The innovative road marking ‘Optical Dot System’ (ODS) was conceived through the ‘Sequence Design’ (SD) project for driving environment improvement, seeking a new approach of the measures for safety in Metropolitan Expressways (MEX) in 2006. In this paper we attempt to report the circumstances of ODS development including the experiments and evaluations. ODS has been installed on a two lane highway in MEX, at the section of vertical alignment beyond the junction, where 60% of total traffic exceeded the speed limit.
Soon after the installation, a speed reduction was observed in high speed traffics areas with a downward grade, especially in the nighttime. The shift showed a nearly 20% decrease from the high range (100-120km/h) to the mid-range (80-100km/h). In parallel, we performed the subject experiment at the laboratory in Univ. of Tokyo (UT) to evaluate the direct impact of ODS to drivers’ perception and behavior by using the Driving Simulator³⁾ to generate Virtual Reality of the highway. The experimental results supported the hypothesis that driving was controlled by ODS. After four years of the installation in MEX, we analyzed the collected data in the section of ODS to verify the transition for six years (incl. two years data before the installation). The resulting trend in speed reduction has been maintained through the four years. The sustainable long term effectiveness of ODS has been proven.