The ATO green roads profiles present country-level perspectives on how 35 Asia-Pacific economies are addressing the development and management of sustainable eco-friendly roads. Drawing from diverse datasets and policy documents, the profiles highlight practices and measures that contribute to greener transport infrastructure.

Developed by the Asian Transport Observatory (ATO) in partnership with the International Road Federation (IRF), the profiles are designed to complement the Green Roads Toolkit. The toolkit provides a practical reference for integrating good practices across nine dimensions:

• Decarbonization
• Climate resilience
• Water and land management
• Pollution reduction
• Conserving biodiversity
• Responsible sourcing of materials
• Improving quality of life
• Disaster preparedness
• Fostering inclusive growth

This 2025 edition builds on earlier work to provide a comprehensive resource for guiding the planning, development, construction, and management of greener, more sustainable roads.

Tonga's transportation system is characterized by a dense network of local roads rather than expansive motorways. Covering about 720 square kilometers, the country's 1,200 kilometers of roads lack any motorways or main highways. Instead, 94% of these roads are local and rural, resulting in a density of 1,727 meters per square kilometer. This infrastructure setup creates a paradox: although the physical network is compact, the environmental and economic impacts are growing quickly, highlighting the need for "Green Roads" that focus on resilience and reducing carbon emissions rather than just expansion.

The urgency for this transition is driven by a decoupling of transport emissions from broader economic trends. Since 2000, road transport greenhouse gas (GHG) emissions in Tonga have grown by 4.2% annually, significantly outpacing the economy-wide emissions growth of 1.4% per year. By 2024, road transport accounted for 86% of total transport emissions and nearly a quarter of the nation's entire GHG inventory. More concerning for policymakers is the efficiency trajectory; while the Asia-Pacific region improved its emissions intensity by 5.4% annually since 2015, Tonga's intensity remained largely stagnant, improving by only 0.2%. With an emissions intensity of 86 grams of CO2e per USD—more than triple the Asia-Pacific average of 26—the sector remains heavily carbon-intensive.

Underpinning these emissions is a fleet composition that suggests a clear pathway for electrification, provided market barriers can be overcome. The road network is dominated by two-wheelers (52%) and light-duty vehicles (33%), with buses constituting only 1%. Despite this favourable profile for electric mobility, market penetration remains negligible. Between 2015 and 2024, the value of electric vehicle imports totalled just 258 thousand USD, representing less than 1% of total road vehicle imports in 2024. The UNEP E-mobility Readiness Index scores Tonga at 58 out of 100, highlighting a stark disparity: while policy and energy readiness score a moderate 20, technology and market readiness lag significantly at just 5.

Beyond mitigation, the "Green Roads" agenda in Tonga is existentially linked to climate adaptation and infrastructure resilience. The country ranks 175th out of 208 nations in the National Road Vulnerability Index, reflecting a system where the loss of key segments to natural hazards can lead to catastrophic connectivity failures. Since 2000, the country has weathered 12 recorded natural disasters—primarily storms (75%)—affecting 225,000 people and costing nearly $400,000.

The economic toll of this vulnerability is chronic. Tonga faces estimated average annual losses of 530.7 thousand USD to transport infrastructure, roughly 0.065% of GDP, with 61% of these losses related specifically to roads. Bridges are disproportionately exposed; despite accounting for a negligible fraction of the infrastructure stock, they bear 10.5% of the road sector's financial losses. Furthermore, material flows indicate an annual requirement of 144 thousand tonnes of material for expansion and maintenance, embodying 4 thousand tonnes of CO2-equivalent emissions, further linking physical resilience with the carbon cycle.

The human cost of the current transport system reinforces the need for reform. Congestion accounts for 62% of the externalities associated with fuel subsidies, while road crashes account for 38%. Air pollution presents a silent economic burden; the World Bank estimates the annual cost of health damages from PM 2.5 exposure at 31 million USD, or about 5% of GDP. Although road transport contributes only 20% of the sector's PM 2.5 emissions, the concentration of these emissions in populated areas exacerbates the health impact.

Social inclusion remains the final pillar of the Green Roads framework. Currently, 3,000 rural residents live beyond the reach of all-season roads, isolating them from essential services and slowing disaster recovery. Access to urban centers is equally constrained, with nearly 100% of the population requiring more than 30 minutes to reach cities. Furthermore, the sector shows gender disparities, with women comprising only 28.9% of the transport workforce.

Achieving a sustainable transport future in Tonga requires navigating a complex interplay of high motorization rates—491 vehicles per thousand population—and fragile infrastructure. The data indicates that a "Business as Usual" approach will result in escalating maintenance costs, rising emissions intensity, and continued vulnerability to climate shocks.

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