New Delhi, Oct 6 : In a major development in the Mumbai-Ahmedabad 508-km-long High Speed Rail train project, the National High Speed Rail Corporation Limited (NHSRCL) has achieved a major milestone with the breakthrough of a mountain tunnel for the high speed rail corridor project, a spokesperson said. A NHSRCL spokesperson here said that this is the first mountain tunnel which has been completed in a short span of 10 months. NHSRCL spokesperson Sushma Gaur said that the tunnel is located at around 1 km away from Zaroli village of Umbergaon taluka in Gujarat's Valsad district. She added that the tunnel structure comprises of tunnel, tunnel portal and other connecting structures like tunnel entrance hood. She said that the tunnel is being constructed by New Austrian Tunnelling Method (NATM) which includes the procedure like marking of drill holes on the tunnel face, drilling of 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 based on the type of rocks as assessed by geologist after each blast. She also pointed out the mountain tunnel is 350 m in length and its diameter is 12.6 m while the height of the tunnel is 10.25 m. She said that the single tube horse-shoe shaped tunnel has two tracks. Gaur also added that there are a total of seven tunnels on the Mumbai-Ahmedabad high speed corridor, which will be constructed using the NATM method. The foundation stone for India's first Mumbai-Ahmedabad High Speed Rail Project was laid in September 2017 by Prime Minister Narendra Modi and his then Japanese counterpart Shinzo Abe. The project is scheduled to be completed by 2026. /IANS