Improved Safety and Efficiency of Protected/Permitted Right-Turns in Oregon
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Summary
This study addresses the safety and operational efficiency of protected/permitted right-turn (PPRT) operations at signalized intersections in Oregon, specifically evaluating the implementation of the flashing yellow arrow (FYA) signal indication. The research was motivated by established evidence that FYAs improve driver comprehension for permitted left turns, coupled with a lack of data regarding driver response to FYAs for right turns and steady red arrows in Oregon. Right-turning vehicles pose significant collision risks to pedestrians and bicyclists, particularly during permissive phases where yielding errors are common. The project aimed to determine if replacing steady circular green displays with FYAs could enhance driver-yielding behavior and pedestrian safety. The research employed a three-phase methodology following a comprehensive literature review and analysis of Oregon crash data from 2011–2013. First, a web-based survey assessed Oregon drivers’ comprehension of various right-turn signal displays, including steady red arrows and FYAs. Second, a microsimulation model evaluated the operational performance of several PPRT phasing alternatives, analyzing the impact of right-turn vehicle volumes, conflicting pedestrian movements, and conflicting left-turn vehicular movements on delay. Third, a driving simulator experiment examined motorist behavior and visual attention in response to right-turn signal displays. This experiment manipulated two independent variables: pedestrian activity levels and the length of turning bays, while measuring driver decision-making and eye-tracking data. The survey results revealed a general misunderstanding among drivers regarding the required response to steady red arrow signals, whereas comprehension of the FYA for right turns was high. The microsimulation analysis indicated that pedestrian volumes had the greatest effect on traffic delays across the tested phasing alternatives. The driving simulator experiment confirmed that driver responses were consistent with the survey findings, demonstrating that drivers understood the FYA indication. Visual attention data further supported the behavioral observations, showing distinct fixation patterns based on signal type and the presence of pedestrians. The study concludes that Oregon transportation agencies can improve driver-yielding behavior and pedestrian safety at signalized intersections with high volumes of permissive right turns from exclusive right-turn lanes by implementing the FYA display in lieu of a steady circular green display. The findings suggest that the FYA provides clearer communication of the permissive condition, highlighting potential risks for pedestrians and reducing yielding errors. These results support the adoption of FYAs for right-turn operations to maximize both safety for non-motorized road users and overall intersection efficiency.
Key finding
Using flashing yellow arrow displays instead of steady circular green signals improves driver-yielding behavior and pedestrian safety at signalized intersections with exclusive right-turn lanes.
Methodology
mixed_methods
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).
| Stage | Outcome | Tool | Model | Prompt | Attempts | Completed |
|---|---|---|---|---|---|---|
| discover | success | rosap | — | — | 2 | 2026-05-23 |
| archive | success | — | — | — | 1 | 2026-05-23 |
| extract | success | cached | — | — | 2 | 2026-06-10 |
| clean | success | — | — | — | 1 | 2026-06-01 |
| chunk | success | — | — | — | 1 | 2026-06-01 |
| embed | success | — | — | — | 1 | 2026-06-02 |
| 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 | success | — | — | — | 2 | 2026-06-10 |
Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.
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