Each year, many state Departments of Transportation (DOTs) struggle to maintain safe roadways during the winter season. Winter weather can present extremely hazardous driving conditions, especially in an area of varying weather patterns and mountainous terrain, such as New England. In order to thoroughly treat roadways, DOT engineers and maintenance workers rely on accurate forecasts to assist in the decision-making process. The timing and onset of winter storms is crucial when making a critical decision. Efficient use of a local weather data and accurate forecasts will benefit DOTs and help reduce the cost of materials, equipment and man-power. The New Hampshire State Department of Transportation (NHDOT) and Plymouth State University (PSU) have recently purchased 12 weather stations that have become New Hampshire's first Road Weather Information System (RWIS) network.

The NHDOT has already incorporated RWIS into their 2006-2007 winter maintenance season and have found the system's accuracy to be inconsistent. In order to determine the true accuracy and reliability of the RWIS system, the atmospheric and pavement data has been verified and comparisons have been made with surrounding ASOS/AWOS data during this past winter season (October 2006-April 2007). RWIS data has been analyzed for errors and biases and some winter season case studies have been conducted to show how the system can be more efficient in an effort to improve maintenance operations and address challenges the NHDOT experiences.

Although the data from each RWIS station corresponds to one specific point at the surface, practical deductions and educated assumptions based on the data can be applied to the surrounding areas where RWIS stations do not exist. Understanding the physical placement of each RWIS station, as well as the strengths and weaknesses of the system will enable NHDOT be better prepared during future winter seasons in New Hampshire.