Impact of Wildfires on Pavement Systems

Abstract: The United States has seen a recent steady increase in the intensity and size of wildfires, especially in the Western states. This is largely attributed to the impacts of climate change, which is greatly altering historical wildfire patterns by creating warmer, drier conditions and by prolonging the fire season. Wildfires can have devastating impacts on roadways, both directly and indirectly. Direct impacts include physical damage caused by flames and heat to the pavement surface and other ancillary assets (e.g., culverts) and associated reductions in mobility and accessibility, while indirect impacts can include erosion, settlement, slope instability, structural damage to the pavement structure due to post-fire flooding and debris flow, and the damage caused due to debris hauling and other response and recovery efforts. With respect to pavement systems, wildfires can potentially affect their serviceability in any or all of the following ways:

- Surface damage during the fire event itself, which could lead to melted pavement, potholes, raveling, and delamination.
- Structural damage to the pavement as a result of the increase in both the number and weight of the traffic loadings from detoured traffic, fire suppression vehicles, and post-fire cleanup operations.
- Potential damage due to post-fire flooding (e.g., complete washout and debris flow, loss of structural capacity due to inundated base layer).
- Damage to pavements due to clogged or damaged drainage systems (e.g., inundated base layer, standing water on pavement surface).
- Shortened pavement life from the above factors and possible premature aging of the asphalt binder in the pavement surface layer (where exposed to elevated temperatures from the wildfire).

This presentation will summarize the existing body of knowledge on impacts of wildfires on pavement systems while also identifying gaps and key research needs. Lessons learned from highway agency experiences in managing wildfire impacts will also be discussed. Specific actions that can be taken by highway agencies today to improve the resilience of pavement systems to wildfire events will be highlighted. Other topics that will be covered in the presentation include post-fire pavement condition evaluation methods, impact of response and recovery activities, and approaches to repair and rehabilitate damaged pavements.