Afcons Infrastructure Limited creates significant milestones by excavating 7.32 km of 12.75 km-long tunnel under extreme conditions in Jammu & kashmir. Milestone was attained on the Udhampur Srinagar Baramulla Rail Link project (USBRL) on Feb 15, 2022, with the advancement of Tunnel T49 between Sumber and Arpinchala Stations on the Katra-Banihal Section.

T49 is a 12.75 km-long tunnel and to be the longest tunnel of the Indian Railways surpassing the Peer Panjal Tunnel of 11.2 km on the Banihal-Qazigund section. The south portal of Tunnel T49 is located in the picturesque Sumber Village at an altitude of 1,400 m, while the north portal of the tunnel is situated near Arpinchala Village at an altitude of 1,600 m.

Afcons, a critical player in the strategic project, made it to the breakthrough point from the north portal despite considerable geological challenges.

While executing the tunnel from the north portal, Afcons' engineers excavated 4.07 km from a single audit. It is the most critical and longest length implemented by any agency from a single audit. No other agency in the entire USBRL project has excavated such a long distance from a single phase. Amidst the challenge of working in extremely cold conditions (as low as -10 degrees centigrade) during the winter months, the team faced another significant hurdle. There was water ingress of 40-50 litres per second which made tunnelling extremely challenging.

Since they were operating on a downward gradient, on average, they had to dewater nearly 2 lakh kWh units per month.

The water ingress was due to multiple aquifers and nullahs crossing the tunnel alignment, the Project Manager said. Over 60% of the tunnel length was implemented in very poor rock class. But extremely high deformation was noticed in a 1.5 km stretch of the tunnel.

To overcome this, the team adapted different construction techniques such as enlargement of tunnel profile and introduced steel fibre reinforced concrete to speed up the progress. They commenced an excavation in 2015 and throughout excavated under particularly poor geology.

The original scope was later updated to accommodate an additional 3.6 km escape tunnel which brought about a change in alignment. But we were able to complete the entire project within schedule. This tunnel is a significant achievement for Indian Railways and Afcons. From heavy snowfall and heavy rains, which restricted vehicle movement every year, to local issues and extremely poor geology, they are happy to have passed them all and complete a significant assignment for the nation.

Afcons Infrastructure Limited is a construction and engineering firm headquartered in Mumbai and part of Shapoorji Pallonji (SP) Group, which has a legacy of more than 150 years.

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Also read: Railways connects longest tunnel T-49 on Katra-Banihal section