A Driving Simulator Study to Evaluate the Impact of Portable Changeable Message Signs (PCMS) on Drivers’ Speed Characteristics in Work Zones

Bham, Ghulam H; Leu, Ming C.; Venkat, Bharat K; Mohammadi, Mojtaba Ale · 2014 · ROSA P / Midwest States Smart Work Zone Deployment Initiative (SWZDI)

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Summary

This study investigates the effectiveness of Portable Changeable Message Signs (PCMS) in reducing driver speeds within highway work zones, addressing the critical safety issue of speeding, which contributes significantly to work zone fatalities and injuries. Sponsored by the Midwest States Smart Work Zone Deployment Initiative and the Federal Highway Administration, the research aims to determine how specific PCMS messages influence driver behavior and to identify best practices for temporary traffic control. The study was motivated by the need to improve work zone safety and efficiency, as well as to fill a gap in the literature regarding the detailed evaluation of sequentially placed PCMS with text and number-based messages. The researchers employed a mixed-methods approach, combining a driving simulator experiment with a survey of State Departments of Transportation (SDOTs). The simulator study replicated a 6.2-mile section of Interstate 44 in rural Missouri, featuring a lane closure and four sequentially placed PCMS. Fifty-two participants, balanced by gender and spanning ages 18 to 62, drove through five scenarios: a control scenario with no messages and four experimental scenarios, each displaying a different message sign (MS-1 through MS-4). These messages ranged from general warnings ("Caution Work Zone Ahead") to specific instructions ("Speed Ahead 30 mph") and urgent alerts ("Prepare to stop; Stopped traffic ahead"). Vehicle speeds were recorded at 0.1-second intervals and analyzed using Analysis of Variance (ANOVA) to assess changes in mean and 85th percentile speeds before and after each sign. Additionally, participants completed post-driving surveys to subjectively rate message effectiveness. The results demonstrated that PCMS significantly reduced driver speeds compared to the control scenario, where the mean speed was 62.55 mph on a 70 mph highway. MS-4 ("Prepare to stop; Stopped traffic ahead") produced the largest objective speed reduction, decreasing mean speed by 48.91 mph. MS-3 and MS-2 resulted in reductions of 39.46 mph and 36.06 mph, respectively, while MS-1 reduced speed by 9.35 mph. Statistically significant speed differences were primarily observed in the interval immediately preceding the lane closure. However, subjective evaluations revealed that MS-2 ("Speed Ahead 30 mph; 2 min to end of WZ") was rated as the most effective message by drivers. Participants preferred MS-2 because it provided specific, actionable speed information, and the 85th percentile speeds in this scenario closely matched the displayed advisory speed. The study concludes that while PCMS are effective tools for reducing speeds in work zones, the specific content of the message significantly impacts driver compliance and perception. Messages providing specific speed advisories are perceived as more useful and easier to follow than general warnings or urgent stop alerts, despite the latter causing greater absolute speed reductions. The findings suggest that transportation agencies should prioritize specific, informative messaging to enhance driver compliance. The authors recommend further research to evaluate PCMS effectiveness under varying traffic conditions, weather, and times of day, as well as to determine optimal placement and message sequencing.

Key finding

The message sign warning drivers to prepare for stopped traffic ahead resulted in the highest speed reduction of 48.91 mph compared to the control scenario, while drivers subjectively rated the sign specifying a 30 mph speed limit as the most effective.

Methodology

simulator

Sample size: 52

Provenance

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Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.

Topics

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• work zones
• speed choice
• perceptual countermeasures
• speed management
• signage environment

Information type

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• Applied Guidance: countermeasure evaluation
• Empirical Findings: behavioral performance data