Manali: Racing to meet the August 2019 deadline for completion of the prestigious 9 Km long Rohtang Tunnel project, army engineers at the site said that work was going on in a critical section of the tunnel where overcoming high load pressure had turned up as a geological surprise for the team.
“From the South Portal,” said Brigadier DN Bhatt, chief engineer Rohtang Tunnel, “excavation of 3627.2 meters stands completed and from the north portal the tunnel tunnel has been dug to a length of 3485.64 meter and only 1907.55 meters of it remains.”
The army engineers speaking to Hill Post added that the tunnel work was now in an area where the high overburden area over south portal was over 1000 meters high and about 1650 meters at north portal.
“Such a heavy overburden causes high load and pressure in the tunnel that poses a lot of challenges for those working deep inside the mountain out there. We are tackling all the problems being faced and hope to achieve a breakthrough (meeting of the South & North portal tunnels) on schedule by July 2017 and complete it by August 2019,” said Brig Dutt.
To hold the pressure and the excavated tunnel in place, the engineering demands a strong system which involves drilling in extra long bolts, thick concrete, steel girders and wire meshes.
These measures are necessary to ensure stability and safety of tunnel and the workers engaged in carrying out the drilling and blasting deep inside the mountains, said Brig Dutt. “Other works involved include kicking lining, arch lining, laying of an emergency tunnel below the tunnel where work is progressing concurrently.”
Speaking about the avalanche protection measures adopted at the construction site Colonel Sanjay Thayplal, Director of Rohtang tunnel said that 13 avalanche protection structures on approach road from Manali to south portal of Rohtang Tunnel had been constructed. Besides the snow galleries, snow bridges and deflection walls laid out were all designed by army engineers at SASA.
About the loose strata encountered during the project execution Rajesh Arora, project manager of SMECKA, the consultant agency for Rohtang Tunnel said, “this type of lose strata of rock was predicted in design in the given time frame.”