An Analysis of Variability Between RWIS Road and Air Temperature Observations

Road condition modeling is a challenging task that requires a deep understanding of road physics and its interaction with the atmosphere. A traditional approach to road condition forecasting has been to simply use atmospheric conditions to determine the type and quantity of accumulation on the road surface.  This analysis aims to quantify the errors associated with mapping air temperature directly to the road surface. To accomplish this, observed road surface temperature from Road Weather Information Systems (RWIS) are compared to the observed air temperature from the same site.  Initial investigations focus on 30 RWIS sensors from Iowa, as they are well maintained and are located along representative road segments.  Data are sampled from the winter months to best illustrate the errors during important phase changes.