Impact of alcohol on lane placement and glance patterns when passing a parked active law enforcement vehicle.

Finley, Melisa D.; Miles, Jeffrey D. · 2014 · ROSA P / Center for Advancing Transportation Leadership and Safety (ATLAS Center)

archive: archived pipeline: cataloged verified

Get this paper ↗ (full text — opens at the source; we link to it, we don't host it)

Summary

This study investigates the "moth effect" theory, which posits that drivers drift toward bright lights, specifically examining how alcohol impairment influences lane placement and glance patterns when passing a parked law enforcement vehicle with activated overhead flashing lights. The research was motivated by the high prevalence of alcohol-impaired driving fatalities and the need to understand how impairment affects driver behavior in the presence of bright, distracting light sources. The study utilized an existing dataset from a larger Texas Department of Transportation project focused on sign recognition, repurposing data collected during a nighttime closed-course driving experiment. The experimental design involved 10 male participants who drove instrumented vehicles along a simulated two-lane roadway at night. Data were collected at two blood alcohol concentration (BAC) levels: 0.00 g/dL (sober) and 0.12 g/dL (impaired). Researchers employed GPS for speed and lateral position tracking, an eye-tracking system to record gaze points and pupil diameter, and external cameras to determine precise lane placement relative to pavement markings. Participants drove past a stationary law enforcement vehicle with its light bar activated. Statistical models analyzed lateral distance, pupil diameter, and vehicle speed as functions of BAC level, gaze direction, and distance traveled toward the vehicle. The results confirmed the moth effect theory, showing that all participants drifted toward the law enforcement vehicle approximately 200 feet upstream of the vehicle, moving laterally between 8 and 24 inches closer to the edgeline. On average, participants at a BAC of 0.12 g/dL drifted farther toward the vehicle (15.7 inches) compared to those at 0.00 g/dL (14.6 inches), though individual responses varied significantly. Regarding visual behavior, participants at the higher BAC level looked directly at the law enforcement vehicle less frequently, likely due to increased glare sensitivity caused by alcohol-induced pupil dilation. Consistent with physiological expectations, the majority of participants exhibited larger average pupil diameters at a BAC of 0.12 g/dL than at 0.00 g/dL. Vehicle speed differences between BAC levels were found to be practically negligible, with sober participants generally driving more conservatively. The findings provide empirical support for the moth effect theory, demonstrating that drivers are drawn toward bright lights even when impaired. The study highlights that alcohol impairment exacerbates this lateral drift and alters visual attention patterns, specifically reducing direct glances at bright sources due to physiological changes in pupil response. These results have implications for traffic safety and law enforcement practices, suggesting that the placement and lighting of parked enforcement vehicles may inadvertently influence driver lane positioning, particularly among impaired drivers. The study underscores the complex interplay between alcohol impairment, visual physiology, and vehicle control in nighttime driving scenarios.

Key finding

Drivers drifted toward a parked law enforcement vehicle with activated lights within 200 feet of the vehicle, moving laterally 8 to 24 inches, although all participants remained within lane boundaries and the drift magnitude varied by individual.

Methodology

simulator

Sample size: 10

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

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

• alcohol

Information type

What kind of knowledge this paper contributes, grouped by family — independent of topic (what it is about) and method (how it was studied).

• Empirical Findings: behavioral performance data
• Methodological Resource: measurement protocol