Caltrans UAS and Driver Safety: Driver Distraction in the Presence of UAS

Akhavian, Reza; Machiani, Sahar Ghanipoor; Kusha, Zainab Afzali · 2024 · ROSA P / California. Department of Transportation

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Summary

This study investigates driver distraction caused by roadside infrastructure inspection methods, specifically comparing Unmanned Aerial Systems (UAS) against traditional Under-Bridge Inspection Trucks (UBITs). Motivated by the increasing use of drones in civil engineering and the safety risks associated with work zone lane closures, the research aims to determine which method poses less risk to drivers and how operational conditions influence distraction levels. The study builds upon previous research by expanding the sample size and incorporating multi-modal data analysis to provide a more comprehensive assessment of cognitive and visual distraction. The researchers conducted a driving simulator experiment involving 64 participants. Each participant completed 30–40 minutes of driving sessions, including a control baseline and scenarios featuring either a UAS or a UBIT. The experimental design varied traffic density (low and high), traffic speed (25 and 60 mph), and UAS size (small DJI Mini 2 vs. large DJI Matrice 600). Data collection utilized an innovative multi-modal approach, combining eye-tracking technology to measure visual fixations with Electroencephalography (EEG) headsets to record brain signals. This combination allowed for the validation of eye-tracking results with physiological data, providing deeper insights into cognitive load and attention shifts that eye-tracking alone might miss. The results indicated that UAS operations are significantly safer than UBIT operations, causing substantially less driver distraction. The average Total Fixation Duration (TFD) was 0.9 seconds for UAS scenarios compared to 1.4 seconds for UBIT scenarios. Crucially, both averages remained well below the two-second threshold established in literature as the maximum safe distraction duration, suggesting both methods are within acceptable safety limits, though UAS is preferable. In UBIT scenarios, traffic density and speed did not statistically affect distraction levels; drivers consistently glanced at the trucks regardless of conditions. Conversely, in UAS scenarios, UAS size had no significant impact on distraction, but traffic density and speed did. Specifically, traffic speed significantly influenced distraction during high-density traffic, while EEG models indicated varying impacts of speed and density depending on the specific analytical model used. The significance of these findings lies in providing evidence-based guidance for transportation agencies implementing roadside inspection technologies. The study confirms that UAS offers a safer alternative to lane-closing UBITs by minimizing driver distraction. Furthermore, the results highlight that while UAS size is not a critical factor for safety, traffic conditions such as speed and density must be carefully considered when deploying drones near roadways. The successful application of combined EEG and eye-tracking data demonstrates the value of multi-modal analysis in accurately assessing complex driver states, offering a robust framework for future research on driver behavior and safety in dynamic traffic environments.

Key finding

UAS operations cause substantially less driver distraction than Under-Bridge Inspection Truck operations, with both remaining within acceptable safety limits.

Methodology

simulator

Sample size: 64

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).

StageOutcomeToolModelPromptAttemptsCompleted
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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