Global weather specialist Vaisala has launched a newly developed non-invasive road weather information system with substantial benefits for road operators. The Guardian Road Weather Information System (RWIS) uses laser spectroscopy to gauge pavement condition during all types of weather. It measures a variety of parameters: amount of accumulated water, frost, ice, slush, snow, and humidity as well as air and pavement temperature. For the first time ever for non-contact sensors, Guardian also derives a measu