JAMMU: Northern Railway on Tuesday 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 line.
The line and level of the tunnel were precisely achieved during the breakthrough which was executed by conducting a blast under the supervision of Chief Executive Officer of the Northern Railways S P Mahi, a Railway official said.
He said 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).”
The official said the 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 tunnel has been constructed as per international standards and the provision has been made for rescue and relief operations in emergency situations, the official said.
He said 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, the official said.
He said 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 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 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 official said, adding the construction work has been entrusted by Northern Railway to Messrs IRCON International Limited.
The work of excavation of the tunnel was started from both the directions till the hand shaking point, he said.
“With the joint efforts of Northern Railway, M/s IRCON and M/s GECPL (Executive Agency), this work which started from both ends of the tunnel has been completed flawlessly. 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,” he 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 per cent 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, the spokesman said.
He said the T-48 tunnel (10.2 km) in Sumbar area is the fourth longest rail transport tunnel in the country following the 12.6km tunnel T-49 between Sumber and Arpinchala stations, the longest tunnel of Indian Railways, which was completed in January this year.
The official said Udhampur-Srinagar-Baramulla Railway Link (USBRL) is a national project which is likely to be completed by next year.
Of the 272-km USBRL project, the work on 161 km was commissioned in phases. The first phase of 118-km Qazigund-Baramulla section was commissioned in October 2009, followed by the 18-km Banihal-Qazigund in June 2013 and the 25-km Udhampur-Katra in July 2014.
The work on the intervening stretch of 111 km between Katra and Banihal is under progress and is likely to be completed by next year, the official said, adding the Katra-Banihal section is traversing through the hilly terrain of the lower Himalayas, where geology is a major challenge. It has a total of 37 bridges and 35 tunnels, he said.