Institute for Transportation

About the research

Nighttime work zones pose increased risks for both drivers and workers due to the challenge of ensuring adequate visibility while minimizing glare. Current lighting practices vary widely across public agencies, often resulting in excessive illumination and poor glare control. This study evaluated the performance of nighttime lighting systems through two phases: (1) an industry survey and (2) a controlled field experiment along with a qualitative task assessment and analysis. The survey, with 116 responses, identified persistent issues related to glare and uneven light coverage, primarily attributed to improper lighting configurations rather than insufficient light output. The field study tested 126 lighting setups using LED and halogen lighting sources set at varying mounting heights, aiming angles, and rotation angles. Measurements included horizontal and vertical illuminance, pavement luminance, and veiling luminance ratio (VLR). Results showed that the lighting setups—rotation angle and mounting height—had the greatest impact on visibility and glare. Optimal configurations (rotation: 40°–50°, height: 12–13 ft, aiming angle: 20°–40°) could provide better visibility and minimize harmful glare in the vicinity of nighttime work zones. The report provides recommendations for optimal lighting configurations, offering agencies practical guidance to improve safety and visibility in nighttime work zones.