A section of the T-49 tunnel after it was connected by the engineers of Indian Railways.
The Indian Railways successfully achieved the line and level breakthrough of the 12.758 kilometre long T-49 tunnel in Jammu and Kashmir. The major milestone was achieved on Tuesday, informed the Northern Railway, which connected the two ends of the tunnel between Sumber and Arpinchala stations of Katra-Banihal section of Udhampur-Srinagar-Baramulla Rail Link (USBRL) project.
T-49 is going to be the longest tunnel of Indian Railways, surpassing Peer Panjal Tunnel of 11.2 km length constructed by USBRL on the Banihal-Qazigund section, the Northern Railway said on Twitter.
Koo AppExpanding Network, Connecting Nation After negotiating several challenges, the break-through of India's Longest Transportation Tunnel T-49 at Ramban district, J&K (12.75 kms) between Katra-Banihal section achieved successfully, yesterday. #Infra4India- Ministry of Railways (@RailMinIndia) 16 Feb 2022
Here are key things to know about T-49:
- The south portal of the tunnel is located at an altitude of 1400 metres, while its north portal is located at an altitude of 1600 metres.
- The T-49 tunnel has been constructed using the New Austrian Tunneling Method (NATM), a modern technique of drill and blast method. The Northern Railway said that the cross section profile of the tunnel is modified horseshoe-shaped.
- The NATM is also known as the sequential excavation method (SEM). It uses the strength of the surrounding soil to the greatest extent possible to strengthen the tunnel structure. The NATM promotes constant monitoring.
- Being an SEM, the operation occurs sequentially to take most advantage of the ground conditions.
- T-49 tunnel has two tubes - one is the main tunnel and other being escape tunnel. As per international standards, the escape tunnel being constructed parallel to the main tunnel is connected by cross passages at an interval of 375m to facilitate rescue and restoration work.
- The tunnel has a ruling gradient 1 in 80 and designed speed of 100 kmph.
- The Northern Railway said that during construction activities, local population was employed by agencies for various works.
- Out of 272 km length of USBRL project, 161 kilometres has already been commissioned and operationalised.
- The work of the intervening stretch of 111 kilometre between Katra Banihal is under progress at rapid pace, the railways said.
- It added that several challenges were encountered in the course of construction such as shear zone, perched aquifer, and highly jointed rock mass, rock problems of squeezing and high ingress of water.
