USBRL: Breakthrough achieved for India’s longest tunnel T49.
February 15, 2022, breakthrough of India’s longest tunnel T49 was achieved. This tunnel named T49 is 12.758 km long and is situated between Sumber and Arpinchala stations on the Katra-Banihal section of the 272-km long Udhampur Srinagar Baramulla Rail Link Project (USBRL).
The...
more... line and level of the tunnel was precisely achieved in break-through according to a statement by Northern Railway(NR). The 12.758-km long T49 tunnel will replace the existing longest tunnel over Indian Railways, the 11.2-km long Peer Panjal tunnel between Banihal-Qazigund section on the same rail line.
The south portal of tunnel T49 is located at an altitude of 1400 meters in the picturesque Sumber village, 45 km from the district hqs Ramban in Jammu and Kashmir. The north portal of the tunnel is located at an altitude of approximately 1600 meters near Arpinchala village Tehsil Khari, district Ramban, in the Mahu-Mangat Valley.
T49 tunnel has two tubes, the first is the main tunnel and the other an escape tunnel. It has a ruling gradient 1 in 80 and designed speed of 100 kmph. Constructed by the NATM technique (New Austrian Tunneling Method), which uses drill and blast method, the tunnel’s cross section is shaped like a modified horse shoe.
To facilitate construction, three adits namely Urnihal Adit, Hingni Adit and Kundan Adit have also been constructed. [Adit is a nearly-horizontal passage or tunnel that provides access to and from underground workings in a tunnel].
An escape tunnel has also been built parallel to the main tunnel as per international standards. The escape tunnel is connected by cross passages at an interval of 375 metres to facilitate rescue and restoration work.
NR has assigned construction works to IRCON International which in turn has assigned works in two packages for execution-one to Afcons Infrastructure, 7.658-km long from north portal and the other to HCC, 5.1-km long from south portal.
During construction several challenges such as shear zone, perched aquifer,highly jointed rock mass, rock problems of squeezing and high ingress of water were successfully overcome by the engineers of NR, IRCON, Afcons and HCC.Locals were employed during construction for various works.
