Northern Railway has achieved a major milestone by breaking through T-48 tunnel, the fourth longest tunnel of Indian Railways between Sangaldan and Sumber stations on the 111-km under-construction Banihal-Katra Railway link. The line and level of the tunnel were precisely achieved during the breakthrough which was executed by conducting a blast under the supervision of CEO of the Northern Railways.
T-48 is a twin-tube tunnel consisting of a main tunnel (10.186 km) and an escape tunnel (9.788 km) connected by 24 cross-passages. It has been constructed as per international standards and the provision has been made for rescue and relief operations in emergency situations.
The horseshoe-shaped tunnel connects Sumbar Station Yard on the north side and Bridge No 1 at Dharam village Chinji Nala on the south side. The excavation work of the tunnel was started from two ends namely Dharma Pravesh Darwaza (328 metre) and Kohli Entrance (829 m).
It passes through the Ramban formation of the Young Himalayas and the Muri Thrust at the southern end of tunnel T-48, where the Chinji Nala passes between T-47P-2 and T-48P-1.
The tributaries of the Chenab River like Bhimdasa, Bagdisha and Kohli Nalapass along it made mining a very challenging task. And Dharam to South Drive being the longest drive at 3,940m, made it difficult to maintain an extremely ventilated entrance to mining operations and works.
The North Drive was difficult due to continuous pumping of water from inside the tunnel towards the northern portal as the drive is on a steep slope, weak shear mass and weak terrain and heavy infiltration of water up to 350-400 liters in the north direction.