Risk evaluation for in-vehicle sign information.

Schlicht, Erik J.; Morris, Nichole · 2016 · ROSA P / Minnesota. Dept. of Transportation. Research Services & Library

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Summary

This study evaluated the safety implications and potential distraction associated with In-Vehicle Sign (IVS) information displayed on personal navigation devices. Motivated by the Minnesota Department of Transportation’s Connected Vehicles Program, the research aimed to determine if IVS could effectively assist drivers in preparing for changing driving conditions—specifically speed zone changes, school zones, work zones, and curves—without compromising safety or increasing cognitive workload. The study sought to assess whether IVS could serve as a viable supplement to or replacement for traditional roadside signage. The researchers employed a 2x2 mixed-factorial experimental design using the HumanFIRST driving simulator. Forty participants, balanced for age and gender, were divided into two groups: one receiving IVS information alongside external roadside signs (IVS +ES) and the other receiving IVS information in the absence of external signs (IVS -ES). All participants completed baseline drives with only external signs. The simulated route was 24 miles long, featuring freeway, rural, and town driving segments with specific zones triggering visual IVS alerts on an Android phone mounted on the center console. Data collection included objective driving performance metrics (average speed, speed variability, lane position deviation) and subjective measures of mental workload (NASA-RTLX) and usability. Additionally, a Monte-Carlo risk analysis was conducted to estimate safety outcomes relative to crash types. The results indicated that IVS deployment significantly impacted driving behavior depending on the presence of external signs. When IVS was used without external signs (IVS -ES), speeding behavior increased significantly compared to baseline levels, and speed variability decreased, suggesting drivers failed to appropriately adjust to posted limits. Consequently, risk analysis revealed that safety across all crash types was significantly reduced below baseline in the IVS -ES condition. Subjective measures corroborated these findings, showing increased mental workload and decreased satisfaction for the IVS -ES group. Conversely, when IVS was used in conjunction with external signs (IVS +ES), driving performance remained comparable to baseline levels. Notably, risk analysis suggested that the IVS +ES condition could improve safety regarding frontal-impact crashes. Lane position deviations were unaffected in either IVS condition, indicating that lateral vehicle handling was not compromised. The study concludes that IVS technology should not be utilized as a substitute for external roadside signs, as doing so leads to increased speeding, higher crash risk, and greater driver workload. However, the findings support further exploration of IVS as a complementary tool used alongside traditional signage. In this combined configuration, IVS maintains baseline safety levels while potentially enhancing protection against frontal-impact crashes, without negatively affecting driver satisfaction or mental workload. These results provide critical guidance for the implementation of connected vehicle technologies, emphasizing the necessity of redundant signage to ensure safe driver compliance.

Key finding

In-vehicle signing without external roadside signs significantly increased speeding and reduced overall crash safety, whereas in-vehicle signing combined with external signs improved frontal-impact crash safety and maintained baseline driving performance.

Methodology

simulator

Sample size: 40

Provenance

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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.

• external distraction
• signage environment
• ehmi external hmi
• exposure measurement
• induced exposure
• useful field of view

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: crash risk outcomes, observational prevalence
• Methodological Resource: tool software