As mountain cities grapple with congestion, climate risks, and eco-sensitive geographies, conventional mobility solutions often prove inadequate. There is an urgent need for innovative, context-sensitive strategies to build equitable and ecologically resilient transport systems.
The recent flash floods that wreaked havoc in the Uttarkashi district of Uttarakhand are a glaring reminder of the deeper crisis that the rapid pace and scale of unplanned urbanisation bring to the eco-sensitive geographies of the mountains. Urbanisation in mountain regions is shaped by multiple and interlinked factors, including natural population growth, in-migration from rural settlements, acute land constraints, and, in several cases, increasing tourism. The resulting expansion often spills over into ecologically vulnerable zones such as steep slopes and flood-prone areas, increasing exposure to landslides, earthquakes, water scarcity, and other socioecological challenges. Today, more than half of the world’s population lives in cities, a figure expected to rise rapidly to 68 percent by 2050. This urban expansion strains the already fragile ecosystems and the delivery of basic services.
Today, many mountain cities are exceeding their ecological and infrastructural carrying capacities as unregulated urban sprawl and seasonal tourist booms lead to severe congestion, straining basic services and causing environmental degradation. Climate change intensifies these risks with extreme weather events coinciding with terrain and infrastructural precariousness. Mountain cities are more prone to landslides and air pollution, and are situated on tectonic plate boundaries, making them high seismic zones. Overlooking these concerns can lead to ecosystem collapse, economic stagnation during disasters, and the fraying of the social fabric. The question is, what happens when cities once built for only a few thousand people now host millions, perched on unstable mountain slopes?
The question is, what happens when cities once built for only a few thousand people now host millions, perched on unstable mountain slopes?
For the long-term sustainability and resilience of mountain cities, policymakers must move beyond one-size-fits-all urban solutions. Instead, adopting context-specific and terrain-sensitive mobility infrastructures informed by indigenous knowledge and local ecological wisdom can serve as a good starting point.
In mountain cities, traffic congestion is a key driver of the climate and ecological crisis. Urban sprawl, tourism, and increased use of private vehicles create chronic gridlock in many spatially constrained Himalayan towns like Shimla, Manali, Gangtok, and Leh, especially since they have little room for expanding traditional road infrastructure. Yet, private vehicle numbers and road expansion projects continue to rise. Gasoline-powered vehicles emit greenhouse gas emissions (GHGs) at higher rates, accelerating global warming, worsening air quality, and polluting local water bodies, putting sensitive glaciers at risk.
Emissions from mountain cities have a greater impact on glaciers. Black carbon particles deposit on snow and glacier surfaces, accelerating glacier melt due to reduced albedo. Microplastics in glaciers add to this effect. About 30 percent of the observed glacier retreat in the Himalayas can be attributed to black carbon deposits. Irregular glacier melting results in the formation of glacial lakes with unstable moraine walls, increasing the risk of glacial lake outburst floods (GLOFs). The 2013 Kedarnath GLOF in Uttarakhand was triggered by extreme rainfall and glacial melt. More recently, the October 2023 Sikkim GLOF, considered one of Asia’s worst climate disasters, caused the collapse of a hydroelectric dam project (Teesta III).
Hill cutting and deforestation without sufficient geological assessment weaken mountain slopes, resulting in frequent and severe landslides.
Vehicular surge, road widening projects, and highway construction impact terrain stability, as seen in the Char Dham highway project. Hill cutting and deforestation without sufficient geological assessment weaken mountain slopes, resulting in frequent and severe landslides. The July 2025 building collapse in Shimla is a reminder of the environmental vulnerabilities of the region. Global warming-induced drought has also led to the displacement of the Samdzong village in the Nepal Himalayas.
These examples underscore the urgent need for mitigation and adaptation measures to prevent these cities from becoming uninhabitable in the coming decades.
Mountain cities require the integration of ecosystem-sensitive approaches to plan mobility systems that are low-impact and adaptable to steep gradients, fragile soils, and seismic risks. One compelling example is Mi Teleférico in La Paz, Bolivia — a pioneering urban ropeway transit system that demonstrates cost-effective, safe, and reliable urban transport — reducing wait times for travellers by 22 percent. However, in larger and administratively fragmented cities, such projects can face delays due to challenges in funding, land acquisition, and coordination — issues that the ongoing ropeway project in India’s Himachal Pradesh, stretching over 40 km between Shimla and Parwanoo, must avoid.
Santiago, Chile, where 4.2 million of its population of 7.3 million residents use public transport daily, has developed its metro line in just one year by sourcing cost-effective trains from China for US$260,000. Part funding for the project came from Santiago’s modern tolling system, which uses in-vehicle tags to facilitate faster passage for 4 million vehicles. The programme has not only been successful in stopping stop-and-go patterns at toll collection points, but has contributed funds to sustainable initiatives such as BikeSantiago, majority electric buses, and two long-term power purchase agreements with solar and wind developers for the metro’s electricity.
One compelling example is Mi Teleférico in La Paz, Bolivia — a pioneering urban ropeway transit system that demonstrates cost-effective, safe, and reliable urban transport — reducing wait times for travellers by 22 percent.
Sustainable technologies and investments must be supported by coherent policy frameworks. Planning models such as the PyP Solidario in Bogotá, Colombia, showcase how aggressive traffic policies, if implemented in stages, can eliminate vehicular congestion and support sustainable infrastructure. PyP’s first stage allowed vehicles with even or odd registration plates on the roads on alternate days of the week from 6 AM to 8 PM, encouraging private vehicle users who do not wish to buy exemption passes to ride earlier in the morning, thereby reducing congestion. These policy measures not only curb congestion but also provide a funding stream for sustainable mobility interventions.
Mountain stairways have historically functioned as essential pedestrian routes by connecting elevation levels and linking arterial roads. As seen in Norway’s Preikestolen and Medellín’s escalator-integrated stair systems, they also function as community spaces and tourist attractions, enhancing accessibility and footfall. These staircases, when well-designed, offer a low-impact, space-efficient alternative to road expansion, helping reduce vehicular dependence while preserving slope stability. Together, these examples show that sustainable mobility in mountain cities is not a binary choice between ecology and economy but a matter of designing mutually adaptable systems.
Mountain cities must draw from a combination of evidence-based policies, smart technologies, and ecological wisdom to ensure long-term resilience. Global examples demonstrate the effectiveness of traffic tolls and city-wide congestion pricing to support initial funding and generate resources for long-term sustainable transportation projects. These policies must be flexible, allowing for regular evaluations and adjustments based on real-time performance data. They should also focus on monitoring and penalising encroachments and regulatory bypasses that jeopardise the eco-sensitive mountain terrain. Mountain cities can combat congestion by building on existing smart technology. Traffic light controls and alarm systems equipped with video cameras and sensors on roads and bridges — to collect data on traffic conditions — are already being implemented in many cities. Sensor-based systems for real-time landslide detection, monitoring, and early warning must be used to alert local governments and communities about potential landslide events before surveyors detect them.
By integrating traditional knowledge systems with innovative urban design and smart technologies, mountain cities can lead the way in building resilient urban futures that are not only livable but also sustainable. The key to sustainability in mountain cities lies in embracing terrain-sensitive planning, inclusive governance, and a deep respect for the land they stand on.
Soma Sarkar is an Associate Fellow with the Urban Studies Programme at the Observer Research Foundation.
Tsering Lama was an Intern at the Observer Research Foundation.
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Soma Sarkar is an Associate Fellow with ORF’s Urban Studies Programme. Her research interests span the intersections of environment and development, urban studies, water governance, Water, ...
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