Effectiveness of Crash Fact/Safety Message Signs on Dynamic Message Signs

Savolainen, Peter T.; Gates, Timothy J.; Kassens-Noor, Eva; Megat-Johari, Megat-Usamah; Megat-Johari, Nusayba; Decaminada, Travis; Cai, Mengyu · 2021 · ROSA P / Michigan. Department of Transportation

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Summary

This study evaluates the effectiveness of using roadside Dynamic Message Signs (DMS) to display safety messages and crash facts, addressing a gap in research regarding their impact on driver behavior and traffic crashes. Sponsored by the Michigan Department of Transportation (MDOT) and conducted by Michigan State University, the research was motivated by the widespread adoption of DMS for safety messaging since 2010, despite limited evidence of their efficacy. The study aimed to determine if these messages influence driver compliance and crash rates, providing insights for future policy. The researchers employed a multi-method approach combining public opinion analysis, crash data evaluation, and field studies. First, they analyzed public perceptions through media content reviews (emails, social media, news sites) and a statewide survey of Michigan residents. Second, they conducted statistical analyses of crash data from 202 freeway DMS sites, integrating message frequency with roadway geometry, traffic volume, and crash records from 2012 to 2018. Third, they performed field evaluations to measure immediate driver responses to specific messages, focusing on compliance with the state’s “move-over” law for emergency/service vehicles and adherence to speed limits. These field studies compared driver behavior when exposed to targeted safety messages versus standard travel time messages, accounting for contextual factors like vehicle type on the shoulder and traffic volume. The findings revealed mixed results. Public opinion was largely split on the appropriateness of safety messages, with only 25% of survey respondents reporting that such messages improved their driving behavior. Crash analysis showed no significant difference in total or nighttime crashes based on message frequency. However, speeding-related crashes were significantly lower downstream of DMS displaying high frequencies of messages related to speeding or tailgating. Field studies indicated that message type had minimal impact on overall driver behavior; however, drivers were more likely to drive at or below the speed limit when targeted move-over messages were displayed compared to standard travel time messages. Crucially, compliance with both speed and lane requirements was significantly higher when the roadside vehicle was a police car rather than a transportation service vehicle. Speeding-related messages alone showed virtually no change in driver speeds. The study concludes that DMS safety messages have limited standalone effectiveness and should be used as part of active, short-duration safety campaigns rather than for continuous display of crash facts. The results align with Federal Highway Administration guidance, suggesting that safety messages are most effective when coupled with enforcement or specific high-risk behavior targeting. The authors recommend that MDOT prioritize travel and weather advisories but consider displaying safety messages at locations where high-priority messages are infrequent, particularly when integrated with broader enforcement initiatives.

Key finding

Speeding-related crashes were significantly lower downstream of dynamic message signs displaying higher frequencies of speeding or tailgating messages, while targeted move-over messages improved driver speed compliance compared to standard travel time messages.

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).

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.

• public messaging
• signage environment
• external distraction
• 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: crash risk outcomes, observational prevalence