Gradient illumination scheme design at the highway intersection entrance considering driver's light adaption

Area of Science:

• Traffic safety engineering
• Illumination engineering
• Human factors in transportation

Background:

• Highway intersection lighting improvements can significantly reduce crash likelihood.
• Gradient illumination schemes enhance driver safety by managing pupil area changes between unlighted and lighted zones.

Purpose of the Study:

• To design illumination transition zones for drivers approaching highway intersections.
• To optimize illumination increments within these transition zones for enhanced safety.

Main Methods:

• Developed an indoor simulation platform (UC-win/road) calibrated with real-world night intersection data.
• Analyzed pupil area variations under different illuminance increase rates (INDE) and modeled pupil contraction.
• Created an optimization model to determine optimal luminance rates by minimizing driver transition time.

Main Results:

• Transition zone length is directly proportional to the intersection's speed limit.
• Transition zone length requires adjustment (extension/shortening) corresponding to speed limit changes.
• Illuminance increasing time in the transition zone is constant for a given intersection illumination.

Conclusions:

• Illumination transition zones are essential for highway intersections with INDE > 8 lx and speed limits > 40 km/h.
• Maintaining optimal INDE increasing rates ensures safe light adaptation and prevents accidents.
• Findings provide a scientific basis for implementing safer highway intersection lighting.