Development and real-world testing of micro phase-change photoluminescent material based traffic signs for improved nighttime visibility and safety

Nighttime visibility and safety are an aspect of vital importance for improving road safety. In this regard, much effort has been spent on developing persistent luminescence materials to be used as road markings, however, little to no attention has been paid to the development of road signs and edge barriers which play a vital role in traffic safety. The presented research work details the development, lab, and real-world testing of micro phase-change photoluminescent material-based traffic signs that have the ability to glow throughout the night period. The persistent luminescence materials tend to lose their glow intensity with the passage of time; however, the research team overcame this challenge by utilizing ultraviolet light to excite the material in order to achieve the desired level of glow intensity. Various options of ultraviolet light sources ranging from UVA to C were tested in order to formulate an optimal combination for achieving high glow intensity and glow duration. Through the trial-and-error approach, the researchers were able to identify the use of a 395 nm, light source for exciting photoluminescence material. The presented glow-in-the-dark sign has the ability to glow consistently at an minimum average brightness of 7.5 LUX for a duration of 10 h. The newly developed sign has been tested under adverse environmental conditions of rain, fog, and sandstorms in harsh environment conditions. The presented new class of persistent photoluminescence traffic sign can be adopted for providing active safety to road users.