Nepal maintains roads but ignores the slopes holding them up
Each monsoon, when highways close after heavy rain or traffic halts due to rock fall, we usually see only the immediate crisis. A landslide occurs, excavators move in, debris is cleared, and traffic resumes, until the next failure. We treat each landslide as a crisis to be managed, not a pattern to be understood. What often goes unnoticed is the deeper, recurring problem beneath these disruptions: Nepal’s highway maintenance system still focuses largely on pavement, while the slopes that physically support our roads receive little systematic attention.
Not every landslide can be prevented. Complex geology, extreme rainfall, shifting land use, and the interplay of natural and human forces will continue to trigger new failures. However, evidence indicates that proactive slope management and risk-based prioritization might have eliminated or significantly reduced a large portion of road obstructions and economic losses in Nepal. Over time, the country’s heavy reliance on emergency response has blurred the boundary between unavoidable natural hazards and avoidable institutional neglect.
The data increasingly make this clear.
A growing economic burden and a clear warning spike
Department of Roads (DoR) records for fiscal years 2077–2081 BS reveal a troubling trend. Roadside landslide incidents and road closures remained relatively stable between 2077 and 2080 BS, but escalated sharply in 2081 BS. In that single year, reported roadside landslide events exceeded 800, compared to roughly 250 in preceding years, an increase of more than 220 percent.
The economic damage was even more alarming. Estimated closure-based losses rose nearly fourfold in 2081 BS, surpassing Rs 4,000 crore. These figures primarily reflect the direct cost associated with road closures and do not fully capture wider economic disruptions such as travel delays, traffic congestion, supply-chain interruptions, and lost productivity.
This disparity matters. Nepal’s largest losses from landslides are not the costs of clearing debris or rebuilding damaged structures. They arise from immobilized movements including stalled freight, delayed services, and inflated transport costs. Nepal’s highways function as narrow economic lifelines. When they fail, the consequences ripple far beyond the landslide site, affecting regional and national economy.
Emergency response has become routine
Longer-term maintenance records reinforce the same pattern. DoR data for fiscal years 2069–2078 BS show total maintenance budgets rising steadily, alongside recurring emergency maintenance expenditure year after year, largely driven by post-landslide debris clearance and rapid traffic reopening.
There exists a difference in between identified needs and actual budget allocation for slope-related maintenance activities. DoR records show that demand for slope management, driven by aging protection works, expanding road networks, and increasing climate stress, has risen steadily over time. Yet allocations remain substantially lower, with no effort to close the gap.
This chronic underinvestment ensures that known vulnerabilities persist, gabion walls deform, wire mesh corrodes or tears, rock bolts loosen, bio-engineered slopes degrade, and over-steepened cut slopes remain untreated. Instead of being addressed through timely maintenance, these weaknesses are left to fail, only to reappear as emergencies, at far greater economic and social cost.
Why slopes matter as much as pavement
Nepal’s road network has expanded dramatically, from about 4,000 km in 1980 to over 100,000 km today. Nearly 80 percent of the country’s strategic roads traverse hills and mountains, where road performance depends more on slope stability and drainage than on the quality of asphalt.
The difference in consequences is fundamental. Poor pavement leads to uncomfortable travel and higher vehicle wear. Slope failure, by contrast, causes complete road closure, economic paralysis, and sometimes weeks of isolation for entire regions. In mountainous terrain, treating slopes as a secondary concern is not merely inefficient, it is dangerous.
Nepal has already invested heavily in slope protection works, including retaining walls, wire mesh, rock bolts, drainage channels, check dams, and bio-engineering measures. Yet these systems are rarely treated as maintainable assets. These are slow but visible processes, ignored until collapse forces costly emergency intervention.
The Narayanghat–Mugling road illustrates this problem clearly. Along this corridor, advanced slope stabilization structures and monitoring instruments were installed at considerable cost. Today, many monitoring systems are non-functional or no longer tracked, and upstream check dams designed to protect the highway are repeatedly damaged during monsoon seasons with little maintenance response. Similar patterns exist across Nepal’s highways, where expensive protective works gradually lose effectiveness due to neglect.
The issue is not only maintenance, but also prioritization. Each monsoon triggers dozens of roadside landslides, yet there is little evidence that budget demonstrate systematic risk-based prioritization: distinguishing which slopes are critically unstable, which pose high economic risk, and which can be managed through low-cost preventive measures. Without such differentiation, resources are spread thinly or deployed only after failure occurs.
An integrated approach to maintenance
International experience shows this cycle can be broken. Transportation agencies facing recurrent slope failures have adopted systematic slope management systems that integrate inventories, inspection schedules, condition databases, and predictive analysis.
