Optical roadstate monitoring for infrastructure-side co-operative traffic safety systems

This paper describes the preliminary results for detecting slippery road conditions. The detector will be implemented in a larger system intended to increase the safety margin for vehicle drivers, by utilising so-called co-operative driving where infrastructure to vehicle communications operate seamlessly. The ice detection system is based on intensity differences in reflectance for horizontal and vertical polarisation planes. The results show that relative light reflection in the horizontal plane compared to the vertical plane is 59% higher in the case of ice than for dry asphalt. Furthermore, the detector includes a so-called graininess analysis, which provided a 32% reduction in granularity when moving from dry asphalt to ice. Combining these two methods enables a robust and reliable ice/wet road detection application. This paper also briefly describes how the ice detection application can be connected to the overall safespot safety system, its particular relevance and its planned implementation on the test sites.