Evaluation of Green Lights on TMAS

Brown, Henry; Sun, Carlos; Zhang, Siyang; Qing, Zhu; Edara, Praveen K. · 2018 · ROSA P / Missouri. Department of Transportation. Construction and Materials Division

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Summary

This study evaluates the effectiveness of green lights on Truck-Mounted Attenuators (TMAs) to improve safety in mobile work zones, motivated by a high incidence of TMA collisions in Missouri, primarily caused by distracted driving. The research aimed to determine the optimal light bar configuration by comparing traditional amber/white lights against green-only, green/amber, and green/white alternatives. The study employed a two-phase methodology: a driving simulator study assessing four configurations and a field study comparing green-only and amber/white setups. The simulator phase involved 30 participants who drove through virtual mobile work zones under both daytime and nighttime conditions. Researchers measured driver behavior metrics, including first blinker distance, merge distance, work zone recognition distance, and arrow direction recognition distance. Additionally, an eye-tracking test assessed disability glare by measuring participants' ability to recognize a water bottle placed near the TMA. The field study collected data from 4,966 vehicles on US 50, using LiDAR and video processing to record vehicle speeds as they passed TMAs equipped with either green-only or amber/white lights. Simulator results revealed an inverse relationship between work zone visibility and driver comfort. The amber/white configuration yielded the greatest recognition distances for the work zone but caused the highest levels of disability glare, with only 71% of participants recognizing the test object at night. Conversely, the green-only configuration produced the least disability glare (92% recognition) but resulted in significantly shorter recognition distances for the work zone. The green/amber configuration performed intermediately and was the most preferred option in post-simulator surveys, balancing visibility with reduced glare. Field study results indicated that lower TMA speeds correlated with lower passing vehicle speeds. When controlling for TMA speed, the green-only configuration resulted in slightly lower vehicle passing speeds compared to amber/white, particularly at night. The study concludes that no single light configuration is clearly superior, as each presents trade-offs between conspicuity and glare. While amber/white lights offer the highest visibility, they induce significant disability glare. Green-only lights reduce glare and may encourage slower passing speeds but are less visible. The green/amber combination emerged as the preferred compromise among participants. The findings suggest that while green lights are viable, their implementation requires careful consideration of the balance between alerting drivers to the work zone and avoiding visual impairment. This research provides the first quantitative assessment of green lights on TMAs in the United States, highlighting the need for further long-term studies to account for potential novelty effects.

Key finding

The amber/white TMA configuration provided the highest work zone visibility but caused the most disability glare, while the green/amber configuration was the most preferred by drivers for balancing visibility and comfort.

Methodology

mixed_methods

Sample size: 30

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_with_issues.

Topics

Ranked by relevance to this paper. Hover a topic for its definition.

• emergency work zone conspicuity
• vehicle conspicuity
• roadway lighting effects
• visibility analysis litigation
• motorcycle conspicuity