Nepal’s own research on Himalayan highways points in the same direction. Combining pavement condition data with slope-failure susceptibility mapping using GIS allows smarter maintenance prioritization, by both functional importance and failure risk.
Four practical steps stand out.
First, treat slopes as assets. Every retaining wall, drainage structure, rockfall barrier, and check dam should be inventoried and tracked, just like bridges. Nepal already has technical guidance, including the DoR’s Guide to Road Slope Protection Works (2003), but these recommendations remain largely absent from routine maintenance.
Second, inspect systematically. Maintenance contracts should require regular slope inspections using standard checklists, enabling early detection of warning signs such as cracking, seepage, deformation, and drainage blockage.
Third, budget for prevention. Slope work should no longer be buried under “emergency maintenance.” Routine budgets must explicitly fund mesh repair, bolt tightening or replacement, vegetation management, erosion control, and minor stabilization work. Evidence consistently shows that every rupee spent on prevention saves several rupees in future repair and closure-related losses, especially in mountain highways where closure costs dominate.
Finally, the integrated system is a must. Pavement and slopes are managed by the same agency yet treated as separate problems. Integrated planning improves technical outcomes and makes better use of limited public resources.
Beyond pavement
The sharp escalation in 2081 BS should be treated as a warning, not as anomaly. Climate change is intensifying rainfall extremes, increasing the likelihood that small maintenance defects will turn into major failures. In mountain highways, pavement is merely the visible surface. Slopes are the foundation.
Until Nepal’s maintenance philosophy reflects that reality, roadside landslides will continue to surprise us, though the warning signs have been clear all along.
Nepal maintains roads but ignores the slopes holding them up
Each monsoon, when highways close after heavy rain or traffic halts due to rock fall, we usually see only the immediate crisis. A landslide occurs, excavators move in, debris is cleared, and traffic resumes, until the next failure. We treat each landslide as a crisis to be managed, not a pattern to be understood. What often goes unnoticed is the deeper, recurring problem beneath these disruptions: Nepal’s highway maintenance system still focuses largely on pavement, while the slopes that physically support our roads receive little systematic attention.
Not every landslide can be prevented. Complex geology, extreme rainfall, shifting land use, and the interplay of natural and human forces will continue to trigger new failures. However, evidence indicates that proactive slope management and risk-based prioritization might have eliminated or significantly reduced a large portion of road obstructions and economic losses in Nepal. Over time, the country’s heavy reliance on emergency response has blurred the boundary between unavoidable natural hazards and avoidable institutional neglect.
The data increasingly make this clear.
A growing economic burden and a clear warning spike
Department of Roads (DoR) records for fiscal years 2077–2081 BS reveal a troubling trend. Roadside landslide incidents and road closures remained relatively stable between 2077 and 2080 BS, but escalated sharply in 2081 BS. In that single year, reported roadside landslide events exceeded 800, compared to roughly 250 in preceding years, an increase of more than 220 percent.
The economic damage was even more alarming. Estimated closure-based losses rose nearly fourfold in 2081 BS, surpassing Rs 4,000 crore. These figures primarily reflect the direct cost associated with road closures and do not fully capture wider economic disruptions such as travel delays, traffic congestion, supply-chain interruptions, and lost productivity.
This disparity matters. Nepal’s largest losses from landslides are not the costs of clearing debris or rebuilding damaged structures. They arise from immobilized movements including stalled freight, delayed services, and inflated transport costs. Nepal’s highways function as narrow economic lifelines. When they fail, the consequences ripple far beyond the landslide site, affecting regional and national economy.
Emergency response has become routine
Longer-term maintenance records reinforce the same pattern. DoR data for fiscal years 2069–2078 BS show total maintenance budgets rising steadily, alongside recurring emergency maintenance expenditure year after year, largely driven by post-landslide debris clearance and rapid traffic reopening.
There exists a difference in between identified needs and actual budget allocation for slope-related maintenance activities. DoR records show that demand for slope management, driven by aging protection works, expanding road networks, and increasing climate stress, has risen steadily over time. Yet allocations remain substantially lower, with no effort to close the gap.
This chronic underinvestment ensures that known vulnerabilities persist, gabion walls deform, wire mesh corrodes or tears, rock bolts loosen, bio-engineered slopes degrade, and over-steepened cut slopes remain untreated. Instead of being addressed through timely maintenance, these weaknesses are left to fail, only to reappear as emergencies, at far greater economic and social cost.
