Road Infrastructure and Climate Change: Risks, Impacts and Adaptation Strategies
- zoumalou
- 7 hours ago
- 6 min read
A road is often seen as an immutable piece of infrastructure, nothing more than an inert strip of asphalt. Yet, as it is sometimes described by Routes de France, the national association representing French road operators and contractors, roads are "the country’s first social network". They carry most economic flows, enable everyday mobility and provide critical access for emergency services.
Unlike power grids or rail networks, which are more centralized and closely monitored, road networks are managed by a wide variety of actors and are directly exposed to natural elements. Roads are everywhere, crossing forests, mountains, coastal areas and dense urban environments. This ubiquity, which is essential to their role, make them extremely vulnerable as climate risks intensify in both frequency and severity.
The challenge goes far beyond road engineering alone. Losing a road corridor can isolate entire communities, disrupt economic activity and prevent the delivery of essential goods and services. Adapting road infrastructure is therefore not only a technical issue, but a core requirement for collective resilience and long term infrastructure adaptation.
This article is based on a webinar organized in January 2026 with Pierre Monlucq, Chair of the Foresight Commission at Routes de France, and François Dorey, project manager for infrastructure resilience at SETEC. The replay is available here (in French)
A vast yet overlooked road asset
France has one of the densest road networks in the world. This asset, estimated at around 1,100,000 kilometers of roads, represents a major source of economic and social value. It is also a significant management challenge, due to the fragmentation of responsibilities across multiple organization and public authorities.
The breakdown of this network illustrates the scale of the issue:
20,000 km of major strategic corridors, including 10,000 km of privately operated motorways and 10,000 km of national roads managed by the State.
380,000 km of departmental roads.
700,000 km of municipal and urban roads.
Experts paint a worrying picture. While the strategic network, national roads and motorways, is generally well monitored, more than 50 percent of the total road asset is not formally assessed. In practice, the condition of half of French roads is simply unknown. For this part of the network, mainly local and municipal roads, issues are identified only once damage becomes visible.
This lack of knowledge feeds what road professionals refer to as the "gray debt": an invisible accumulation of deferred maintenance. Too often, action is taken only when potholes appear or when structural failures occur, even though preventive maintenance would have been far less costly and far more effective.
Roads facing climate risks: real world examples
The impact of climate change on roads is no longer a theoretical projection. It is now an operational reality, documented through recent major damage events. The case of National Road 134 in southern France is particularly illustrative. Following intense rainfall in the Aspe Valley on already saturated soils, an entire section of mountainside collapsed, taking the road with it. Extensive reconstruction works followed over a three month period, effectively choking cross border economic activity between France and Spain in the area.
Floods in the Pas de Calais region in 2023 and 2024 marked another major wake up call. With rainfall locally reaching up to 1.5 times the historical one hundred year level, around 500.000 residents were affected and the economic cost ran into several billion euros. Engineers observed a sharp increase in the frequency of so called rare events. In some locations, what was once considered a ten year flood can now occur three times within a single year, making the design assumptions used for road structures and hydraulic works increasingly obsolete.
"To design infrastructure, there must be agreement on foreseeable risk levels. But today, a ten year storm can happen three times a year. Our statistical reference frameworks have been profoundly disrupted." Pierre Monlucq - Chair of the Foresight Commission at Routes de France
The impact of climate change on French roads: a simple risk mapping
Historically, climate related hazards tended to be confined to specific regions. Wildfires were mainly associated with the southeast or France, while flooding was expected in well identified flood prone areas. Climate change is now reshaping this geographical distribution of risks, exposing road infrastructure to new combinations of hazards across the entire territory.
Type of hazard | Impact on road infrastructure | Observed trend |
Extreme heat | Softening of asphalt, rutting, accelerated pavement aging | Now affecting the entire country |
Flooding | Failure of embankments, saturation of drainage systems | Expanding northward and eastward, with more intense events |
Drought and soil shrink swell | Longitudinal cracking, pavement deformation | Now impacting clay rich areas previously unaffected |
Wildfires | Destruction of signage, post fire soil destabilization | Spreading toward central and northern France (e.g.: Brittany, Vosges...) |
Coastal submersion | Erosion of coastal road foundations, salt corrosion | An increasing threat for coastal roads and overseas territories |
France’s overseas departments and territories often act as early warning systems for these dynamics. They combine exposure to intense cyclonic risks, accelerated coastal erosion, as observed in Saint Pierre and Miquelon, and specific challenges linked to tropical soils, particularly in French Guiana.
