Road Marking Contrast Threshold for the Elderly and the Impact of Glare

As the global population continues to age, with projections indicating that individuals over 60 will comprise 17% of the world’s population by 2030, it is crucial to address the disparity between current road lighting guidelines, based on data from healthy young adults, and the needs of elderly drivers. This study examines the impact of age and glare on contrast thresholds for individuals above 60 years old in the context of road lighting and its effect on detecting road marking arrows. Results indicate a large negative effect of age and glare, such that the required luminance difference between the road marking arrow and the background should be increased up to a factor of 2 for elderly compared to young drivers. We also found that measured luminance difference thresholds increased for elderly participants compared to the younger ones. In addition, the results show a poor agreement with Adrian’s visibility model which can only be slightly improved by using a different measure for the veiling luminance. Still, given these findings, the current European standard EN13201 should adapt the calculation of the threshold increment to also accommodate the needs for the elderly drivers and warranting safe roadways for the aging population.