Reducing work zone crashes by using vehicle’s flashers as a warning sign : final report

Bai, Yong; Li, Yingfeng · 2009 · ROSA P / Kansas. Dept. of Transportation

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Summary

This study addresses the critical safety issue of crashes in one-lane, two-way work zones on rural two-lane highways, which constitute a significant portion of Kansas’s highway system. The research was motivated by high rates of severe crashes, particularly rear-end collisions caused by inattentive driving, in these specific work zone configurations. To mitigate these risks, the Kansas Department of Transportation (KDOT) sponsored an evaluation of the Emergency Flasher Traffic Control Device (EFTCD). This low-cost, flexible warning system requires drivers entering a work zone where stopping is necessary to activate their emergency warning flashers, thereby alerting following vehicles to the stopping condition. The researchers conducted field experiments in three one-lane, two-way work zones in Kansas: two with a 55-mph speed limit and one with a 65-mph speed limit. The experimental design involved collecting vehicle speed data using SmartSensor HD devices under two conditions: with and without the EFTCD implementation. Additionally, researchers administered surveys to drivers to assess their interpretation of the warning sign and gather recommendations for its potential adoption. Statistical analyses, including two-sample t-tests and Chi-square tests, were employed to compare mean speeds and the proportion of high-speed vehicles between the two conditions. The results demonstrated that the EFTCD effectively reduced mean vehicle speeds within the work zones and decreased the proportion of vehicles traveling at notably high speeds. Statistical tests confirmed significant differences in speed distributions between the control and experimental groups. Furthermore, driver survey data indicated that the EFTCD successfully captured the attention of the majority of approaching drivers. Most surveyed drivers recommended the implementation of this warning sign, citing its effectiveness in alerting them to the work zone conditions. The study concludes that the EFTCD is an effective traffic control measure for one-lane, two-way work zones, offering a cost-effective and flexible solution particularly beneficial for work zones that are frequently relocated during construction. The findings suggest that utilizing vehicle flashers as a warning sign can enhance safety by reducing speeding and improving driver awareness. The implications of this research extend beyond Kansas, offering a viable safety strategy for other states with extensive rural two-lane highway systems. The report also provides recommendations for future research to further validate and refine the implementation of this device.

Key finding

The Emergency Flasher Traffic Control Device effectively reduced mean vehicle speeds and the proportion of notably high speeds in one-lane, two-way work zones while successfully capturing driver attention.

Methodology

field_study

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

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• emergency work zone conspicuity
• work zones
• perceptual countermeasures
• roadway lighting effects
• rail grade crossings

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