Updating Secondary Climate Attributes for Transportation Infrastructure Management

Abstract

With research studies continuing to provide strong evidence that climatic conditions significantly impair the physical condition and longevity of civil engineering infrastructure, the importance of reliable climate data cannot be overemphasized. Climate considerations play a critical role in infrastructure deterioration prediction, attribution of infrastructure repair responsibilities across the load and nonload factors of deterioration (for cost allocation purposes), and numerous other agency functions involving infrastructure planning, design, operations, monitoring, and repair. Often, for such applications, the secondary indicators of climate, primarily the freeze index and freeze-thaw cycles, are of particular interest. Unfortunately, at the current time, data on the secondary climate attributes stored in existing infrastructure-related climate databases are either outdated or exist in the form of highly aggregate qualitative characterizations such as climate zones or regions. The impact of these limitations becomes even more salient when viewed against the backdrop of incipient long-term climate change and the variability of climate conditions within each climate zone. To address these limitations, this paper uses data from the contiguous United States to first examine the temporal changes in primary climate attributes using the climate normals from two overlapping time windows. ANOVA and Tukey multiple comparison procedures are applied to investigate whether there have been statistically significant changes in climate attribute levels across the two time windows and magnitude of any such changes. The results show that over the study period under consideration, states in the Northern and Rocky Mountain regions particularly experienced significant changes in their secondary climate attributes. Furthermore, the paper provides updated values for the two secondary climate attributes that are of particular interest to infrastructure engineers. To determine these attributes, interpolation methods in a geographic information system (GIS) are used to develop isarithmic maps of the climate attributes to facilitate their interpretation and application. In summary, this paper provides an improved and updated characterization of climate conditions in the contiguous United States and makes location-specific secondary climate attributes available to infrastructure engineers and managers for use in their various agency functions.