Cold snowy regions are typified by the occurrence of traffic accidents due to poor visibility in snowstorms. In severe snowstorms, drivers are guided by whatever remains visible, such as road accessories. Therefore, it can be said that visual guides play a significant role in supporting safe driving in winter. From 1996 to 1998, it was studied how such visual guides, called "self-emitting delineators", can function best in cold snowy regions against the background snow with various degrees of brightness. The brightness judged to be optimal by the driver changes according to the range of visibility and background brightness (environmental illumination). A field experiment was conducted in 1999. Self-emitting delineators were installed to evaluate how well the delineators could be seen and to analyse the driver's eye movement by "eye camera". It became clear that guiding drivers' eyes with optimal brightness was effective in stabilising their eye movement. Based on those results, a visual guidance system was created, whereby the relevant facilities are controlled according to environmental conditions of the site. Brightness of the self-emitting delineator changes automatically to secure the best possible visibility in accordance with environmental conditions as sensed by meteorological instruments. At the same time, the content and brightness of variable message boards change automatically, to guide drivers effectively. The system was introduced on an experimental basis: Road administrators are able to check and monitor the weather data, the functioning of relevant facilities, and the on-site images taken by closed-circuit TV (CCTV) camera by Internet.
Abstract