achieved

Gandhinagar: National High-Speed Rail Corporation Limited today announced it has achieved a major milestone today with the breakthrough of the mountain tunnel for the Mumbai-Ahmedabad High-Speed Rail corridor project.

This is the first mountain tunnel that has been completed in a short span of 10 months.

The tunnel is located at around 1 km away from Zaroli Village of Umbergaon Taluka in the Valsad district of Gujarat. The tunnel structure comprises of tunnel, tunnel portal, and other connecting structures like a tunnel entrance hood.

The tunnel is being constructed by the New Austrian Tunnelling Method (NATM) which includes the following procedure:

1. Marking of drill holes on the tunnel face
2. Drilling of holes
3. Charging of explosives
4. Controlled Blasting
5. Removal of muck (blasted rock pieces)
6. Installation of primary support which includes steel ribs, lattice girder, shotcrete, and rock bolts based on the type of rocks as assessed by geologist after each blast

Salient features of the mountain tunnel:

• Total Tunnel Length: 350 m
• Diameter of Tunnel: 12.6 m
• Height of Tunnel: 10.25 m
• Tunnel Shape: Single tube horse-shoe shaped
• Number of tracks: 2 Tracks

Additional Information

• Mumbai Ahmedabad High-Speed Rail (MAHSR) corridor will have seven mountain tunnels, which will be constructed using the NATM Method.  DeshGujarat