An account is given of the use of Road Weather Information Stations (RWIS) in Idaho, US to provide accurate information and cost savings on winter maintenance. The Idaho Transportation Department (ITD) invested $5 million in a system to cover its 930 miles of road in areas which vary from desert to mountain summits. RWIS sites collect atmospheric data including temperature, humidity, dew point, wind velocity and direction, atmospheric pressure, precipitation type and amount, and visibility distance. Most RWISsites have at least one CCTV camera for generating snapshot images of theroadway. In terms of winter maintenance operations, pavement sensors or Vaisala's non-invasive technology measure the temperature of the pavement,the thickness of any ice build-up and the friction coefficient of the surface. The system has helped ITD in assessing when and how much material toapply with more accuracy than the early morning routine storm patrols were able to. Gritting can be carried out ahead of storms and blends modified. It is estimated that savings of at least 25 per cent in materials havebeen achieved.
Abstract