When asphalt overheats: a material impact of warming on roads
Rising average temperatures, projected to reach +2.7°C by 2050 under France’s reference pathway for climate change adaptation, have direct physical effects on road materials. The primary phenomenon is the softening of asphalt pavements. Under the combined effects of heat and traffic loads, especially heavy trucks, the pavement begins to deform, creating ruts. Beyond discomfort for drivers, these deformations become hazardous during rainfall, as they trap water and significantly increase the risk of hydroplaning.
In Marseille, road surface temperatures can already reach 80°C during summer heatwaves. Climate projections suggest that peaks of 90°C could occur within the next 20 years. At such temperatures, the rheological properties of bituminous binders are altered, leading to irreversible pavement deformations.
At the same time, repeated cycles of extreme heat accelerate oxidation and aging processes in asphalt binders. A road designed for restauration every 15 year may see its lifespan reduced to 10 or 12 years, fundamentally disrupting maintenance strategies and asset depreciation plans.
Another critical issue concerns road equipment and ancillary infrastructure. Horizontal road markings, which are essential for traffic safety and future autonomous vehicles, degrade more rapidly under intense heat and ultraviolet radiation. Hydraulic drainage systems, including culverts and roadside ditches, were designed based on 20th century rainfall patterns. Faced with today’s intense cloudburst events, they are increasingly undersized, turning roads into temporary torrents during extreme rainfall.
A toolbox of solutions for climate resilient roads
In response to these challenges, the road industry and engineering community already have access to proven technical solutions. The key issue today is no longer innovation alone, but large scale deployment.
1. Water management and iSWM approaches
The prevailing approach is shifting away from a "everything go in the tipe" logic, where water is evacuated as quickly as possible, toward Integrated Stormwater Management (iSWM). The objective is to infiltrate rainfall as close as possible to where it falls.
Solutions include vegetated swales, infiltration trenches and, most importantly, reservoir pavements. These porous structures, with up to thirty percent void space, can temporarily store stormwater within the pavement layers before slowly releasing it into the soil or downstream networks. This approach helps prevent the saturation of drainage systems during intense rainfall events.
2. Adapting road materials
To address urban heat islands and asphalt softening, several strategies are already being implemented.
Light colored and reflective surface treatments: Applying lime based or light colored binders increases road albedo and can reduce surface temperatures by several degrees.
Permeable and draining asphalt mixes: These surfaces prevent the formation of a water film, reduce spray and contribute to cooling through evaporation.
Bio based and recycled materials: These materials are designed to deliver mechanical performance comparable to conventional solutions while significantly reducing the carbon footprint of road construction.
Unlike conventional impermeable roads, reservoir pavements are built using highly porous materials. With around thirty percent void space in their internal structure, they act like a giant sponge, capable of absorbing intense rainfall events almost instantly. Water is stored beneath the running surface and then gradually released into the ground or drainage network. This provides a multiple benefit: improved road safety, with no standing water on the surface, and more resilient urban stormwater management.
3. Diagnose and prevent the shift toward preventive maintenance
The most cost effective solution remains preventive maintenance. Simple techniques such as crack sealing, which involves treating early stage pavement cracks, prevent water from penetrating the structure and causing further damage. This low cost intervention can significantly extend the service life of road assets.
These solutions clearly illustrate the "cost of non-adaptation". Failing to implement relatively simple and affordable measures today may lead to much heavier and more expensive reconstruction works in the future.
Waiting is a losing strategy when aging infrastructure is confronted with increasingly severe climate hazards. Fortunately, France’s National Climate Change Adaptation Plan together with the TRACC, the new reference scenario for adaptation, provides incentives and a clearer regulatory framework for infrastructure adaptation.
Adapting road infrastructure is a massive technical undertaking. Above all, it is an investment in civil safety and economic continuity at the national scale. And the solutions already exist.
For networks as extensive as road infrastructure, diagnosis and prioritization are the cornerstones of any effective adaptation strategy. By combining scientific expertise with Callendar’s tools, infrastructure managers now have an operational solution to anticipate how climate risks will evolve across their assets and networks, assess impacts on infrastructure and operations, and implement concrete and prioritized adaptation measures.
Are your infrastructure and industrial sites ready for today’s and tomorrow’s climate? Contact us to carry out a climate risk assessment and secure your projects starting today.