Investigation of the Use and Feasibility of Speed Warning Systems [Traffic Tech]

NHTSA · 2014 · ROSA P / United States. National Highway Traffic Safety Administration

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Summary

This study, conducted by the National Highway Traffic Safety Administration (NHTSA) in 2014, investigated the feasibility and effectiveness of vehicle-based speed warning systems for habitual speeders. Motivated by the persistent problem of speeding-related crashes and the limited success of traditional speed management practices, the research aimed to determine if real-time feedback could deter chronic speeding. The study focused on adult drivers with multiple speeding citations, examining whether an audible warning system could reduce speeding behavior during a naturalistic field study. The research design involved a naturalistic field study with 83 eligible participants recruited from Maryland drivers who had at least three speeding citations in the previous three years. Participants were stratified by age (21–29 and 30+) and gender. Each participant’s vehicle was equipped with a monitoring device that provided continuous travel and speed data. The study utilized a three-phase design: a baseline period with no feedback, a treatment period where an audible “Speeding violation” warning was triggered when driving exceeded the posted limit by 8 mph, and a post-treatment period with feedback disabled. Most participants experienced a two-week baseline, a four-week treatment, and a two-week post-treatment phase, while a small subsample underwent an eight-week treatment period. The results indicated that the warning system produced short-term changes in driving behavior but also revealed displacement effects. During the treatment period, the percentage of driving exceeding the posted speed limit by more than 8 mph decreased significantly from 18% at baseline to 13%. Similarly, driving at least 20 mph over the limit dropped from 26% to 18%. However, drivers compensated by increasing their speeding within the 0–8 mph range above the limit, rising from 27% to 29% during treatment. Consequently, the overall percentage of driving over the posted limit showed only a marginal decrease, dropping from 45% at baseline to 43% during treatment. In the post-treatment phase, speeding behaviors partially reverted; for instance, speeding over 8 mph rose to 16%, and speeding over 20 mph increased to 22%, though the latter was not statistically different from baseline. Age differences were observed, with drivers aged 30+ speeding less frequently than those aged 21–29, but no significant gender differences were found. The study concludes that while speed warning systems can effectively reduce severe speeding (exceeding the alert threshold), they may inadvertently encourage drivers to speed just below the warning threshold. This suggests that such technology has promise as a tool for reducing speeding among habitual offenders, particularly for extreme violations, but its overall impact on total speeding incidence is limited by behavioral adaptation. The findings highlight the need for careful consideration of threshold settings and the potential for carryover effects when evaluating the long-term efficacy of such interventions.

Key finding

Speeding more than 8 mph over the posted limit dropped from 18 percent of travel at baseline to 13 percent when the audible feedback alert was active.

Methodology

naturalistic

Sample size: 83

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 (8 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.

• speed management
• automated enforcement cameras
• speed choice
• perceptual countermeasures

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).

• Applied Guidance: countermeasure evaluation
• Empirical Findings: observational prevalence