Zojila tunnel breakthrough: Why digging through the Himalayas is an engineering challenge

📌 Summary:

• Breakthrough achieved on the 13-km Zojila Tunnel (altitude 11,578 ft) — India's longest road tunnel nears completion
• Himalayan tunnelling is uniquely hard: extreme altitude, temperatures down to -30℃, deadly avalanches (2 workers died near Sonamarg in Jan 2023; 172 trapped)
• Geological risk: the Himalayas are a young, tectonically active range ("ocean floors pushed upwards"); strata vary metre-to-metre — loose rock, boulders, water ingress; mountains store vast water and have sheer/strain zones
• New Austrian Tunneling Method (NATM) used: selective blasting → walls secured with shotcrete (sprayed concrete) and rock bolts; top half excavated first, then bottom
• Engineers fit drainage pipes for gradual water release to prevent pressure build-up/collapse; alignment and shape tweaked to skirt weak segments

🎯 UPSC Relevance: GS3 Infrastructure / GS1 Geography — strategic all-weather connectivity to Ladakh, Himalayan tectonics, disaster-resilient engineering

📝 Prelims Facts:

• Zojila Tunnel: 13 km, ~11,578 ft; India's longest road tunnel; under Zojila Pass (Srinagar–Leh axis)
• Method: New Austrian Tunneling Method (NATM)
• Himalayas: young fold mountains, tectonically active

🔑 Key Term: NATM — a tunnelling method that uses the rock's own load-bearing capacity, with staged excavation and immediate support via shotcrete and rock bolts