Roadside Assistance Vehicle Lighting: Review of Scientific Research and State Regulations

AAA Foundation for Traffic Safety · 2025 · AAA Foundation for Traffic Safety

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Summary

This report by the AAA Foundation for Traffic Safety addresses the critical safety issue of roadside assistance vehicle (RSV) visibility. Tow trucks and other service vehicles operate in diverse and often hazardous conditions, requiring lighting solutions that enhance their conspicuity to approaching motorists. The study was motivated by the lack of clear consensus on optimal lighting configurations due to mixed research findings and inconsistent state regulations. The primary objectives were to synthesize existing scientific literature on RSV lighting properties and to review state laws governing warning light usage across the United States. The methodology involved a comprehensive literature review of over 1,200 screened articles, from which 30 relevant studies were selected. These studies were analyzed for outcomes related to device type, light quantity, mounting location, size, color, flash rate, pattern, intensity, and vehicle markings. Additionally, the researchers reviewed statutes and administrative rules for all 50 states, the District of Columbia, and Puerto Rico to identify regulations concerning warning light colors and usage conditions. Key findings indicate that several lighting techniques effectively draw attention to RSVs, particularly at night. These include using LED lightbars, faster flash rates (approximately 4 Hz), higher luminous intensity, and increasing the number of lights to two or four per display. Alternating flash patterns (left/right “wig-wag”) were found to be more detectable than simultaneous or complex random patterns. While amber and green lights are highly visible, they produce more glare than other colors. Drivers strongly associate amber with road maintenance and red/blue with emergency services. However, the review highlights a significant trade-off: interventions that improve long-distance vehicle visibility, such as high-intensity lights, often increase disability glare and reduce the visibility of personnel working on foot near the vehicle. Furthermore, inverted V stripe markings were found to have less adverse impact on night visibility of workers compared to checkerboard patterns. The significance of this research lies in its identification of critical gaps between scientific evidence and regulatory frameworks. State regulations regarding RSV lighting are remarkably inconsistent, varying by allowable colors and usage conditions, which creates legal complexities for multi-state operations. Most statutes remain silent on technical parameters like intensity and flash patterns. The report concludes that current lighting practices may inadvertently endanger roadside workers by exacerbating glare issues. It underscores the need for further research to balance vehicle conspicuity with personnel safety and suggests that standardized regulations could help resolve the current variability in state laws.

Key finding

Evidence suggests that LED lightbars with faster flash rates, higher intensity, and alternating patterns improve roadside assistance vehicle detection, but increased lighting intensity can cause glare that reduces the visibility of nearby personnel.

Methodology

review

Sample size: 30

Provenance

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enrich success 1 2026-05-23
promote success 1 2026-05-23
summarize success llm qwen3.6-27b-prismaquant summ-v5 3 2026-06-10
tag success vector_similarity 19 2026-06-11
verify partial 2 2026-06-10

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