The Effect of Roadside Vegetation and Clear Zone Design on Driver Behavior

Roadside vegetation provides a myriad of environmental and psychological benefits to drivers. Research has shown that, although natural landscapes cause less stress and frustration to the driver, the same vegetation may increase the severity of run-off-the-road crashes. This study evaluates the relationship between clear zone design and the presence of roadside vegetation on driver speed, lateral positioning, and drivers’ visual scan patterns. A driving simulator was utilized to test six combinations of clear zone sizes and roadside vegetation densities. Participants’ driving performance was measured throughout the virtual drive. While there were no statistically significant differences between drivers’ speeds, the speed trends that were found correlate to statistically significant observations in previous research, further validating the effect of clear zone size on driver speed. Along left curves, drivers drove closer to the centerline when there were trees near the edge of the road. Based upon the recorded drivers’ eye movements, the horizontal scan pattern did not significantly change between combinations, suggesting that drivers use their peripheral vision to monitor potential hazards.

  • Record URL:
  • Supplemental Notes:
    • This research was sponsored by the U.S. Department of Transportation, University Transportation Centers Program.
  • Corporate Authors:

    University of Massachusetts, Amherst

    Department of Civil and Environmental Engineering
    130 Natural Resources Road
    Amherst, MA  United States  01003

    Safety Research Using Simulation University Transportation Center (SaferSim)

    University of Iowa
    Iowa City, IA  United States  52242

    Office of the Assistant Secretary for Research and Technology

    University Transportation Centers Program
    Department of Transportation
    Washington, DC  United States  20590
  • Authors:
    • Knodler Jr, Michael A
    • Fitzpatrick, Cole D
  • Publication Date: 2016-1


  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Figures; Photos; References; Tables;
  • Pagination: 21p

Subject/Index Terms

Filing Info

  • Accession Number: 01610808
  • Record Type: Publication
  • Files: UTC, TRIS, USDOT
  • Created Date: Aug 29 2016 9:40AM