Phase 1: Have Minnesota's Warmer Winters Increased the Number of Freeze Thaw Cycles?

Status:  Complete
Report Date:  09/29/2022

Summary:

Minnesota’s winters are among the fastest warming in the U.S. This warming trend is likely increasing the time in which winter temperatures are near freezing, which could increase the number of freeze-thaw events and could have detrimental effects on Minnesota’s pavement systems. When water seeps into pavement and then freezes and thaws, cracks and potholes can occur. The more freeze-thaw cycles there are over a winter season, the more damage to pavement. While MnDOT suspected the warming winters are increasing the number of freeze-thaw events that impact the state’s roads, recent research illustrated this isn’t the case. A comprehensive analysis of several historical environmental databases, including temperatures and moisture levels in pavement and the subsurface, improved understanding of the state’s changing climate. This allowed researchers to quantify the trends in freeze-thaw cycles in pavement at the MnROAD testing facility. They found that at shallower pavement depths, these cycles are decreasing in early and late winter, and no trend was observed for the remainder of the winter and at deeper layers in the pavement and subsurface. The research team also found, however, that precipitation has increased in early and late winter, which may increase pavement damage. They continue to analyze the relationship between environmental conditions and pavement damage, and will provide MnDOT with practical knowledge and tools to manage sustainable pavement as the climate changes.

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