Why slopes matter as much as pavement
Nepal’s road network has expanded dramatically, from about 4,000 km in 1980 to over 100,000 km today. Nearly 80 percent of the country’s strategic roads traverse hills and mountains, where road performance depends more on slope stability and drainage than on the quality of asphalt.
The difference in consequences is fundamental. Poor pavement leads to uncomfortable travel and higher vehicle wear. Slope failure, by contrast, causes complete road closure, economic paralysis, and sometimes weeks of isolation for entire regions. In mountainous terrain, treating slopes as a secondary concern is not merely inefficient, it is dangerous.
Nepal has already invested heavily in slope protection works, including retaining walls, wire mesh, rock bolts, drainage channels, check dams, and bio-engineering measures. Yet these systems are rarely treated as maintainable assets. These are slow but visible processes, ignored until collapse forces costly emergency intervention.
The Narayanghat–Mugling road illustrates this problem clearly. Along this corridor, advanced slope stabilization structures and monitoring instruments were installed at considerable cost. Today, many monitoring systems are non-functional or no longer tracked, and upstream check dams designed to protect the highway are repeatedly damaged during monsoon seasons with little maintenance response. Similar patterns exist across Nepal’s highways, where expensive protective works gradually lose effectiveness due to neglect.
The issue is not only maintenance, but also prioritization. Each monsoon triggers dozens of roadside landslides, yet there is little evidence that budget demonstrate systematic risk-based prioritization: distinguishing which slopes are critically unstable, which pose high economic risk, and which can be managed through low-cost preventive measures. Without such differentiation, resources are spread thinly or deployed only after failure occurs.
An integrated approach to maintenance
International experience shows this cycle can be broken. Transportation agencies facing recurrent slope failures have adopted systematic slope management systems that integrate inventories, inspection schedules, condition databases, and predictive analysis.
Nepal’s own research on Himalayan highways points in the same direction. Combining pavement condition data with slope-failure susceptibility mapping using GIS allows smarter maintenance prioritization, by both functional importance and failure risk.
Four practical steps stand out.
First, treat slopes as assets. Every retaining wall, drainage structure, rockfall barrier, and check dam should be inventoried and tracked, just like bridges. Nepal already has technical guidance, including the DoR’s Guide to Road Slope Protection Works (2003), but these recommendations remain largely absent from routine maintenance.
Second, inspect systematically. Maintenance contracts should require regular slope inspections using standard checklists, enabling early detection of warning signs such as cracking, seepage, deformation, and drainage blockage.
Third, budget for prevention. Slope work should no longer be buried under “emergency maintenance.” Routine budgets must explicitly fund mesh repair, bolt tightening or replacement, vegetation management, erosion control, and minor stabilization work. Evidence consistently shows that every rupee spent on prevention saves several rupees in future repair and closure-related losses, especially in mountain highways where closure costs dominate.
Finally, the integrated system is a must. Pavement and slopes are managed by the same agency yet treated as separate problems. Integrated planning improves technical outcomes and makes better use of limited public resources.
Beyond pavement
The sharp escalation in 2081 BS should be treated as a warning, not as anomaly. Climate change is intensifying rainfall extremes, increasing the likelihood that small maintenance defects will turn into major failures. In mountain highways, pavement is merely the visible surface. Slopes are the foundation.
Until Nepal’s maintenance philosophy reflects that reality, roadside landslides will continue to surprise us, though the warning signs have been clear all along.
Beyond preparedness: Why Nepal must fund road resilience
This year, unlike in the past, the Government of Nepal’s prudence was evident when the Department of Hydrology and Meteorology (DHM) issued heavy rainfall warnings. The National Disaster Risk Reduction and Management Authority (NDRRMA) issued a four-day travel advisory for October 3–6, which prohibited long-distance vehicle operations and limited travel in susceptible areas. Citizens were urged to refrain from avoidable travel with early warnings of landslides and swelling rivers in the provinces of Koshi, Bagmati, Gandaki and Lumbini. Even public holidays were issued for two days, prompting the residents to stay safely at home.
With swift evacuations and well-coordinated communication, these preventative measures helped prevent significant losses during the monsoon. A slight improvement in Nepal’s disaster management was visible this year, evident with better early warning systems, institutional coordination and a maturing public response mechanism. Yet, early preparedness and rapid post-disaster recovery can no longer remain the only answer: infrastructures built for a gentler historical climate remain worryingly defenseless to the “new normal” of intensifying future extremes.
