Performance Evaluation of 29-inch and 31-inch W-beam Guardrails on Six-lane, 46-foot Median Divided Freeways

This report summarizes the research efforts of using finite element modeling and simulations to evaluate the performance of single-faced and double-faced North Carolina Department of Transportation (NCDOT) W-beam guardrails for different heights under Manual for Assessing Safety Hardware (MASH) Test Level 3 (TL-3) impact conditions. A literature review is included on performance evaluation of W-beam guardrails as well as applications of finite element modeling and simulations in roadside safety research. The modeling and simulation work was conducted on fourteen single-faced and double-faced NCDOT W-beam guardrails (with placement heights of 29 and 31 inches) placed along a six-lane 46-foot median divided highway with 2.5H:1V and 4H:1V slopes. The single-faced guardrails were also evaluated with a horizontal median curvature of three degrees and the double-faced guardrails were also modeled and evaluated with a lower backside rail. The guardrails with 29- and 31- inch placement heights were impacted by a 1996 Dodge Neon and a 2006 Ford F250 at 62 mph (100 km/hour) and an impact angle of 25°. Two additional Dodge Neon simulations, one at each guardrail height (i.e., 29 and 31 inches), evaluated the single-faced guardrail without horizontal curvature with an impact speed of 70 mph (112.6 km/hour). The guardrails performance was determined by evaluating the vehicular responses based on MASH exit-box criterion, MASH evaluation criterion F, exit angles, yaw, pitch, and roll angles, transverse displacements, and transverse velocities. The simulation results demonstrated the effectiveness of the 29- and 31-inch single-faced and double-faced guardrails placed on a median divided freeway under MASH TL-3 impact conditions. Under small angle vehicular impacts (i.e., 25°), the guardrails with 29- and 31-inch placement heights were shown to be effective at retaining the impact vehicle but exhibited a high likelihood for tire snagging and vehicle spin-out. Finite element modeling and simulations were shown to be both effective and efficient and can be used to study crash scenarios that are difficult and/or extremely expensive to conduct with physical crash testing.


  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Figures; Photos; References; Tables;
  • Pagination: 141p

Subject/Index Terms

Filing Info

  • Accession Number: 01603523
  • Record Type: Publication
  • Report/Paper Numbers: FHWA/NC/2014-14
  • Created Date: May 31 2016 9:23AM