Mapping Roadway Freezing and Thawing using the Applied Climate Information System

In seasonal frost areas, as freezing occurs roads become stiffer and stronger. Many state departments of transportation take advantage of the period of higher strength in mid-winter by applying winter weight premiums (WWPs), increasing the allowable weight that trucks can haul. During late winter and early spring when the top road layers begin thawing and can’t drain excess water, the road is highly susceptible to damage. To reduce roadway damage, many highway agencies apply spring load restrictions (SLR) during the critical time interval when the pavement is most vulnerable to damage. Using a 4km gridded temperature product developed at the Northeast Regional Climate Center and available through the Applied Climate Information System, cumulative freezing and thawing indices are calculated and mapped. Freezing and thawing indices are also computed using 6-day forecasts from the gridded National Digital Forecast Database, providing state transportation departments in Main and New Hamsphire ample lead time to implement WWPs and SLR.

In this talk we will discuss the creation and operational updating of the gridded dataset, the procedure for computing freezing and thawing indices, and the creation of statewide maps that highlight areas where WLR and SLR are indicated.