Effects of Intersection Lighting Design on Nighttime Visual Performance of Drivers

Abstract

Nighttime crashes at intersections present a major traffic safety issue in the United States. Existing approach to intersection lighting design does not account for a driver's visual performance or the potential interactive effects of vehicle headlamps and roadway lighting. For effective design lighting at intersection, empirical research is required to evaluate the effects of lighting configuration (part of the intersection illuminated) and lighting levels on nighttime driver visual performance. The current study had two goals. First, to quantify visual performance in three lighting configurations (illuminating the intersection box, approach, or both). Second, to determine what lighting levels within each lighting configuration support the best visual performance. The study involved a target detection task, completed at night on a realistic roadway intersection.Illuminating the intersection box led to superior visual performance, as indicated by longer target detection distances, fewer missed targets, and more targets identified within a safe stopping distance. For this lighting configuration, visual performance plateaued between 7 and 10 lux of mean intersection illuminance. These results have important implications for the design of intersection lighting at isolated/rural intersections, specifically that illuminating the intersection box is an effective strategy to increase nighttime visual performance for a wider range of driver ages and could also be an energy efficient solution.

Effect of Intersection Lighting Design on Drivers’ Perceived Visibility and Glare

“…Illuminating different parts of an intersection leads to important differences in perceived visibility and glare, and the patterns of these differences are generally consistent with measures of visual performance (9). Illuminating the intersection box yielded the highest ratings of target and intersection visibility and the lowest ratings of glare.…”

“…Experimental Procedure. Experimental procedures were very similar to those used in the paper previously noted (9). Two participants were scheduled for each experimental session, and upon arrival they initialled the informed consent form and were provided with an overview of the experimental session by an experimenter in one of the vehicles used (Ford Explorers, model years 1999 and 2000).…”

“…Effect of intersection lighting configuration and light level on detection distance of drivers as reported in Bhagavathula et al ( 9 ). Values reported are means of detection distances of standard visibility targets and error bars represent standard errors.…”

“…( 17 ), and also result in higher perceived glare, as supported by existing research in this area ( 13 – 16 ). Results from this study were intended to supplement earlier results regarding visual performance ( 9 ), and to help determine whether intersection lighting designs that result in better visual performance also lead to improved visibility and lower glare.…”

“…A new systems-level approach to intersection lighting design was introduced by Bhagavathula et al ( 9 ). (Note that we use the term “intersection lighting design” to refer to both the part of the intersection illuminated and the recommended light level.)…”