Different types of sensors developed for tracking road conditions were installed at the Ishikari Blizzard Test Station, Japan, to investigate their use in advanced cruise-assist highway systems on winter roads, their effectiveness in accident prevention and their acceptance by users. Image data from the visible-light image methods and the infrared image method concerning moving vehicles and pedestrians under conditions of snow cover and falling snow were recorded on videotape. Data on detection by the milliwave method were also recorded by a data storage device. The detection results of the moving vehicle and pedestrian were evaluated for four different ranges of visibility. Under conditions of blowing snow with a range of visibility under 1000m, detection of moving vehicles by the visible light sensor was significantly affected, especially for white vehicles. Stationary vehicles were detected at 500m visibility but not at 200m visibility. Pedestrians were less well detected because of their smaller size than cars. Pedestrians wearing white clothing were particularly hard to detect. Using infrared imaging, the moving car could be detected at 100m at 200m visibility in blowing snow. Stationary vehicles were detectable at visibilities greater than 200m and pedestrians at about 200m. The milliwave method gave best results at under 200m. Field tests on actual roads are planned.
Abstract