Impacts of climatic change and variability on winter-road maintenance in North America

This study links the fields of applied climatology and transportation geography. Important climate variables and threshold values that are related to winter-road maintenance activities are used to derive trends spatially and temporally across all of North America. Historical climate data for the period of 1948--49 through 2003--04 winter seasons are used. The study introduces the concept of a response surface to view climate conditions with jointly-changing mean and variance with respect to the near-zero temperature (NZT) range. It also examines the conditional probability of snowfall events and mean air temperature. An additional analysis is carried out for the duration of spring thaw, which is a critical time period for highway pavement.; Changing values of mean air temperature and its relationship with respect to the NZT range reveal a complex behavior in Potential Hazard Days (PHD, the number of days falling within the NZT range). Many climate stations in the Pacific Northwest exhibit negative trends in PHD, while those stations in the High Plains and Canadian Prairies show positive trends in PHD. These contrasting trends are induced by positive trends in the minimum air temperature, and thus it illustrates a complex relationship surrounding the mean and its behavior. The examination of severity and duration of the winter season shows that they are not necessarily correlated and have different impacts for the timing and duration of spring-thaw.; A series of exploratory analyses identify potential regions where winter-road maintenance activities will likely be modified due to changing climate. Any change in the magnitude or frequency of snowfall events within a certain temperature range will have significant impacts on the type, magnitude, frequency, and timing of winter-road maintenance activities. The response surface and conditional probability of snowfall events provide additional tools for highway engineers and policy makers to assess their current practices under the conditions that changing climate will bring.