Assessing Highway Bridge Chloride Exposure at a Provincial Scale: Mapping and Projecting Impacts of Climate Change

Abstract

This study addresses the absence of a provincial scale database on chloride exposure for bridges, which specifically focuses on Ontario, Canada. Considering the region-based climate and traffic characteristics, a comprehensive database was developed based on chloride exposure prediction models. This database documents chloride exposure information under different Representative Concentration Pathways (RCPs) of greenhouse gas (GHG) emissions for bridge piers and decks across regions and times. This prediction model was validated against experimentally derived chloride profiles from concrete core samples. The database allows for the assessment of spatial and temporal patterns in chloride exposure, which considers the projected climate change conditions. To facilitate data interpretation, this study employs heat maps to transform the extensive provincial database into a visually accessible format. Bridge piers in Southern Ontario have higher surface chloride concentrations than those in Northern Ontario; however, bridge decks in Northern Ontario tend to exhibit higher surface chloride concentrations compared with those in Southern Ontario. Future projections suggest an overall increase in the surface chloride concentrations on bridge piers across most of Ontario under the RCP4.5 and RCP8.5 scenarios, which is largely attributed to increased traffic volume. However, certain southern regions might see a decrease under RCP8.5, which is a direct consequence of climate change. In contrast, surface chloride concentrations on bridge decks are expected to decline, a trend that is driven by diminishing snowfall and increasing traffic volume. In addition, these findings suggest that relying on RCP8.5 could lead to underestimating the climate change impacts compared with RCP4.5. This study highlighted the spatiotemporal patterns in highway bridge chloride exposure in the context of climate change.