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Mid-America Transportation Center

NDOR Maximum Safe Guardrail Height



  • Principal Investigator: Dean Sicking ( (402)472-9332)
  • Project Status
    In Progress
  • Start Date: 7/1/2011
  • End Date: 12/31/2012
  • About this Project
    W-beam guardrails are by far the most common restraint system used along both local and major roadways. Traditionally, these restraint systems have been fullscale crash tested with a rail height ranging between 27" and 32". However, the maximum rail height which can guarantee a safe performance of guardrails, especially in impacts involving small vehicles, has never been identified. The main concern associated with an increase of the rail height is that small vehicles, because of their low profile, may have a tendency to lift the rail and penetrate the barrier. The objective of this project will be determining the critical rail height at which small vehicles start under-riding the barrier. A potential increase of the rail location could provide several benefits in terms of both an improved safety of the system with vehicles characterized by a high center of mass and economic advantages related to the maintenance of the roadside This study will use computer simulations to investigate the safety of the Midwest Guardrail System (MGS) with the rail located higher than 32 in. from the ground level, considering various impact angles and grading scenarios ranging from flat terrain to minor slopes. Also, potential problems with a small 820-kg vehicle and the influence of a different frontal geometry for a standard 1100-kg MASH vehicle will be considered. Finally, simulation results will be used to determine guidelines for installation, maintenance and retrofitting of guardrails.
    Total Project Cost
    $ 45,207