Apparent Luminance Improvement and Optical Mechanism of Recessed Pavement Markings

Limited visibility remains a key barrier to the wider application of recessed pavement markings in cold regions. In standard nighttime evaluations, the coefficient of retroreflected luminance (RL) is the primary indicator because drivers perceive pavement markings mainly through headlamp light retroreflected toward the observation direction. However, the apparent visibility of recessed pavement markings can also be influenced by groove-induced optical shielding, abrasion-induced changes in glass bead exposure, and supplementary emission from self-luminous materials. Therefore, camera-based apparent luminance measured under controlled imaging conditions was used as a driver-oriented comparative indicator, while RL was retained as the standard reference for validation and threshold interpretation. TracePro optical simulation was used to examine the relative light-propagation mechanisms and parameter sensitivity of recessed pavement markings. Single-factor tests were conducted to evaluate apparent-luminance evolution and identify preferred parameter ranges under the tested laboratory conditions. The results indicated that glass bead dosage, morphology, and optical properties strongly affected the apparent luminance of recessed pavement markings. A 6% yellow–green energy-storage self-luminous material was selected because of its favorable afterglow luminance and coating performance. Combining the selected glass bead design with self-luminous treatment improved the apparent luminance of recessed pavement markings and extended the luminance-retention period under laboratory abrasion conditions.