Abstract:
This study investigates the sensitivity of flexible pavement performance to both
historical and projected climate conditions across five Canadian cities over four 25-
year design cycles (2000–2099). Hourly climate inputs from MERRA2 and dynamically
downscaled CanRCM4 outputs under RCP 2.6, 4.5, and 8.5 were processed using the
Pavement Mechanistic-Empirical Design (PMED v3.21) tool. Climate projections were
stratified as maximum, median, and minimum ensemble members for each RCP to
account for the uncertainty. Five primary distress responses (total and asphalt
permanent deformation, bottom-up fatigue cracking, thermal cracking, and international roughness index) were simulated under each scenario and compared against historical baseline. Results reveal a significant increase in mean annual air temperature and precipitation, with pronounced reductions in freezing indices and freeze-thaw cycles, especially under high-emission RCP 8.5 scenario with maximum ensemble projection. Climate-driven increases in temperature substantially accelerate the rates of rutting and fatigue cracking, leading to premature loss of service life up to 66% in asphalt permanent deformation for the worst-case scenario (RCP 8.5 and 2075-2099 design period), while simultaneously reducing thermal cracking risks. The findings demonstrate marked regional variability, with the Prairie provinces being most
vulnerable due to climate change. The study underscores the inadequacy of relying on
historical climate data such as MERRA2 and emphasizes incorporating high-resolution region-specific climate projections with conservative RCP scenarios into pavement design protocols to ensure long-term infrastructure resilience in the era of climate change.