Optimization of Configuration for Retro-reflective Sheeting in Guide Signs Based on Dynamic Intervention Technology

Based on psychological theories, the paper analyzed the relationship between the acuity and the brightness ratio of the letter and background in guide signs. Because the luminance values for the five grades of the retro-reflective sheeting were constant and the gap was wide in the GB5768-1999 Traffic Signs and Markings on the roads, the luminance values of the background were adjusted dynamically by adding declining sheeting onto it. By field experiments, the impact of the grade of retro-reflective sheeting on the visibility was studied, and the relationship between the luminance values and visibility distance was established. The results show that there exists a certain brightness ratio which can optimize visibility, and we get the best configuration for the retroreflective sheeting grade of letter and background when the luminance value of the letter is 600 cd·lx^-1·m^-2, that of the background is 92.5 cd·lx^-1·m^-2 with a visibility distance of 141.9m,which indicate that the current grade of the signs is high, and should be lowered.