A Study on Designing the Landscape of Roundabout Central Islands for Improved Traffic Safety

Abstract

Among the components of a roundabout, the central island is thought to afford improved traffic safety and landscape by incorporating landscape design features such as a mound and vegetation. However, there are no specific regulations on landscape design for roundabout central islands in Japan. In addition, few studies have addressed and quantitatively validated the correlation between landscape design and driving behavior, and the relationship is not necessarily evident. This study clarifies the effect of the mound on guiding driver’s eye movements through driving experiments, in order to explore landscape designs for central islands that would improve traffic safety and landscape appearance. It was found that for a central island of 12 m in diameter with a mound of 0.4 and 1.2 m in height, the driver’s eye movements were appropriately guided when the vehicle entered the circulatory roadway and that the driver’s subjective evaluations of traffic safety and driving comfort were higher than for islands of other specifications.