Guardrail is a type of longitudinal barrier installed along a roadside to shield vehicles from hazards. Guardrail itself is a hazard and should be installed only if it would reduce the severity of accidents. Accordingly, the American Association of State Highway and Transportation Officials (AASHTO) has guidelines that can be used to evaluate the need for guardrail. The Virginia Department of Transportation (VDOT) has, for the most part, adopted these guidelines for its interstate, primary, and arterial road systems. However, these guidelines are generally based on information concerning high-speed, high-volume roads, and VDOT bases decisions regarding the need for guardrail on its secondary road system entirely on engineering judgment. Guidelines are needed to assist in evaluating the need for guardrail on secondary roads, which most typically have low-volume and low-speed traffic. The purpose of the research was to develop such guidelines. The original scope of the study was to develop guidelines from existing practices as reported in the literature and from a survey of other states. It was concluded, however, that VDOT needed guidelines based on Virginia-specific data. Accordingly, the scope of the study was expanded to include a cost-effective analysis. Based on the application of the computer program ROADSIDE, guidelines to determine if guardrail is needed on fill embankments and for fixed objects were developed for use with secondary roads in Virginia. The former guidelines were defined in terms of volumes and fill heights for a given slope, whereas the latter guidelines were defined in terms of a required clear zone for a given volume.

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 45 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00605738
  • Record Type: Publication
  • Report/Paper Numbers: VTRC 91-R15
  • Created Date: Mar 31 1991 12:00AM