IIT Mandi: Manali-Leh Rail Faces Hazard Risk
Why in News?
- A study by researchers at the Indian Institute of Technology Mandi says nearly 60 per cent of the proposed Bilaspur-Manali-Leh railway line lies in moderate to high natural hazard zones, The Tribune reported on 31 October 2026.
- The study was published on 30 October in the peer-reviewed journal Geodesy and Geodynamics.
- It names permafrost-induced landslides, avalanches and glacial lake outburst floods as the main threats.
- The researchers recommend detailed geotechnical and cryospheric studies before construction begins.
Key Terminologies
- Permafrost
- Ground that stays frozen for at least two years. When it thaws because of warming, slopes lose strength and can slide or settle, which is a danger to tunnels and tracks.
- Glacial Lake Outburst Flood
- A sudden flood when a lake held by ice or moraine breaks its barrier. It sends water, rocks and debris far down a valley in a short time.
- Avalanche
- A fast slide of snow, ice and rock down a mountain slope. It threatens roads, rail lines and tunnel entrances in high mountains.
- Hazard Susceptibility
- A map-based rating of how likely an area is to see a hazard such as a landslide. The study rated land along the line as very high, high, moderate, low or very low.
- Cryosphere
- The frozen parts of the Earth, such as glaciers, snow and permafrost. A cryospheric investigation checks their condition before building in such areas.
Key Issues
- Hazard Exposure: The study found 7.96 per cent of the mapped area in very high susceptibility, 20.28 per cent in high and 29.32 per cent in moderate zones, according to The Tribune. These add up to about 57.6 per cent, close to the 60 per cent headline.
- Tunnel Dependence: The mapped line is about 275 km long, of which 154 km lies in 62 tunnels, the study says. The Ministry of Railways told the Lok Sabha in December 2025 that the full 489 km line needs nearly 270 km of tunnels.
- Thawing Ground: The study cites permafrost degradation causing thaw-induced slope failures and ground instability. Elevation ranges from about 6,870 feet near Manali to 21,000 feet in Ladakh, and temperatures range from about 35 degrees Celsius to below minus 28 degrees.
- Station Sites: Five of the 15 proposed stations, Chhuchot, Phe Yard, Debring, She Road and Darcha, fall in high susceptibility zones, according to the study.
- Cost Without Timeline: The Railways reply put the cost at about Rs 1.31 lakh crore and said no definite timeline could be given, as approvals from NITI Aayog and the Ministry of Finance are pending.
Key Implications
Positive/Pros/Merits
- Early Warning: The study maps risk before construction, so designers can still change alignments and station sites.
- Method: It examined a 20 km wide zone using nine conditioning factors, such as slope, permafrost zonation, distance to glacial lakes, lithology and geomorphology. This gives a broad risk picture.
- Strategic Value: The Ministry of Defence has designated the line a strategic railway line, according to the Ministry of Railways reply reported by Kashmir Life, so the research supports a project the government treats as a priority.
- Planning Guidance: The advice to carry out geotechnical and cryospheric investigations gives engineers a clear next step.
Negative/Cons/Demerits
- Costly Fixes: Building in very high and high hazard zones will need heavier tunnelling and protection. In analysis, this adds to a project already costed at Rs 1.31 lakh crore.
- Climate Uncertainty: Warming increases permafrost thaw and glacial lake risk, so hazards could grow over the life of the line.
- Ecological Pressure: Construction in a fragile high-altitude area can add to slope disturbance, so careful environmental assessment is needed.
- Study Limits: A susceptibility map shows where hazards are likely, not when they will occur or how severe they will be, so detailed field work is still needed.
Key Initiatives
- Ministry of Railways: In a Lok Sabha reply in December 2025 it said the survey of the 489 km Bilaspur-Manali-Leh line is complete and a Detailed Project Report has been prepared at an estimated cost of about Rs 1.31 lakh crore.
- Ministry of Defence: It has designated the line a strategic railway line because of the difficult Himalayan terrain.
- IIT Mandi Study: Researchers from its School of Civil and Environmental Engineering published the hazard mapping on 30 October 2026 and called for detailed geotechnical and cryospheric studies.
- Approvals: The Railways reply said the project needs consultations with Union Territory administrations and approvals from NITI Aayog and the Ministry of Finance.
The Ministry of Railways says projects are approved on the basis of strategic importance, connectivity, socio-economic impact and financial feasibility. It has said that no definite timeline for the Bilaspur-Manali-Leh line can be given at this stage. The IIT Mandi study adds a hazard assessment to the information available for that decision.
Director's Perspective
Way Forward
- Carry out geotechnical and cryospheric field studies along the line before the final design, as the researchers advise.
- Shift the five stations in high susceptibility zones where feasible, or protect them with engineered defences.
- Install early warning for avalanches and glacial lake outburst floods, with sensors at tunnel portals and valleys.
- Monitor permafrost temperature on the alignment for several years, and share the data with agencies.
- Approve the project in stages, so that the safest sections are built first and risk review continues.
The study does not prove that the line cannot be built, but it shows that the route is among the most hazard-exposed rail projects in the country. A tunnel-heavy design and a strategic purpose make the line important, while permafrost, avalanches and glacial floods make it risky. In a Mains answer, credit the early risk mapping, then conclude that detailed field studies, careful alignment and continuous monitoring must come before any approval.
GS Relevance
Frequently Asked Questions
What did the IIT Mandi study find about the Manali-Leh rail line?
The IIT Mandi study, published on 30 October 2026 in Geodesy and Geodynamics, found that close to 60 per cent of the proposed Bilaspur-Manali-Leh line lies in moderate to high natural hazard zones. It names permafrost landslides, avalanches and glacial lake outburst floods as the main risks.
How long is the proposed Bilaspur-Manali-Leh railway line?
The Ministry of Railways told the Lok Sabha in December 2025 that the line is 489 km long, with an estimated cost of about Rs 1.31 lakh crore. The IIT Mandi study mapped a 275 km section, of which 154 km lies in 62 tunnels.
What is a glacial lake outburst flood?
A glacial lake outburst flood is a sudden release of water when the natural barrier of ice or moraine holding a glacial lake gives way. The IIT Mandi study lists such floods, along with avalanches and permafrost landslides, among hazards for the proposed Manali-Leh railway line.
PYQ Practice — Statement Analysis
1 Permafrost is ground that remains frozen for at least two years.
Thawing of permafrost can cause slope failure and ground instability, as the IIT Mandi study notes.
2 A glacial lake outburst flood is caused by the sudden break of a barrier holding a glacial lake.
The barrier may be ice or moraine, and the flood can travel far down a valley.
3 The IIT Mandi study found that less than 10 per cent of the mapped area lies in very high or high susceptibility zones.
It found 7.96 per cent in very high and 20.28 per cent in high susceptibility zones.