Srinagar Oct 18: Northern Railway on Tuesday achieved a major milestone by breaking through Tunnel T-48, the fourth longest tunnel of Indian Railways between Sangaldan and Sumber stations on Katra-Banihal section of USBRL project.
As per a Northern Railway spokesman, the line and level of the tunnel were precisely achieved during the break-through. 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 ruling gradient inside the tunnel is 01 in 80. The excavation work of the tunnel was started from two ends namely Dharma Pravesh Darwaza (328 m) and Kohli Entrance (829 m).
Tunnel 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. The spokesman said the tunnel has been constructed as per international standards, provision has been made for rescue and relief operations in emergency situations. The tunnel 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 Nala pass along it, making mining a very challenging task.
Dharam to South Drive is the longest drive at 3940 metres, making it difficult to maintain an extremely ventilated entrance to mining operations and works. Simultaneously, the North Drive remained difficult due to the 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, heavy infiltration of water up to 350-400 ltr/s in the north direction.
The tunnel has been constructed by the New Austrian Tunneling Method (NATM), a modern technology of drill and blast processes. The construction work has been entrusted by Northern Railway to M/s IRCON International Limited. The work of excavation of the tunnel was started from both the directions till the hand shaking point.
With the joint efforts of Northern Railway, M/s IRCON and M/s GECPL (Executive Agency), this work which started from both the ends of the tunnel has been completed. "It is the result of careful planning and precise execution of tunneling work. The line and level of the tunnel after break-through remained completely equal at both ends, " the spokesman said.
He said the team of experienced engineers of Northern Railway, M/s IRCON and executive agency M/s Gammon successfully faced all the challenges and achieved a major milestone by breaking through the main tunnel. "During the construction activities of the tunnel, more than 70% workers from the surrounding villages were involved in various construction activities which brought a positive change in the overall socio-economic scenario of the area".
It is noteworthy that T-48 tunnel (10.2 km) in Sumbar area of Ramban district of Jammu and Kashmir is the fourth longest rail transport tunnel in the country. It is noteworthy that all three tunnels longer than this are included in this project.