Engineering marvel
27 Main Tunnels, 8 Escape tunnels on the Katra-Banihal section
WAJAHAT SHABIR
SRINAGAR: Believe it or not, Udhampur-Srinagar-Baramulla Railway Line (USRBL), a 272 kilometre stretch, has over 38 tunnels, which stand at a length of 38 Tunnels with a total length of 119 Km.
Sharing details, a senior official in the Railway Department said, “USRBL project has 38 Tunnels with a total length of 119 Km. adding that he said, The Sumber-Khari T-50, 12.75 Km and the Pir Panjal T-80, 11.2 Km are India’s longest transportation tunnels.
There are 931 Bridges having combined length of 13 Km. The Chenab Bridge (Bridge-44), the highest railway bridge in the world and Anji Bridge (Bridge-35), Indian Railway’s first cable stayed rail bridge are special bridges on the project, railway official said.
There are 27 Main Tunnels and 8 Escape tunnels on the Katra-Banihal section. 97 km route of the 111 km section is through tunnels. There are four tunnels of more than 9 km in length. The tunnel T-50, which lies between Sumber and Khari in Ramban is 12.75 Km and is the longest transportation tunnel in India, he said.
Parallel escape tunnels have been constructed along with cross passages at every 375 m to facilitate rescue & restoration work in emergencies as per international standards, he said.
Tunnel T-33: Most complex and critical component of the Katra-Banihal railway route, situated at the section, spans 3.20 km between Katra and Reasi stations and stands as the inaugural block section of this vital railway route.
Tunnel T-33 traverses the lesser Himalayas navigating highly jointed and fractured base rocks. The tunnel alignment of T-33 encounters the Main Boundary Thrust (MBT) presenting formidable geological and geotechnical challenges. Tunnelling excavation for Tunnel T-33, which started on Oct. 13, 2017 led to prolonged halts in tunnel excavation.
Subsequently strategic shift to the system of tunneling from NATM was initiated in March 2020. This approach incorporated deep drainage pipes, chemical grouting, steel supports and shotcreting. Adopting the I-system of Tunnelling proved instrumental in overcoming the challenges posed by the MBT enabling the successful completion of Tunnel T-33.
Tunnel T-34: With a length of 5.099 Km, comprises of twin tubes i.e. Main Tunnel (MT) for train operations and a parallel Escape Tunnel (ET) for safety and rescue. The alignment of tunnel T-34 falls between Pai-Khad on portal P1 and Anji Khad connecting Indian Railway’s First cable-stayed bridge at portal P2.
Tunnel T-36: one of the challenging tunnels along this alignment located in the outer Himalayas with a length of 5.96 Km, comprises of Main Tunnel (MT) for train operations and a parallel Escape Tunnel (ET) for safety and rescue. It starts immediately after the Reasi railway station in villages Gran, initial 86 m of tunnel is a wider section to accommodate Reasi yard.
Tunnel T-42: Tunnel T-42, spanning a total length of 9.26 Km, serves as a crucial link connecting Dugga yard with Sawalkote station yard. The main tunnel comprises a single section length of 8.0 Km and a wider section of 1.2 Km, designed to accommodate both station yards at Dugga and Sawalkote.
Tunnel T-43: Lies in the Sawalkote – Sangaldan block section. It’s a 6.284 Km-long tunnel located in the districts of Reasi and Ramban. T-43 faced challenges from tough geology of subathu formation and the presence of methane gas.
Tunnel T-44: With a length of 11.16 Km, stands as the third-longest tunnel in Indian Railways. The North Portal is situated in village Sangaldan, while the South Portal is located in the village IND. The alignment of T-44 passes through the challenging Murre formation, characterized by folded, overthrust, and faulted rocks due to high tectonic activities in the Himalayas. Tunnel T-44 comprises two tubes with a Modified Horse Shoe cross-section — the Main Tunnel and an Escape Tunnel. Constructed using the advanced NATM, excavation was done from both portals, three additional adits at Chakani, Barala, and Chachuwa, with a combined length of approximately 1.75 Km, were constructed to create additional faces for faster progress.
Tunnel T-49: Boasting a length of 10.18 Km, is a modified horseshoe-shaped tunnel interconnecting Sumber Station Yard on the North side to Bridge no. 242 over Chinji-nallah at Dharam village on the South side. This twin-tube tunnel consists of the Main Tunnel (10.18 km) and an Escape Tunnel (9.80 Km), interconnected by 24 cross-passages. Several Nallahs viz. Bhimdasg, Bagdisha, and Kohli Nallah, crossing over the tunnel alignment posed challenges of heavy ingress of ground water during tunneling.
Tunnel T-50: Having a length of 12.77 Km is India’s Longest Transportation Tunnel comprising of Main Tunnel (MT) for train operations and a parallel Escape Tunnel (ET) for safety and rescue. This tunnel is in Sumber-Khari section. NATM was successfully used for the construction of this tunnel. Excavated through Ramban & Ramsu formations, it encountered rocks of Precambrian age. The South Portal lies in the picturesque Sumber valley in Sumber village and the North Portal near Arpinchala village in Mahu-Mangat valley adds to the grandeur of this engineering marvel.
