Date of Defense
11-6-2025 12:15 AM
Location
F1-1124
Document Type
Dissertation Defense
Degree Name
Doctor of Philosophy in Architectural Engineering
College
COE
Department
Architectural Engineering
First Advisor
Dr. Ahmed Hassan
Keywords
Roadway lighting, lighting design, nighttime visibility, pedestrians, roadway safety, contrast, traffic safety, sustainable cities, useful contrast index, mean contrast index.
Abstract
Roadway lighting standards specify design targets of horizontal illuminance or luminance at the roadway surface for various roadway types. Although the luminance and illuminance method to roadway lighting standards incorporate some factors that affect human visibility, other important factors, such as the target’s contrast and size, are not examined in these standards. Roadway lighting standards should consider how the human visual system detects objects and provides comfortable approaches to improve visibility for drivers. As luminous contrast has a crucial impact on visibility measures, recent studies have been directed to propose new approaches that utilize it. This research aims to propose new roadway design indexes based on the contrast of obstacles and to investigate whether they can be integrated with or replace the design based on luminance or illuminance. An experimental program was performed on a two-lane road located in Falaj Hazzah. Grids comprising five models, each model representing obstacles of different heights (0.05, 0.5, 1.0, 1.5 m), were distributed along the lateral and longitudinal directions of the road and systematically moved between two streetlights. A vehicle-mounted camera was placed at a distance equal to the total stopping distance from each obstacle to capture calibrated high-dynamic-range (HDR) luminance maps for diverse scenarios. HDR images provided detailed luminance data to evaluate factors influencing contrast. The dynamic of contrast results was investigated under various roadway lighting design variables, such as pole spacings, lumen output, and vehicle headlights. Dialux software was utilized to replicate the existing road to validate the model as a design tool. The contrast results were then used to propose two different metrics for roadway lighting standards, named the Useful Contrast Index (UCI) and the Mean Contrast Index (MCI). The performance of the proposed metrics was evaluated by changing lighting design variables such as lumen output and pole spacings. Results showed a weak correlation between obstacle contrast and road pavement luminance, highlighting the need to incorporate new contrast-based approaches into current roadway lighting design. For very low obstacles, contrast decreased with increased lumen output, whereas for taller obstacles (1.5 meters), contrast improved with higher lumen output. While reduced pole spacing increased pavement luminance, it did not increase the contrast of obstacles. The results also show that the proposed contrast-based indexes have merit and could be integrated into current roadway lighting guidance, aiming at enhancing the visual environment for drivers and improving safety.
Included in
NEW CONTRAST-BASED METRICS FOR ROADWAY LIGHTING DESIGN
F1-1124
Roadway lighting standards specify design targets of horizontal illuminance or luminance at the roadway surface for various roadway types. Although the luminance and illuminance method to roadway lighting standards incorporate some factors that affect human visibility, other important factors, such as the target’s contrast and size, are not examined in these standards. Roadway lighting standards should consider how the human visual system detects objects and provides comfortable approaches to improve visibility for drivers. As luminous contrast has a crucial impact on visibility measures, recent studies have been directed to propose new approaches that utilize it. This research aims to propose new roadway design indexes based on the contrast of obstacles and to investigate whether they can be integrated with or replace the design based on luminance or illuminance. An experimental program was performed on a two-lane road located in Falaj Hazzah. Grids comprising five models, each model representing obstacles of different heights (0.05, 0.5, 1.0, 1.5 m), were distributed along the lateral and longitudinal directions of the road and systematically moved between two streetlights. A vehicle-mounted camera was placed at a distance equal to the total stopping distance from each obstacle to capture calibrated high-dynamic-range (HDR) luminance maps for diverse scenarios. HDR images provided detailed luminance data to evaluate factors influencing contrast. The dynamic of contrast results was investigated under various roadway lighting design variables, such as pole spacings, lumen output, and vehicle headlights. Dialux software was utilized to replicate the existing road to validate the model as a design tool. The contrast results were then used to propose two different metrics for roadway lighting standards, named the Useful Contrast Index (UCI) and the Mean Contrast Index (MCI). The performance of the proposed metrics was evaluated by changing lighting design variables such as lumen output and pole spacings. Results showed a weak correlation between obstacle contrast and road pavement luminance, highlighting the need to incorporate new contrast-based approaches into current roadway lighting design. For very low obstacles, contrast decreased with increased lumen output, whereas for taller obstacles (1.5 meters), contrast improved with higher lumen output. While reduced pole spacing increased pavement luminance, it did not increase the contrast of obstacles. The results also show that the proposed contrast-based indexes have merit and could be integrated into current roadway lighting guidance, aiming at enhancing the visual environment for drivers and improving safety.