Characteristics and Predictors of Occasional Seat Belt Use Using Strategic Highway Research Program 2 Data

Richard, Christian M.; Thomas, F. Dennis; Blomberg, Richard D.; Brown, James L.; Wright, Timothy J.; Graham, Lindsey A.; Lee, Joonbum; Landgraf, Andrew · 2020 · ROSA P / United States. Department of Transportation. National Highway Traffic Safety Administration

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Summary

This study investigates the characteristics and predictors of occasional seat belt use, addressing the gap in understanding why approximately 10% of drivers use seat belts inconsistently despite high national usage rates. Motivated by the need to develop targeted countermeasures for this group, the research utilized data from the Strategic Highway Research Program 2 (SHRP2) Naturalistic Driving Study. The primary objectives were to identify individual factors differentiating seat belt user groups and to determine how situational factors influence the belt-use patterns of occasional users. The researchers analyzed seat belt status data from 895 SHRP2 participants, categorizing trips as fully buckled (>95% use), fully unbuckled (<5% use), or partially unbuckled. Participants were classified into user types based on their trip patterns, identifying two distinct groups of occasional users: those who made pre-trip decisions to buckle or unbuckle for the entire trip, and those who made within-trip decisions to change status. The study employed statistical and machine-learning models to compare consistent users against occasional users, and further differentiated between the two types of occasional users. Additionally, researchers examined situational predictors by analyzing trip-wide variables, comparing driving epochs (buckled vs. unbuckled segments), and reviewing video data to identify immediate conditions surrounding buckling and unbuckling events. The findings revealed that occasional seat belt users were significantly more likely to be older, male, overweight, single, and have more traffic violations. They also exhibited lower risk perception regarding unbuckled driving, higher risk-taking scores, and poorer performance on cognitive tests compared to consistent users. Differentiating the two types of occasional users, those who typically unbuckled for full trips were younger, had higher sensation-seeking and thrill-seeking scores, and were more likely to work night shifts. Situational analysis showed that unbuckled trips were shorter, slower, and occurred on lower-capacity roads. Video coding indicated that drivers often unbuckled on low-risk local roads or when distracted, while buckling was frequently triggered by approaching intersections, the presence of passengers, or the perception of law enforcement. Notably, only about 20% of unbuckled drivers buckled after experiencing a crash or near-crash, suggesting that such events rarely serve as lasting deterrents for this group. The study concludes that occasional seat belt use is driven by a complex interplay of demographic, psychological, and situational factors. The distinction between pre-trip and within-trip decision-making highlights that occasional users assess risk dynamically based on trip characteristics. These findings provide a detailed profile of occasional users, offering evidence-based insights for developing targeted safety interventions and countermeasures aimed at converting occasional users into consistent seat belt users.

Key finding

Occasional seat belt users were more likely to be older, male, single, overweight, and have higher risk-taking scores, while their use patterns were predicted by shorter trip distances, lower average speeds, and specific trip start times.

Methodology

naturalistic

Sample size: 895

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

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• seat belt use
• child passenger safety

Information type

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• Empirical Findings: observational prevalence, crash risk outcomes, behavioral performance data