Yellow pedestrian crossings: from innovative technology for glass beads to a new retroreflectivity regulation

Abstract

Horizontal road markings are common and inexpensive road safety features, which are particularly needed and effective during night time driving, when the embedded glass beads provide retroreflectivity, which is perceived by drivers while other visual cues are limited. Worldwide, there are different standards for the minimum retroreflectivity levels: the most recent recommendation for coefficient of retroreflected luminance (RL) from European Road Federation is 150 mcd/m2/lx. Such level can be readily achieved and maintained in white paint, but not in yellow. In Switzerland, yellow colour is used for marking of pedestrian crossings, which necessitated lower RL. The recently introduced premium type of glass beads was found to furnish RL exceeding the requirements and simultaneously provides longer service life, which led to modification of the Swiss norms and increase of the minimum RL from 60 mcd/m2/lx to 150 mcd/m2/lx for used markings. In addition, substantial RL was achieved under the condition of wetness. The study has shown that shade of the yellow colour also played profound role in the on-road performance. This emerging technological advance has a potential to affect the road administrators’ policies toward reflectorisation of horizontal road markings worldwide. Improved road safety can be realised by increasing the conspicuity of markings and, therefore, pedestrians. Furthermore, the measured increased durability can directly transfer into lesser environmental burden.