Road marking retroreflectivity study via a visual algorithm

Abstract

The retroreflectivity (Rl) of road markings is important and should be inspected and maintained throughout their service life. The specifications are provided by European nations, the United States, and many other countries. Although acceptance tests ensure the good Rl quality of newly placed road markings, the RL values of all in-service road markings are rather difficult to inspect by using currently available devices. This study, therefore, aims to determine the relationship between Rl and corresponding image brightness of yellow road markings to evaluate their visibility by analyzing recorded images captured at night. An integrated algorithm was developed to analyze recorded images continuously for identifying road marking brightness 30 m away from a vehicle. Field experiments on three types of road marking materials were performed and repeated at four separate locations. The findings provide a promising direction for using the image brightness of road markings to predict their field Rl. However, limitations of this study are discussed and suggestions for future direction are presented.