The main tunnel of T-49, the longest tunnel of Indian Railways, between Sumber and Arpinchala station of Katra-Banihal section of Udhampur- Srinagar-Baramulla Rail Link (USBRL) project has been completed.
“Breakthrough was achieved today in the presence of A K Khandelwal CAO/USBRL along with NR team, IRCON officers and the officers of Messrs HCC and Messrs AFCONS,” officials informed.
Officials said that out of 272 km length of the USBRL project, 161 km project was already commissioned and operationalized.
“The work of an intervening stretch of 111 km between Katra-Banihal is under progress at a rapid pace. Katra-Banihal section is traversing through hilly terrain of lower Himalayas, in which geology is a major challenge. It has several major bridges and very long tunnels which are under construction at different stages,” they stated.
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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.