A GIS-based spatiotemporal analysis of the exposure to direct sun light on rural highways

Geographical Information System (GIS) technology integrates hardware, software and spatial data for capturing, storing, updating, managing, analyzing and displaying geographical data and phenomena. Spatiotemporal analysis of such phenomena is one of the major tasks of a GIS. In this paper, we use GIS for the modeling of the exposure to direct sun light in a rural road network. When a vehicle is moving towards the direction of the sun, drivers may experience temporary loss of vision. The main target is to build a system able to identify road sections at risk due to direct sun-light for a specific time period. The proposed methodology is based on the road network geometry, the relief of the study area under investigation (Digital Elevation Model - DEM) and the sun position. The hillshade creation function and various filtering techniques have been adopted. These techniques are based on the geometry of road segments in comparison to the sun position. The output of this analysis is the identification of road network parts that appeared at risk for a specific time period. The proposed method is implemented in Santorini Island during summertime period. The results in this case study shows that a significant part (5% of the total road network length) of the road network is highly exposed to the risk under investigation during the summer. Additionally, the implementation of the proposed method for a long time period allows a dynamic modeling of the conditions under investigation, and the adoption of various preventing actions.