Flagger Operations: Investigating their Effectiveness in Capturing Driver Attention

Principal Investigator(s):

Kathleen Harder, Former Senior Research Associate, College of Design


  • John Hourdos, Former Research Associate Professor, Civil, Environmental and Geo-Engineering

Project summary:

Work zone-related crashes are a nation-wide concern. This past year, the state of Minnesota recorded 1,700 work zone-related crashes. One of the key work zone issues involves flagger operations and flagger safety. Previous studies show that the known presence of human workers directly affects driving speed in work zones. However, driver inattention to the presence of human workers (including flaggers) is a primary safety concern. With the increase of work zone-related crashes, it is important to ensure that there is a warning system that effectively captures and sustains driver attention and fosters compliance to minimize work zone fatalities. This two-pronged (driving simulation and field study) investigation of driver behavior in work zones contributes basic and applied knowledge to the understanding of work zone safety. In the driving simulator study, a fully interactive PC-based STISIM driving simulator was used to test the effectiveness of roadway elements designed to capture and sustain the attention of drivers in flagger-operated work zones. The participants were 160 licensed drivers from four age groups: 18-24, 32-47, 55-65, and 70+ years of age. Each participant drove each of the three conditions in counterbalanced order. The driving simulator study revealed that the new set of elements is more effective than the elements currently used to reduce driving speeds on the approach to a flagger-controlled work zone. No difference in mean driver speed was found in response to the sign with an LED presence. The dynamic speed display coupled with the horn is more effective than the dynamic speed display alone. The cognitively engaging elements identified as effective in the driving simulator study were tested in two field operational tests. The field tests revealed that all but one of the elements identified in the experimental driving simulator study were effective. In particular, the findings revealed that a combination of the speed trailer and horn barrel are effective in reducing the overall speed of vehicles approaching the field study work zone. The field test revealed that the new experimental layout practically eliminated high-speed outliers in addition to its success in reducing driver approach speed to the flag operator.

Project details:

  • Project number: 2014002
  • Start date: 05/2013
  • Project status: Completed
  • Research area: Transportation Safety and Traffic Flow
  • Topics: Safety