Human Factors Study on the Use of Colors for Express Lane Delineators

Abou-Senna, Hatem; Radwan, Essam; Mouloua, Mustapha; Wu, Jiawei; Michaelis, Jessica; Nager, Scott; El-Agroudy, Mohamed; Elsalamy, Mohamed; Tice, Patricia; Shaaban, Karim · 2019 · ROSA P / Florida. Department of Transportation

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Summary

This study addresses the need to determine the most effective color for express lane (EL) delineators, motivated by upcoming changes to the Manual on Uniform Traffic Control Devices (MUTCD). The 2009 MUTCD allowed orange or pavement-matching colors for channelizing devices, but proposed revisions restrict colors to match pavement markings only. Given the widespread use of ELs in Florida and the potential impact on driver safety and perception, the research aimed to evaluate how different marker colors affect driver awareness and performance across various demographics and driving conditions. The researchers conducted a human factors experiment using a driving simulator at the University of Central Florida. They recruited 176 participants across three age groups (18–39, 40–64, and 65+) and both genders, though only 134 completed the study due to factors like motion sickness or technical issues. Participants underwent vision screenings to filter for visual acuity and color blindness, followed by simulator sessions lasting approximately three hours. The experimental design varied driving conditions, including time of day, road surface type, traffic density, and visibility, while testing six marker colors: white, yellow, black, orange, purple, and retroreflective variants. Data collection included objective measures such as deceleration, braking time, lane deviation, and Time-to-First-Notice (TTFN) via eye-tracking, as well as subjective responses through exit surveys. Statistical analysis was performed using mixed models to assess the significance of color on these performance metrics. The results identified white as the optimal and most significant color for driver awareness and performance, followed by yellow, with black being the least desirable. White markers consistently yielded the lowest TTFN, indicating drivers noticed them earliest before entering the express lanes. In terms of lane deviation, drivers encountering white markers aligned further from the delineators, demonstrating strong awareness of the lane boundary, whereas black markers resulted in vehicles aligning closer to the markers, particularly at night, due to poor visibility. White markers were most significant in straight sections, while yellow was most significant in curved sections. Both objective data and subjective survey responses aligned, confirming that white markers provided the highest noticeability and safety margin. The use of retroreflective sheets was also found to significantly enhance noticeability during nighttime scenarios. The significance of these findings lies in their potential to inform future MUTCD standards and the implementation of express lanes. By establishing white as the superior color for delineators, the study supports safer and more efficient freeway operations. The authors also note that while the results are conclusive for human perception, further research is needed to understand how these color choices impact machine perception for automated and alternatively powered vehicles, ensuring safe integration of emerging technologies like driverless cars.

Key finding

White delineator markers demonstrated the highest driver awareness and performance metrics, followed by yellow, whereas black markers resulted in the highest miss rates and lowest optimality.

Methodology

simulator

Sample size: 134

Provenance

The full processing record for this entry. Every stage of this paper's journey through the pipeline is logged — what ran, with which tool and model, how many attempts it took, and when it last completed. Discovered via bulk_ingest_rosap on 2026-05-23 (6 acquisition events logged).

Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.

Topics

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• emergency work zone conspicuity
• perceptual countermeasures
• vehicle conspicuity
• roadway lighting effects
• sensory abilities
• vru conspicuity

Information type

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• Empirical Findings: behavioral performance data
• Methodological Resource: tool software, measurement protocol