The flood that rewrote the map
The September 2024 floods were a sobering lesson. A rare cyclonic circulation and mid-tropospheric westerly trough triggered 60 hours of continuous rainfall across central and eastern Nepal. According to the Department of Hydrology and Meteorology, over 183 weather stations recorded more than 50 mm, while 25 broke 24-hour records, some exceeding 400 mm. The streams of the Bagmati, Koshi, and Narayani basins surpassed their historic highs, causing landslides, debris flows, and flash floods that affected 2.6m people, claimed 249 lives, and caused economic losses exceeding Rs 46bn, over one percent of GDP.
Among the worst hit was the Banepa–Bardibas (BP) Highway, a lifeline connecting Kathmandu with the eastern Tarai. Field assessments along the Roshi Khola corridor, from Bhakunde Besi to the Sunkoshi confluence, revealed widespread destruction, with dozens of landslides and slope failures damaging approximately 80 km of the highway, and 26 km were severely impacted. Collapsed retaining walls and eroded embankments were anything but sparse. In one particularly devastated stretch of the Kavrepalanchok district, the river eroded an 8-km segment of the roadway, rendering it impassable.
Our study found that the Roshi basin received an average of 267 mm of rainfall in 24 hours, equivalent to a once-in-773-year event, based on 60 years of rainfall records. The unprecedented precipitation turned the river into a force that the infrastructure was never built to face, with a discharge significantly higher than the design capacity.
A year later, the same story
The susceptibility was exposed again this year. Temporary repairs failed, embankments slumped and diversions were washed out. The BP Highway’s recurring damage reveals a systemic flaw: Nepal’s highways, particularly along river corridors, are no longer safe, acutely exposed to the whims of climate extremities.
Lessons from collapse
First, our engineering standards must evolve. The flood magnitudes adopted by the NRS 2070 assume a 50-year return period for first-class roads and a 100-year for bridges. While a 10 percent increase in design discharge is mandated to account for climate change, DOR’s Guidelines on Hydrologic and Hydraulic Analysis and River Training Works for Bridge Design no longer suffices in the face of rapidly shortening return periods.
There should be no delay in increasing the design return period to 100 and 200 years for major roads and bridges, respectively. Moving beyond reliance on historical data-based frequency analysis, all major road retrofitting, bridge reconstruction and new construction projects must be checked against the contemporary climate projections for the design period.
Second, planning must be risk-informed and data-driven. Integrating climate-informed vulnerability mapping to identify at-risk zones before the construction or repair is imperative. This helps to avoid the high-risk zones from the get-go and minimizes the likelihood of recurring future damage.
In flood-prone river corridors, vulnerability mapping determines where infrastructure elevation is necessary versus where an early warning system might suffice (reducing consequence through evacuation and traffic management). This systematic approach should be an indispensable first step before deploying costly engineering solutions.
And most importantly, resilience cannot rely on concrete alone. Structural adaptations like increased freeboard of bridges and strategic elevation of roadways should be complemented with nature-based and hybrid solutions, vegetative slope stabilization and bioengineering. In Nepal, steep slopes could benefit particularly from hybrid approaches such as vegetative bioengineering combined with check dams. Also, land-use planning, like establishing conservation buffer zones adjacent to floodplains to regulate development, prevents encroachments that heighten flood levels or exacerbate erosion.
Reaction to resilience
To break free from the disaster and repair loop, Nepal must embed “climate logic” into its development DNA. “Fund Resilience, Not Disasters,” the theme from the recent International Day for Disaster Risk Reduction, captures this urgency: invest now, or pay exponentially later.
Short-term restoration of strategically important corridors like the BP Highway must go concurrently with long-term resilience planning. Roads should be realigned away from unstable river bends where possible, with major corridors upgraded for at least 100-year floods, and slope protection integrated with river training works such as spurs and check structures.
Design standards must evolve beyond the historical averages to incorporate the plausible future scenarios. Climate risk screening and cost-benefit justification for resilience measures should be mandatory for detailed project reports. Increasing hydrometeorological networks and interleaving vulnerability mapping into road asset management will help prioritize investment where it matters most.
While these reforms seem costly, prevention is the cheapest insurance. Global evidence shows that every dollar spent on resilience saves at least four are saved in recovery. For Nepal, with annual road repair costs already exceeding Rs 3 billion, the choice is obvious.
The road ahead
While decisive early action can be effective in minimizing risks, it cannot substitute for durable infrastructure. Preparedness can save lives, but only resilience saves livelihoods.
The BP Highway disaster is more than just a damaged road; it serves as a warning. The next storm is imminent. Safeguarding every trip, whether to school, the market, or home, requires investing in resilience now, not in repairs later.
(Rajan KC is a civil/geotechnical engineer working on disaster mitigation and resilient infrastructure.)
